Talk:Mercury (planet)/Archive 1

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Input From Younger Wikipedians

This page has a lot of useful infomation for a 13 year old girl like me and i am doing reasearch on Mercury and I got most of my project done on this website or that page. Thanks again amanda 13 from albany NY

No problem, Amanda. This is the whole reason why we're working on Wikipedia in the first place, and comments like this let us know that it's all worthwhile. :) Bryan
  • Amanda's comment prompted me to come out and become an user. Twelve-year-old Dralwik 01:53, 11 Nov 2004 (UTC)
Yes, soon the school industry will be left in shambles! BWAHAHAHAHAH! Susan Mason
It will with all the pupils using websites like this! --06cat 08:43, 6 February 2007 (UTC)
I think this has helped me with my Solar System research 0_o; Thanks for, erm, existing, Wikipedia! <3

~ Paratroopa Platoon #174

Why is this page so confussing? I mean I am doing a science project and I dont understand this website at all. Well anyways buh-bii!!<> ~ Megan LeBlanc 4-27-07

I use Wikipedia for most of my research, and when I need more, I can look at the external links. I'm 13 btw. 05:39, 25 August 2006 (UTC)

3rd Theory?

Pizza, you added "A third theory argues that the outer parts of Mercury were "eroded" by the solar wind." as one of the explanations that have been presented for why Mercury has such a big core. How is this different from the theory mentioned immediately before it, in which Mercury's crust was vaporized and blown away by solar wind? Did it blow Mercury's crust away while it was still solid instead, in which case, how were such hellaciously strong solar winds possible? I think this could use more detail, or some kind of reference, or something. Bryan 02:15 8 Jul 2003 (UTC)

Yes, the third theory is similar to the second -- except, the argument is not so much that the heat of the solar nebula vaporized the crust and it was then blown away; but rather, that the impact of particles upon the mantle (rather than the crust - which was not solid, but also not vaporized) stripped the outer layers. The two theories vary as to the timescale; the second one involves a longer more gradual process. Pizza Puzzle

Oh, and also, I just removed this paragraph:

Unlike Earth, Mercury does not have synchronous rotation around Sol. In addition, gravitational force have created tidal bulges upon the planetary surface.

because Earth doesn't have synchronous rotation, and all planets have tidal bulges so I don't see what's special about Mercury's. Bryan

Well this text here states: "The Sun created a significant tidal bulge on Mercury...", I suppose it was wrong to infer that Earth had a synchronous rotation. Pizza Puzzle

Temperature Variation

According to the table in Earth its temperature varies from 184K to 333K. The way I reckon that makes 149K between them, not 11K. Maybe its just a misunderstanding on my part as to what that 11K refers to; but it probably could be expressed more clearly.

I suspect that this is just the average temperature variation between day and night at any given point, not the global extremes. Bryan
Bryan is correct. Pizza Puzzle

Gravity Corrections

OK, anonymous editor comes along and adds in the surface gravity compared to Earth, which is nice. But also "corrected" the straightforward surface gravity from 2.78 m/s² to 0.926 m/s². Fits with the compared-to-Earth number of 0.0945, at least. But meanwhile, using the numbers in there for the mass and diameter, I get a surface gravity of 3.70 m/s². Looking back through the history, it's been 2.78 m/s² since the page first got a surface gravity. What gives?!? -- John Owens (talk) 23:25, Mar 26, 2004 (UTC)

Checking his/her other edits, some of them look OK, some of them don't. Phobos (moon) seems not right, but Deimos (moon) looks good, Iapetus (moon), Uranus (planet), and Venus (planet) seem OK. Will add more here as I check them out. -- John Owens (talk) 23:39, Mar 26, 2004 (UTC)
All the other edits from that IP (User: | contributions) look OK. It's just Mercury here and Phobos that aren't right, but I don't know if I can even agree with the prior 2.78 m/s² figure here. -- John Owens (talk) 00:00, Mar 27, 2004 (UTC)
Every reference I can find lists the surface gravity of Mercury as 38% of Earth's. Which would make it 3.71 ms-2. -- DrBob 00:12, 27 Mar 2004 (UTC)
OK, I went ahead and made the changes here and at Phobos. Though I'm a bit conflicted about Phobos, since it depends on where you measure its diameter, but the numbers that were there weren't even between the max and min diameter gravities. I used the min diameter, max gravity there. -- John Owens (talk) 00:35, Mar 28, 2004 (UTC)

Supernova survival

What is this?

Furthermore, in the (unlikely) event of a nearby star going supernova, the large iron core of Mercury could protect the colonists in almost half of the possible directions; if this happened, the colonists at Mercury's pole might well be the only human survivors in our Solar System.

Does anyone have a source for this, or is it speculation? --Doradus 20:25, Nov 11, 2004 (UTC)

Sounds like speculation. A supernova would need to be really near to us to produce enough radiation that a planetary core is necessary for shielding it, and I don't think any candidate stars are that close. Furthermore, the initial pulse of strong radiation would not last very long so even fast-rotating planets like Earth would have significant portions of its surface shielded just as well. I don't think it's a problem. I found this page with some information about radiation levels from nearby supernovae: [1] Bryan 07:03, 12 Nov 2004 (UTC)
Ok, I chopped it. For posterity, the version with the supernova speculation is here.

Human colonisation

Why does the Mercury article talk about Human colonisation when the other planetary articles do not?

Probably because the colonisation of Mercury provides interesting chalanges unique in our solar system. Armaced 15:57, 6 Apr 2005 (UTC)
Also because Mercury plays a pivotal role in some alternate interstellar propulsion schemes --such as those where high-power lasers are used to push solar sails. Basing those on Mercury makes some sense.
Urhixidur 2005 July 2 16:25 (UTC)

Would it be possible to cite a source or external reference for the information about the potential for human colonization which is included in this article (something like a NASA study, a paper in a scientific journal, or a web site)? --DannyZ 05:45, 22 May 2005 (UTC)

Ephemeris of Mercury

Why not to put an ephemeris for mercury in the Wikipedia? The following ephemeris runs from January 1st, 2005 to January 1st, 2015. Right ascension and declination are in actual equinox. First column is right ascension, second declination, third elongation to sun. The ephemeris is valid for 0h UTC

A prime reason why not is that this list of data is huge. It's ~160 kilobytes of raw numbers of very little interest to the average reader of this sort of article. Perhaps someplace like Wikibooks or Wikisource might be more appropriate? Bryan 04:26, 20 Jun 2005 (UTC)
I just deleted the list entirely, it was wasting a huge amount of space in this talk page. It's available in the article's history still. Bryan 2 July 2005 19:16 (UTC)

Mercurian Day?

On the Potential For Human Colonization subject it was written that a base on Mercury could use a heat sink to store up heat for the night. Does the author realize a mercurian day is about 60 days long? Or was the section talking about Earth's Moon still? If it was, it should be made clearer. (PS. I'm kinda new to wikipedia, correct me if I'm doing something wrong here)

From the article-

"Due to the lack of atmosphere to conduct heat, a thermal radiator hidden in the shadow of a sun screen would be able to reject heat into space even at the height of the Mercurian day. Alternatively, the base could use a heat sink during the day to store up heat for disposal during the night. Protecting mobile vehicles or robots against solar heating might prove much more difficult, however, which may limit the amount of surface activity that could be performed during the day."

(Personally, I'd make a mobile base that would just crawl along the surface at about 4 mph to stay in the nice twilight.) [unsigned]

Mercury's got no atmosphere so the base would only have to deal with radiant heat from above and conducted heat coming through the rock below. Radiant heat can be largely dealt with using reflective sunshades and conduction through rock isn't particularly fast, so there might actually not be a huge amount of extra heat to deal with - a large heat sink might be quite adequate even during a 60 day long day. I haven't run any numbers, though, I'm just suggesting that it may not be as outlandish as it seems. A base under similar conditions with an atmosphere would get more severely cooked because the atmosphere would circulate past it, enhancing heat transfer.
Oh, and you're doing nothing wrong - this is exactly the sort of thing these talk pages are for. :) Bryan 2 July 2005 19:24 (UTC)
Thanks for responding,

I do wonder if a heat sink would be able to dissipate enough heat away in an near perfect vacuum. I've heard the shuttle will overheat if the bay doors don't open in orbit. By the way, have you seen Mercury recently? Yesterday was the first time I've seen it. It's just above the horizon just after it gets dark. The special treat is Venus, which is only 1 degree away. But you may already have heard about that. And by the way, lets not try to land on Venus any time soon- sulfuric acid rain, 400 degrees in the shade, etc. [unsigned]

Page move

I disagree with the page move to just Mercury instead of Mercury (planet). There was no discussion here on the talk page, and (more importantly) Mercury is unique among planets in that the word "mercury" has another meaning that is arguably just as common: that of the chemical element. (Well, not really unique I guess: "earth" can mean dirt, and "Pluto" might be a cartoon dog.) --Doradus 01:16, August 14, 2005 (UTC)

I agree completely - the move should not have been done at all. I'll take a look and reverse the move if need be. -- Chuq 01:53, 14 August 2005 (UTC)
The pages have been moved back. I just noticed the user who made the change (User:Kitch) has done the same to Pluto, Saturn and Neptune.. I may leave these for someone else to look at! -- Chuq 09:42, 14 August 2005 (UTC)

Cut sections

I've just re-written quite a lot of the article for style and accuracy. I've removed two sections, on the potential for space colonisation and data about elongations; the first, because it seems to be pure speculation, and the second because it is an enormous block of table which seems out of place in an encyclopaedia article. Others might disagree with my removal; for convenience I've copied them both here:

Potential for human colonization

A crater at the North or South pole of Mercury might prove to be one of the best locations for an off-Earth colony, as the temperature would remain almost constant (at around minus 200 degrees Celsius). This is because Mercury has negligible axial tilt and essentially no atmosphere to carry heat from its sunlit portion. It would thus always be dark at the bottom of a crater at the planet's pole, even a shallow one. Human activities could warm the colony to a comfortable temperature, and the low ambient temperature would make waste heat disposal easier than most locations off Earth.

A base elsewhere would have to be able to deal with many weeks of continuous intense solar heating followed by many weeks without any external heating at all. This would not necessarily be as difficult as it may first seem. Facilities could be buried under several meters of loose-packed regolith, which in a vacuum would serve as effective thermal insulation as well as a radiation shield. Similar approaches have been proposed for bases on Earth's Moon, which has two-week-long days followed by two-week-long nights. Due to the lack of atmosphere to conduct heat, a thermal radiator hidden in the shadow of a sun screen would be able to reject heat into space even at the height of the Mercurian day. Alternatively, the base could use a heat sink during the day to store up heat for disposal during the night. Protecting mobile vehicles or robots against solar heating might prove much more difficult, however, which may limit the amount of surface activity that could be performed during the day.


Greatest Eastern Elongation Stationary, retrograde Lower Conjunction Stationary, prograde Greatest Western Elongation Upper Conjunction
November 21, 2004 22.2° November 30, 2004 December 10, 2004 December 20, 2004 December 29, 2004 22.5° February 14, 2005
March 12, 2005 18.3° March 19, 2005 March 29, 2005 April 11, 2005 April 26, 2005 27.2° June 3, 2005
July 9, 2005 26.2° July 22, 2005 August 5, 2005 August 15, 2005 August 23, 2005 18.4° September 18, 2005
November 3, 2005 23.5° November 14, 2005 November 24, 2005 December 4, 2005 December 12, 2005 21.1° January 26, 2006
February 24, 2006 18.1° March 2, 2006 March 12, 2006 March 24, 2006 April 8, 2006 27.8° May 18, 2006
June 20, 2006 24.9° July 4, 2006 July 18, 2006 July 28, 2006 August 7, 2006 19.2° May 18, 2006
October 17, 2006 24.8° October 28, 2006 November 11, 2006 November 17, 2006 November 25, 2006 19.9° January 7, 2007
February 7, 2007 18.2° February 13, 2007 February 23, 2007 March 7, 2007 March 22, 2007 27.7° May 3, 2007
June 2, 2007 23.4° June 15, 2007 June 28, 2007 July 10, 2007 July 20, 2007 20.3° August 15, 2007
September 29, 2007 26° October 12, 2007 October 23, 2007 November 1, 2007 November 8, 2007 19° December 17, 2007
January 22, 2008 18.6° January 28, 2008 February 6, 2008 February 18, 2008 March 3, 2008 27.1° April 16, 2008
May 14, 2008 21.8° May 26, 2008 June 7, 2008 June 19, 2008 July 1, 2008 21.8° July 29, 2008
September 11, 2008 26.9° September 24, 2008 October 6, 2008 October 15, 2008 October 22, 2008 18.3° November 25, 2008
January 4, 2009 19.3° January 11, 2009 January 20, 2009 February 1, 2009 February 13, 2009 26.1° March 31, 2009
April 26, 2009 20.4° May 7, 2009 May 18, 2009 May 30, 2009 June 13, 2009 23.5° July 14, 2009
August 24, 2009 27.4° September 6, 2009 September 20, 2009 September 28, 2009 October 6, 2009 17.9° November 5, 2009
December 18, 2009 20.3° December 26, 2009 January 4, 2010 January 15, 2010 January 27, 2010 24.8° March 14, 2010
April 8, 2010 19.3° April 18, 2010 April 28, 2010 May 11, 2010 May 26, 2010 25.1° June 28, 2010
August 7, 2010 24.2° August 20, 2010 September 3, 2010 September 12, 2010 September 19, 2010 18.2° October 17, 2010
December 1, 2010 21.2° December 10, 2010 December 20, 2010 December 30, 2010 January 9, 2011 23.3° February 25, 2011
March 23, 2011 18.6° March 30, 2011 April 9, 2011 April 22, 2011 May 7, 2011 26.6° June 12, 2011
July 20, 2011 26.8° August 2, 2011 August 17, 2011 August 26, 2011 September 3, 2011 18.1° September 28, 2011
November 14, 2011 22.7° November 24, 2011 December 4, 2011 December 14, 2011 December 23, 2011 21.8° February 7, 2012
March 5, 2012 18.2° March 11, 2012 March 21, 2012 April 3, 2012 April 18, 2012 27.5° May 27, 2012
July 1, 2012 25.7° July 14, 2012 July 28, 2012 August 7, 2012 August 16, 2012 18.7° September 10, 2012
October 26, 2012 24.1° November 7, 2012 November 17, 2012 November 26, 2012 December 4, 2012 20.6° January 18, 2013
February 16, 2013 18.1° February 22, 2013 March 4, 2013 March 16, 2013 March 31, 2013 27.8° May 11, 2013
June 12, 2013 24.3° June 25, 2013 July 9, 2013 July 20, 2013 July 30, 2013 19.6° August 24, 2013
October 9, 2013 25.3° October 21, 2013 November 1, 2013 November 10, 2013 November 18, 2013 19.5° December 29, 2013
January 31, 2014 18.4° February 6, 2014 February 15, 2014 February 27, 2014 March 14, 2014 27.6° April 26, 2014
May 25, 2014 22.7° June 7, 2014 June 19, 2014 July 1, 2014 July 12, 2014 20.9° August 8, 2014
September 21, 2014 26.4° October 4, 2014 October 16, 2014 October 25, 2014 November 1, 2014 18.7° December 8, 2014
January 14, 2015 18.9° January 21, 2015 January 30, 2015 February 11, 2015 February 24, 2015 26.8° April 10, 2015
May 7, 2015 21.2° May 19, 2015 May 30, 2015 June 11, 2015 June 24, 2015 22.5° July 23, 2015
September 4, 2015 27.1° September 17, 2015 September 30, 2015 October 8, 2015 October 16, 2015 18.1° November 17, 2015
December 29, 2015 19.7° January 5, 2016 January 14, 2016 January 25, 2016 February 7, 2016 25.6° March 23, 2016
April 18, 2016 19.9° April 29, 2016 May 9, 2016 May 21, 2016 June 5, 2016 24.2° July 7, 2016
August 16, 2016 27.4° August 30, 2016 September 12, 2016 September 21, 2016 September 28, 2016 17.9° October 27, 2016
December 11, 2016 20.8° December 19, 2016 December 28, 2016 January 8, 2017 January 19, 2017 24.1° March 7, 2017
April 1, 2017 19° April 10, 2017 April 20, 2017 May 2, 2017 May 17, 2017 25.8° June 21, 2017
July 30, 2017 27.2° August 12, 2017 August 26, 2017 September 4, 2017 September 12, 2017 17.9° October 8, 2017
November 24, 2017 22° December 3, 2017 December 13, 2017 December 23, 2017 January 1, 2018 22.7° February 17, 2018
March 15, 2018 18.4° March 22, 2018 April 1, 2018 April 14, 2018 April 29, 2018 27° June 6, 2018
July 12, 2018 26.4° July 25, 2018 August 9, 2018 August 18, 2018 August 26, 2018 18.3° September 21, 2018
November 6, 2018 23.3° November 17, 2018 November 27, 2018 December 6, 2018 December 15, 2018 21.3° January 30, 2019
February 27, 2019 18.1° March 5, 2019 March 15, 2019 March 27, 2019 April 11, 2019 27.7° May 21, 2019
June 23, 2019 25.1° July 7, 2019 July 21, 2019 July 31, 2019 August 9, 2019 19.1° September 4, 2019
October 20, 2019 24.6° October 31, 2019 November 11, 2019 November 20, 2019 November 28, 2019 20.1° January 10, 2020
February 10, 2020 18.2° February 16, 2020 February 26, 2020 March 9, 2020 March 24, 2020 27.8° May 4, 2020
June 4, 2020 23.6° June 17, 2020 July 1, 2020 July 12, 2020 July 22, 2020 20.1° August 17, 2020
October 1, 2020 25.8° October 14, 2020 October 25, 2020 November 3, 2020 November 10, 2020 19.1° December 20, 2020
Worldtraveller 23:13, 5 September 2005 (UTC)


Why does the table give: Declination 61.45° I thought that declination of planets is variable. Cartes du Ciel says that mercury's declination is now +03°41'04.1? [unsigned]

I'm also confused about that. I guess the north pole of mercury points to that position. 19:23, 17 March 2007 (UTC)
Yes, that's what it was. The infobox has been fixed to reflect this better now. Urhixidur 04:08, 19 March 2007 (UTC)

Exploration of Mercury

"The approaching spacecraft cannot use aerobraking to help enter orbit around Mercury since it has no atmosphere and must rely on rocket boosters." MESSENGER "will explore the planet's atmosphere, composition and structure." How can it explore the planet's atmosphere if it has none? Teply 04:26, 29 November 2005 (UTC)

If you look at the infobox (at the top right of the article) you will see that the atmosphere is listed as "trace" - that is, there is an atmosphere of sorts (most likely, I guess, outgassing from the baked sunwards side, and the odd stray atom floating around on the dark side) but it is very tenuous and certainly not sufficient to give any appreciable friction for aerobraking. In fact, it is so rarified that the atoms in it may be so far apart that they never collide (see exosphere). [2]
It is not too different to the Moon [3]. But the atmosphere that is present, such that it is, is worth exploring. -- ALoan (Talk) 12:22, 29 November 2005 (UTC)

Proposed move

The following discussion is an archived debate of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

The result of the debate was: consensus was to not movejiy (talk) 19:05, 8 January 2006 (UTC)

  • Oppose. The dis-ambiguation page has 2 primary meanings, the planet and the element. Georgia guy 02:19, 2 December 2005 (UTC)
  • Oppose. The element is at least as important as the planet, and even the god might be a reason to keep a disambig page at Mercury. Kusma (talk) 02:56, 2 December 2005 (UTC)
  • Oppose. Google search for mercury returns the automobile company! :-) Seriously, I don't see the strong case for the planet over any other meaning. Tedernst | Talk 04:16, 2 December 2005 (UTC)
  • OPPOSE, Hg is by far the more prevalent meaning. 23:40, 2 December 2005 (UTC)
  • Oppose. Hg is more frequently linked and the god is also primary. Jonathunder 03:12, 3 December 2005 (UTC)
  • Oppose. The planet and the element are neck-and-neck. Urhixidur 04:54, 3 December 2005 (UTC)
  • Oppose. As per above. Marco79 17:19, 3 December 2005 (UTC)
  • Oppose, for the reasons explained above.--Jyril 18:07, 3 December 2005 (UTC)
The above discussion is preserved as an archive of the debate. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

Wrong duration of bombardment

In the section Surface Features the following is said:" was heavily bombarded by comets and asteroids for a period of about 8000 million years." AFIK, our solar system is only about 4500 million years old. Shouldn't it rather say 800 million years or something like that? Bye. CalRis


"Mercury (planet)" applies the phrases "Morning Star " and "Evening Star" to Mercury. The separate articles "Morning Star" and the like refer to Venus. 15:01, 1 February 2006 (UTC)


I've just been looking at the German version of this article, and I think the way theirs is laid out is better than this is at the moment. It allows coverage of all significant aspects of the planet in a very clear and organised way. Below is their TOC - what would anyone think about rearranging our article along these lines? Worldtraveller 00:48, 11 March 2006 (UTC)

1. Structure

1.1 Atmosphere
1.2 Surface
1.2.1 Possibility of ice Indications in the detail Possible origin
1.3 Internal structure: core, mantle and crust
1.3.1 Cause of high iron content
1.4 Magnetosphaere
1.5 Geological development stages

2 Orbit and rotation

2.1 Advance of perihelion
2.2 Orbital resonance

3 Research

3.1 Ground-based research
3.2 Research with space probes
3.2.1 Marine 10
3.2.3 BepiColombo

4 Observation

4.1 Visibility

5 Cultural history
6 See also
7 Literature
8 Web links

8.1 Video

I took this TOC and put all of our current content into it - see Mercury (planet)/temp. It highlighted some gaps in our coverage which I've started to fill. If no-one objects I'll move what's in the temp page to this page later today. Worldtraveller 11:55, 23 April 2006 (UTC)

I implemented the new structure in the main article. I have to say I think it is much clearer than the previous. It's highlighted some gaps though! Worldtraveller 09:13, 25 April 2006 (UTC)

Chthonian planet?

"Tentative suggestions have been made that Mercury may be a Chthonian planet." Can anyone provide any citation for this? It is also mentioned on the chthonian planet page, no citation there either. Chaos syndrome 17:47, 19 March 2006 (UTC)

I couldn't find any backing for this claim so I removed it when I changed the structure. Worldtraveller 09:13, 25 April 2006 (UTC)


The section edit boxes all appear at Orbit. Could someone fix that? I don't know how to fix formatting things of that sort, as far as I know those are automatic and I don't have experience dealing with such things. --Keflavich 05:06, 24 April 2006 (UTC)

I don't know if there's anything we can do about that unfortunately. The edit links are placed automatically by MediaWiki and only removing the info box would get them back to the right place, I think. Worldtraveller 09:13, 25 April 2006 (UTC)


The section on cultural understanding is one that needs work. Can anyone add to it? Once it's a decent overview I'm thinking this article is beginning to look like it might be a worthy FA candidate. I'm just adding references and tidying up prose in the rest of the article at the moment. Worldtraveller 10:04, 26 April 2006 (UTC)

I moved this section to a better place and renamed it 'Early astronomers'. The Singing Badger 12:36, 26 April 2006 (UTC)
OK, I like that. Bit of a gap between the greeks and the 17th century though - I'll see what I can find out and if anyone else can add anything that would be great. Worldtraveller 12:51, 26 April 2006 (UTC)

Spelling consistency

I'm editing the article to make all spellings consistently follow American usage. This is because the oldest version of the article used American spellings (kilometer, not kilometre). Angr (talkcontribs) 09:08, 29 April 2006 (UTC)

What colour is Mercury?

The NASA maps of the planet make the surface look brown. Yet I've seen artist's impressions that make the planet grey, like the Moon. Does anyone know which is correct? The Singing Badger 02:11, 2 May 2006 (UTC)

Mercury's Magnitude

The maximum magnitude of Mercury seems to be -1.9. A standard magnitude seems to be -0.42. The average magnitude seems to be 0.0. The minimum is about 1.3 or a slightly higher number. The numbers in the article seem to be wrong.

According to Astronomy magazine, Mercury will have an apparent magnitude of -0.9 on June 9, which is half a magnitude brighter than the maximum of -0.42 listed here. That -1.9 seems reasonable, but the -.42 is clearly wrong--Syd Henderson 21:13, 14 May 2006 (UTC).

This page gives the range as roughly -2.0 to 5.5. I've changed the numbers in the article, and investigated the history - the numbers were added in July 2003 and haven't been questioned until now! Thanks for picking up on this long-standing error! Worldtraveller 23:26, 18 May 2006 (UTC)
Here are some others: My Peterson Guide Stars and Planets (2000 Edition) says -2.3 is the maximum magnitude of Mercury, but Kaufman's Universe (1985) and The Guiness Book of Astronomy Facts and Feats (2nd Edition, 1983) both agree on -1.9. The "About -2" is okay.)--Syd Henderson 03:03, 19 May 2006 (UTC)

Distance from the Sun

Shouldn/t Mercury's distance from the Sun appear near the top of the article? I imagine this # is buried in some astro. shorthand in that table, but it should be more plain, no? Sfahey 03:05, 25 May 2006 (UTC)

Advance of perihelion

The explanation given sounds like it is referring to phenomena predicted by special relativity, not general relativity. That is incorrect, as the SR contribution is only about 7"/century, and was already taken into account before Einstein published his explanation based on GR. I don't know an easy way to explain how the anomalous precession derives from GR, or I'd fix this myself. --Mmm 08:21, 16 July 2006 (UTC)

The GR contribution as given in "The Fundamentals of General Relativity" published in 1916 by Einstein can be derived form an effective potential

where l is the mass specific angular momentum, c the speed of light, and r the distance to the center of mass. The calculation is purely classical, neglecting any chance in mass. The potential is effective in the sense that the trajectory is calculated as if there would be a potential of that size. But, it depends on the angular momentum, a property of the planet rather than the gravitational field of the Sun.

Moreover, the effective potential causes other chances to the trajectory rather than only an advance of the perihelion.

A pure advance of the perihelion would be decribed as

where p,e and k are constants and the angle between the space componentents in cartesian coordinates. Such a trajectory would result from a potential of the form 09:15, 23 March 2007 (UTC)

I believe the SR contribution is indeed about 15"/century. This is the result of the following simulation.

#include <stdio.h>
#include <math.h>


 int N = 1500000,i;        /* number of iteration steps, counter for time */
 double AE = 1.49598E11;   /* AU average distance Earth to Sun  */
 double c  = 299792458;    /* speed of light                    */
 double e  = 0.0256;       /* eccentricity of orbit             */
 double a  = 0.3871;       /* semi majajor axis                 */
 double pi = 4*atan(1);    /* 3.1415 ..                         */
 double wfak = (180/pi)*3600;  /* convertion to arc seconds     */
 double rx = a*(1-e)*AE;       /* distance mercury sun          */   
 double ry = 0;
 double T = 87.969*(60*60*24); /* siderial period */
 double vx = 0;
 double vy = AE*(2*pi*a)*(1+e)/T;  /* max. orbital speed  */
 double GM=1.32712440018E20;  /* G mass of Sun             */
 double mcc = 1;              /* rest energy               */
 double v;
 double E,m,px,py,p;          /* energy, mass, momentum,  */
 double beta,flag=1;          
 double w0,w1;                /* initial and final position of perihelion  */
 double dt = T/(double)N;     /* interation step - time interval           */
 double r0,r;                 /* distance to sun                           */
 int max = 100*N;
 int count = 0;               /* number of perihelion transits */
  v = sqrt(vx*vx+vy*vy);
  beta = v/c;
  E = mcc/sqrt(1-beta*beta);
  r = sqrt(rx*rx+ry*ry);
  m = E/(c*c);
  py = m * v;
  px = 0;
    rx += vx*dt;
    ry += vy*dt;

    r = sqrt( rx*rx + ry*ry );
    if (r < r0 && i>1) {
        if (flag==1) printf("aphelion %d %f %f\n",i,r,wfak*ry/rx);
    if (r > r0 && i>1) {
        if (flag==-1) {
            printf("perihelion %d %f %f\n",i,r,wfak*ry/rx);
            if (count==0) w0 = wfak*ry/rx;
            w1 = wfak*ry/rx;
    r0 = r;
    /* dp = F * dt */
    px -= ((m*GM)/(r*r*r))*rx * dt;
    py -= ((m*GM)/(r*r*r))*ry * dt;
    p = sqrt(px*px+py*py);
    /* E^2 = (m0 c^2)^2 + (pc)^2 */
    E = sqrt(mcc*mcc + (p*c)*(p*c));
    /* E = m c*c */ 
    m = E/(c*c);
    /* v = p/m */
    vx = px/m;
    vy = py/m;
 printf("\n\nSR contribution /century %f\n",


This result looks quite plausible, since the relative mass dilation

is even somewhat smaller than the advance of perihelion measured in radians.

It looks unrealistic to measure such small pertubations. At least there are many speculation about all kind of pertubations of the orbit in that order of magnitude, which are not completely understood. 08:12, 29 March 2007 (UTC)

But this consideration seems to be wrong, since the mass is m = E/c2 = (Ekin + Epot)/c2. The total energy of Mercury is (almost) constant, so that there is (almost) no effect. -- 11:50, 31 August 2007 (UTC)
The question is, wether Epot contributes to the mass of Mercury, the Sun or the Solar System. Epot is neglectable compared to the rest energy of the Sun, so that in this case the simulation might be correct. -- 09:38, 2 September 2007 (UTC)

Smallest planet?

Now that Pluto's not a planet anymore, Mercury is probably the smallest planet. Discuss.PhoenixSeraph 14:02, 24 August 2006 (UTC)

Not much to discuss. Article's 1st sentence has been changed appropriately.--Planetary 00:25, 25 August 2006 (UTC)
I completely disagree that there is nothing to discuss. "Planet" is part of the English language and not a trademark of the Internation Astronomical Union; regardless of their vote, many people will continue to consider Pluto a planet, myself among them. It is POV to declare Mercury the smallest planet. Nareek 02:00, 25 August 2006 (UTC)
So the NPOV thing to do is make sure the article points out who holds which views. I'll add some further clarification. Bryan 03:04, 25 August 2006 (UTC)
Was it POV to declare Pluto the smallest planet? By your definition of "point of view," yes, because you could just consider whatever you wanted to be a planet. Simply because enough people agree that something is true does not make it true, sir. Go read Nineteen Eighty Four, or if you already have, this time pay attention. Also, the comments about this alternative point of view are innappropriate for this article given that the issue is about Pluto and the planetary redfinition, not Mercuy. Such discussions belong in those articles. Mikeguy 03:13, 25 August 2006 (UTC)
I'm not sure I follow your objection, but it seems to me that discussion of whether Mercury is the smallest planet in the solar system is entirely relevant in the article that's about Mercury. I'm also not saying that it's necessarily "true" that Mercury is the smallest planet. I do, however, say that it's true that it is currently considered by the IAU to be the smallest planet in accordance with their recent change in what they consider to be a planet. Whether you agree with them or not, this is a factual description of their POV. Bryan 03:24, 25 August 2006 (UTC)
The 1984 analogy is hardly apt, unless you believe that a group of mathematicians could get together and declare that 2 and 2 equals 5. Whether Pluto is a planet or not is a matter or semantics, not a matter of reality, just as is the question of whether Europe is a continent or not. If a substantial number of people continue to believe that Pluto is a planet, and I believe they do, Wikipedia should reflect this disagreement.
The relevance of this controversy to the question of whether Mercury is the smallest planet or not shouldn't need to be pointed out. Though I'm satisfied with the current attribution of Mercury's size status to the IAU; the representation of dissenting views should be at the Pluto article. Nareek 03:32, 25 August 2006 (UTC)
Mikeguy: these comments are rather foolish. Obviously Pluto's status impacts on comparitive statements in other articles, so discussion cannot be confined to the Pluto article. Furthermore, you cannot simply invoke 1984 as evidence that what people generally think is irrelevant! Pluto *is* regarded as a planet by the general public - if you were reading the opening sentence of this article, then it would be easy to assume pluto was bigger than Mercury. (Craig M) —Preceding unsigned comment added by (talk) 13:06, 14 January 2008 (UTC)

I have restored the introductory sentence to say that Mercury is the "innermost and smallest planet" so that this article can be internally Wiki-consistent with the Pluto article and the Solar System template which both recognize Pluto as a dwarf planet and thus inherently support the notion that Mercury is the smallest planet in the solar system. I have, however, moved the dispute to a footnote where visitors may see that Mercury's status as the smallest planet is dependent on the recent IAU redefinition and that this is disputed by some unsourced group of people. Actual references to reputable disputes of the reclassification (something more than a blog entry) would be welcome and perhaps aid the Wiki-community in coming to a consensus as to how the dispute should be dealt with. However, I wish to make clear that from my perspective it is unacceptable to hedge Mercury's status as the smallest planet simply because of personal attachment to Pluto without adequate sourcing as to a reputable dispute concerning Pluto's status, particularly given the fact that elsewhere Wikipedia clearly supports the IAU redefinition as definitive. Bojangles04 16:22, 25 August 2006 (UTC)

I completely endorse the current first sentence and footnote. Couldn't have said it better myself. —Keenan Pepper 17:42, 25 August 2006 (UTC)

For sake of neutrality, I don't support adding the word "smallest" to the lead, especially to today's featured article. The lead should only contain information that is completely undisputed, and I believe it can do without a size ranking. So "Mercury is the innermost planet..." would be sufficient as the first sentence.
By the way, I generally support IAU's redefinition. However, we should put firm astronomical facts first and try not to fill the article with terminological and linguistical arguments. 20:15, 25 August 2006 (UTC)

Profanity Removal

There is destructive "graffiti" at the end of the first paragraph. I tried to edit it out but it does not appear on the editing page. Anyone know how we can get this removed? [unsigned]

Visibility Times

The statement "its greatest angular separation from the Sun (greatest elongation) is only 28.3° (it can only be seen in twilight)." came as a big surprise to me. Can any one please explain why Mercury cannot be seen at dawn as well, half a Mercurian year (44 days) later?

Thanks, --AVM 17:28, 25 August 2006 (UTC)

Twilight happens before dawn as well as after sunset. This seems to be the source of your confusion. Twilight just means that the sun is below the horizon but the sky is still light. —The preceding unsigned comment was added by (talk) 23:09, 23 December 2006 (UTC).

Irony? Coincidence? Taunting?

I find it amusing that Mercury is the featured article on the Main Page the very same day that Pluto is on the Main Page "In the news" for its "demotion" from planet. Agent 86 22:10, 25 August 2006 (UTC)

Probably a coincidence, I think the chances are just too large...--Planetary 22:20, 25 August 2006 (UTC)
See Apophenia Raul654 23:57, 25 August 2006 (UTC)


The article states that Mercury's gravity is too small for it to hold any substatial atmosphere. Yet Titan's atmosphere is thicker than earths, despite having much less gravity than either Earth or Mars. So how can this be the reason Mercury has such a small atmoshere? 23:23, 25 August 2006 (UTC)

The sun blows away any gasses on mercury's surface. Raul654 23:56, 25 August 2006 (UTC)
It's not 'the Sun', it's the Solar wind. --AVM 03:29, 26 August 2006 (UTC)
And where does it originate? Picky picky ;) Raul654 03:15, 27 August 2006 (UTC)
Mercury does have an atmosphere, it's just so thin, it's not enough to affect the planet in any way. This atmosphere mostly results from the solar wind hitting the surface and interacting with the atoms of the rock. As for Titan's atmosphere, well, it's a bit of a mystery. That's why the Cassini spacecraft's observations of Titan arehighly important.--Planetary 05:01, 27 August 2006 (UTC)
The solar wind is much weaker at Titan's distance from the sun... It also spends almost all of its time inside Saturn's Magnetosphere which deflects solar wind aswell, stopping particles from ionizing n "blowing away" -- Nbound 23:04, 6 September 2006 (UTC)
According to some books and also German Wikipedia, the main chemical element in Mercury atmosphere is oxygen. --Wizzard 21:35, 9 October 2006 (UTC)

Recent Vandalism

I found this added to the end of the first paragraph from "Mercury does not have any moons, but is a tiny bit bigger than our moon." GravityIsForSuckers 03:15, 30 August 2006 (UTC)

That's nice, but next time just delete it and don't mention it here. Vandals want attention.--Planetary 07:07, 30 August 2006 (UTC)
Acknowledged. GravityIsForSuckers 14:29, 30 August 2006 (UTC)

Smallest planet

I know we're all excited about Pluto no longer being a planet, but honestly the "smallest planet in the solar system" in the first sentence is going to be misleading to a lot of people. I had added the clarification "smallest of the 8 planets in the solar system" but I see that's been removed. Footnotes are also well and good, but the average person isn't going to read them. I strongly suggest being a bit more explicit about where it stands, at least until Pluto is no longer considered a planet by the average man on the street - probably a few more years at least. Stevage 10:03, 30 August 2006 (UTC)

Agreed -- Nbound 10:20, 30 August 2006 (UTC)

Atmosphere composition

Comparing the article to a page on NASA, im gettin different values... Are we using old figures here... or is NASA...

-- Nbound 01:24, 7 September 2006 (UTC)

Comparing sources... both seem to be from the same publisher, same year with different authors...

Current Source: Potassium 31.7% Sodium 24.9% Atomic Oxygen 9.5% Argon 7.0% Helium 5.9% Molecular Oxygen 5.6% Nitrogen 5.2% Carbon dioxide 3.6% Water 3.4% Hydrogen 3.2%

Other Source: Atmospheric composition: 42% Oxygen (O2), 29% Sodium (Na), 22% Hydrogen (H2), 6% Helium (He), 0.5% Potassium (K), possible trace amounts of Argon (Ar), Carbon Dioxide (CO2), Water (H2O), Nitrogen (N2), Xenon (Xe), Krypton (Kr), Neon (Ne)

there seems to be a significant difference :| -- Nbound 01:28, 7 September 2006 (UTC)


The argument for the advance of Mercury's perihelion does not appear to view the orbit of Mercury from the perspective of the focus of its orbit, which is the centre of the sun. If this were applied and taken to its logical conclusion, by starting from the basis of the average velocity/mass and applying mass dilation in the hemisphere of the aphelion, a lower than average mass would result and thus a reduced velocity at the aphelion and an undershooting of its predicted position. And as the time Mercury spends in the hemisphere of the aphelion is far greater than that in the opposite, the result would be to more than cancel out the suggested perihelion advance, which in turn would have the overall effect of reversing the observed precession. I would be interested in an explanation. Romun 07:35, 11 September 2006 (UTC)

Requested move

Please discuss at Talk:Mercury --GW_SimulationsUser Page | Talk 20:58, 12 September 2006 (UTC)

Observation section

Within the section titled "Observation", several things appear to be wrong:

  • There is no apparent retrograd motion which lasts "8 to 15 days on either side of inferior conjunction"
  • The maximal apparent elongations are not synchronized with Earth's rotation so the paragraph explaining a difference between northern and southern hemisphere makes no sense
  • The phase of maximal apparent magnitude should vary between gibbous and crescent (because it depends on where Mercury is on its elliptic orbit and again this is not synchronized with Earth's orbit)

Icek 04:06, 17 November 2006 (UTC)

Mercury's Double Sunrise

I think that this article should have a picture of the double sunrise, if possible. A better version of this graphic, [[4]] Thanks, CarpD (^_^)


There is a discussion at Wikipedia_talk:WikiProject_Astronomical_objects#Planet_infobox_conventions_.28km_vs._AU_vs._miles.29 on standardizing the planet infoboxes, as well as the possibility of changing the planet diameter to radius. If you care about these things, let your opinion be heard there. Lunokhod 10:08, 4 December 2006 (UTC)


Vandalism spotted, but I am not able to edit, since the vandalism is not visible in edit mode. Salimi 19:08, 7 December 2006 (UTC)

If it's not visible when you go to edit it, that usually means that someone has already corrected it. Try reloading the page. siafu 19:13, 7 December 2006 (UTC)

Mercury heat

Mercury's heat may go up to 800 degree f, on the other side of the planet it may lower to 200 f below zero. It would take 85 Earth days to get around the sun.

Mercury has no moons, it does have volcanos. Mercury has more than 500 volcanos —The preceding unsigned comment was added by (talk) 23:11, 15 January 2007 (UTC). Dominic Tarro Delray Beach Fl, (289-2969)

What just happened up there???-- Planetary (talkcontribs) 05:21, 16 January 2007 (UTC).

Core size

Hey everybody,

one one find an estimation for a core size with 65% of the whole planet size and NOT as written in the article 42%. My guess is 65% by mass = 42% by volume; both numbers being subject to assumtions which have credibility, but are unproven. Neil And what is meant by planet size, part of the volume or part of the total mass in Mercury's mass distribution? (Maybe this makes the different between Messanger-site and wikipedia?) Can someone comment on it? (Sorry for my poor English, I am just a German guy.) —The preceding unsigned comment was added by (talk) 14:04, 3 February 2007 (UTC).

semi-minor-axis and orbital circumference

With the values of aphelion distance and perihelion distance from this article, I calculate the semi-minor-axis to = 56 671 637,01 km (believe me - i used my (by me) developed equation : b = sqr ( ((aph + per) / 2)² + ((aph - per) / 2)²) , but i dont want to explain the equation - its hard to write for me in English - test and compare it with every other accepted equation (for this planet, and if you want, for any other planet and object) - you will see : I'm right). With the same equation you can calculate the semi-minor-axis for article of planets, which only give the semi-MAJOR-axis. For the orbital circumference i have calculated with numerical integration the very exact value of : 359 976 796,63 km - test and compare it with the exact values of the semi-major-axis and semi-minor-axis, on this link : or any other exact equation for the circumference of an ellipse will see, I'm right. I can't make the changes in this article, because I'm only signed up at the german wikipedia. But if nobody make this mathematically correct changes in this article maybe I sign up here, and make the changes for all planets, who gives the aphelion and perihelion distances, but only the semi-major-axis, and not the semi-minor-axis - and just a not-exactly orbital circumference, like in the Mercury-article. Lots of Greets from Austria, Pygmalion1 (24. February 2007 , 12:03 (CET))

The orbit of Mercury is not exactly an ellipse (it precesses, mostly), so the orbital circumference is not that of an ellipse and is actually very hard to specify. A difference in orbital circumference of .008% is not significant. The orbital circumference is only given to two places for this reason. Michaelbusch 18:12, 24 February 2007 (UTC)
If small differences are not important, why the exact values for aphelion distance, perihelion distance, etc. It could round it to the next 100 km's - not so important ;-) - only few 10^-4 % ... You know, what i mean ? I know : Mercury not closing the ellipse, but he has a "period" from which "he" start a knew "cyclus" and for this point, it can calculate a value for this "circumference". The value of 360 million kilometres is not "more right", when the track of mercury not an ellipse ;-) Or: for example, in this case i would write "approximately 360 Million kilometres" in the article, for orbital circumference. But the other exactly given values for the track, suggest's that the orbital circumference also exact - and that can't be in this case. Like i say : if it stand "appr. 360 Million" its ok - but not, if one value of track is given exactly, another value just "circa", and something like this - seems a little bit unprofessionell - maybe just for me. Greetings, Pygmalion1 (24. february 2007 (21:56 CET)) —The preceding unsigned comment was added by (talk) 20:54, 24 February 2007 (UTC).
The orbital elements given in the article are osculating elements: at a particular reference time specified in the J2000 coordinates, they define an ellipse tangent to Mercury's position and velocity. That ellipse is defined to as accurately as we know the position of Mercury, which is at the sub-km level, and determines Mercury's trajectory given the positions, velocities, and masses of the other masses in the solar system, but Mercury is not on that ellipse. The orbital circumference could refer to the circumference of that ellipse (which you calculated), the distance Mercury travels in heliocentric coordinates between one perihelion and the next, the distance Mercury travels between passing a particular angle in the heliocentric frame and next passing that angle (i.e. when it has gone around the Sun), or the distance Mercury travels in a time equal to the period derived from the osculating elements. Because of this multitude of different definitions, giving orbital circumference to many places is non-sensical. I have added an 'approximate' mark to the infobox. Michaelbusch 21:44, 24 February 2007 (UTC)
You're right - but every planet has these specifications, - so the 'approximate'-mark would make sense at every planet (for the orbital circumference) ? I think so. Meanwhile the other thing : the semi-minor-axis is not important, when there was given a semi-major-axis ? I know: it suggests an ellipse for mercury - but that also does with the semi-major-axis, dont you think so ? If there is a semi-major-axis given, i think its good to give a semi-minor-axis too - like the articles for few other planets (they have the semi-minor-axis - a few ;-)). The 'approximate-mark' pleased me - thanks ;-) - and thanks for the explainings. Greetings, Pygmalion1 (and sorry again, for my weak english) (25. February, 10:30 (CET)) —The preceding unsigned comment was added by (talk) 09:30, 25 February 2007 (UTC).
a semi-major axis is practically always given, a semi-minor hardly ever. The mathematical properties of the semi are very special, and it is constantly used in astronomical calculations. The semi-major is usually what people mean when they talk about "average" of "mean" distance. I agree with your earlier comment; we can round off a few more places. Saros136 09:56, 25 February 2007 (UTC)
Pygmalion1, there are other problems here, too.

First, b can be calculated using only the semi-major axis a and eccentricity e. I got a number only about 450 meters different than yours, ending with a .453 I used an infinite series formula for the circumference (which uses a and e), getting 359976739.60 km. I calculated it with Excel. (Then decided to check against an even higher-precision calculator-right on the money) The problem here is that the given numbers aren't precise enough to calculate to the nearest km. Lower e and higher a gives greater circumference, changing the numbers (adding or subtracting .5 and .000000005) gives a range of 6.6 km.

Actually, the actual perihelion varies by hundreds of km. Saros136 11:15, 25 February 2007 (UTC)

Thanks for your fast answer, and your work with the values of distances and orbital circumference. You handle the values good - but there are great differences between the formulas for ellipse's. Espescially, when the e-value is so high, like the mercury-e > 0.2 . I used two formulas - in the first : the one with the numeric integration (link in my first posting to this thread), and in the other the last equation for U at : (at the bottom, with the number 6). These two formulas give the same (!) value for the orbital circumference. For the second equation i used my calculator with 13 digits precision (which could take the whole formula in one row). The second formula give a precision (error) for the orbital circumference, that is under 1 * 10^-9 . Thats less than 100 meters, for the mercury orbital circumference , so i trust these equations. But i know : there are many equations for the circumference of ellipses, which has a greater error (ignores the precission of the a, e, etc. - if the formula is not presice enough- the precise values dont matters). But thanks again for the verification of my calculations. Greetings, Pygmalion1 (26. February 2007 , 20:03 (CET)) —The preceding unsigned comment was added by (talk) 19:03, 26 February 2007 (UTC).

Orbital Resonance Animation

After one orbit, Mercury has rotated 1.5 times, so after two complete orbits the same hemisphere is again illuminated.

I threw together an animated version of the orbital resonance graphic, I think it may help illustrate the idea a little better, at least to the layman, but I wanted to see what you all think first. --Age234 21:06, 11 March 2007 (UTC)

...And it's not showing up. It's there when you click on the broken image. Weird. --Age234 21:08, 11 March 2007 (UTC)
Very nice! I've seen Wikipedia occasionally choke on thumbnails like this, perhaps it's having trouble reducing an animated gif? You could try uploading a manually shrunken version in addition to the full-sized one. Also, I'd suggest putting the image on Wikimedia Commons instead, that way every language of Wikipedia can use it. Bryan Derksen 00:32, 15 March 2007 (UTC)
It would be a bit more "natural", imho, to have the arrow point to the sun at alternate perihelia rather than at alternate aphelia. —Tamfang 23:09, 30 April 2007 (UTC)

Magnetic field strengh?

I believe the strength of Mercury's magnetic field quoted (1% of Earth's) is in error. I have two astronomy textbooks ("Astronomy: The Solar System and Beyond" and "World's Apart") in front of me that say it is "about 10^-4 of earth's" and "about 1/3000th of earth's", respectively. 13:09, 14 March 2007 (UTC)

I've changed it to "about 0.1%", since that's well within an order of magnitude of 1/3000th. What edition is your copy of "Astronomy"? I put in a citation for the 4th edition (2004) edition since that's what Amazon handed me when I searched, and I expect the figure is unlikely to have changed much in other editions, but it's still good to ensure the citation is as accurate as possible. Bryan Derksen 00:25, 15 March 2007 (UTC)

Mercury the planet versus the element

Maybe if Wikipedia allows lowercase titles in the future, this article can be at Mercury while the article on element would be at mercury. Voortle 23:08, 29 March 2007 (UTC)

Surface feature?

In the main pic for this article, there is something that appears to be a prominant surface feature. It's the thing that looks like an arm with a Pac-Man puppet reaching down from the top of the planet. I couldn't find mention of that particular feature in the article, so I'm wondering if the "feature" is just an area of the planet that wasn't scanned by whatever probe or telescope took the picture. If somebody has that info, please include it in the article so I and others like me will be less confused! JSC ltd 15:34, 11 April 2007 (UTC)

At the image's description page Image:Reprocessed Mariner 10 image of Mercury.jpg it says "The smooth band is an area of which no images were taken", is that the feature you're referring to? I like your description of what it looks like. :) Bryan Derksen 18:00, 11 April 2007 (UTC)
Ah, yes. I should have remembered the old axiom, "when all else fails, read the image description!" Thanks for clearing this up for me. JSC ltd 15:35, 16 April 2007 (UTC)

Molten fluid interior

On Yahoo just minutes ago, apparently...[5] Didn't put it in the article because it was made featured-status by likely-superior writers, who'd know better how to incorporate it. --Chr.K. 13:05, 4 May 2007 (UTC)

Cornell article [6] Apparently there are other elements in the core with lower melting points. Brian Pearson 01:21, 6 May 2007 (UTC)

References for Sidebar

The Sidebar has only one reference, for one item, to detail where the information came from. Could someone actually support these data? This is also applicable to the other planets. --MatthewKarlsen


I've checked and the IPA pronunciation is ˈmɜrkyəri. May i know why it is an ɹi behind? Thanks. —Sengkang 04:20, 18 July 2007 (UTC)


"Despite its slow 176-day-long rotation..." Is this right? Elsewhere it says 58 days. Richard75 23:21, 21 July 2007 (UTC)

The 176-day figure is for Mercury's "day" (noon to noon), whereas the planet rotates every 58 days. In the context of the magnetosphere, I would guess that the planetary rotation is the significant detail. Thoughts? --Ckatzchatspy 23:30, 21 July 2007 (UTC)

atmosphere composition

The article gives a variety of atmospheric constituents but is unreferenced. Here at NSSDC they give values which are very different. I would be inclined to believe NASA rather than the unreferenced values given in this article, at least that data is traceable. However, does anyone have a reference for the values that are currently in the article? Deuar 13:47, 3 August 2007 (UTC)

Very good Article Status (red link problem)

I am an editor on Simple English Wikipedia, and I have researched the facts about the "Very Good Article" status. In Simple English Wikipedia, "Very Good Articles" are not meant to have a single red link, yet I see that this article has one red link in the category: Advance of perihelion. Also, in the same category, there is a link that makes no sense. Either you fix these, or delete them. otherwise, this page may be likely to lose its very good article status. 11:07, 28 October 2007 (UTC)

The Future of Mercury

I have added a section called "The Future of Mercury". I was not sure what section to put this in or if people even want this included in the article. I do think some of this is worth mentioning somewhere in the article. I mentioned, "Current theories suggest that in 7.7 billion years, when the Sun has exhausted its central supply of hydrogen and has become a red giant, that the Sun will engulf Mercury." References: NewScientist and The Once and Future Sun
-- Kheider 20:56, 29 October 2007 (UTC)

The Sun won't burn for another 7.7 Gyr. 5 Gyr is a better number. Michaelbusch 21:20, 29 October 2007 (UTC)

Space in the Eccentricity value

There's an space splitting the value of Mercury's eccentricity (0.205 30294). I guess it misses a "6" in that place but I'm not an expert. Regards. —Preceding unsigned comment added by (talk) 01:05, 29 December 2007 (UTC)


I added information about Mercury as a former moon of Venus as the last paragraph of Internal Structure which it probably is but this is rarely mentioned. There is also the question of it being the smallest planet; I consider it to be the smallest MAJOR planet. See my website for a definition of planet and major planet. Great article by the way, deserving of FA assessment. Star Guy. —Preceding unsigned comment added by Bpell (talkcontribs) 08:28, 3 January 2008 (UTC)

A well made contribution, though perhaps it would be better placed in another subsection; such as Orbit and rotation? Nigholith (talk) 08:36, 3 January 2008 (UTC)


First images in: see: Encounter Observation Phases

Not sure about the copyright status of this image; it's made of MASA images, but it was assembled by Emily Lakdawalla of the Planetary Society

Serendipodous 22:22, 14 January 2008 (UTC)

Formatting Problem with "Polar Ice Cap" Section

Hey guys, I've looked at this on two different browsers, and both times, when I look at the "Radar Image of Polar Ice Cap" photo, it's positioned in such a way that it's cutting off text in the paragraph about the Geological makeup of Mercury. I'm just learning about formatting, so I'm not sure how to do it, but maybe someone else can fix it? Editortothemasses (talk) 12:15, 15 January 2008 (UTC)

This is now a Spoken Article

I've added a reading of this article. MasterDirk 05:11, 16 January 2008 (UTC)

Intro out of date / add arrival of MESSENGER.

I changed the intro to indicate that Mariner was "the first of two satellites to approach Mercury...", now that MESSENGER has arrived at Mercury. Hopefully this isn't considered controversial... TMSTKSBK (talk) 14:30, 16 January 2008 (UTC)

Main Photo

I like that the Messenger image is now the main photo for the page, as it's cool to have a hi-res picture when one wasn't previously available. I liked the old photo, though, for one reason - the color. I think a black and white photo detracts from the "atmosphere" of the article - Mercury, in my mind, has always had a reddish tint to it. I liked the Mariner photo that was up before, and is now found lower on the page. I have a colorized version of the Messenger photo that I matched (more or less) to the color on the Mariner photograph which I think might look good (or anyone else could make one, I don't really care) - the only problem is copyright info. On NASA's site, the Messenger photo is credited variously to Nasa, Johns Hopkins, and at least one or two other research institutes. I don't know what that means for a derivative (colorized) verision, if such a thing would even be possible. Anybody have any thoughts/input about the subject? —Preceding unsigned comment added by (talk) 18:16, 16 January 2008 (UTC)

Do not revert the main photo!

Mariner 10 no longer represents the best source or most recent of information regarding Mercury. --Starks (talk) 16:35, 17 January 2008 (UTC)

What colour is Mercury? Brown or grey?

Stupid question, but the article does not (so far as I can see) answer it. The maps of Mercury make it look brown, and I've seen images (like this NASA artist's impression) depicting it that way. Yet I remember reading somewhere that Mercury is in fact grey, and the maps were not intended to represent its true colour. Am I right about this? Rubble pile (talk) 17:43, 17 January 2008 (UTC)

At this point, I do not believe any color pictures have been taken of Mercury up-close. The Mariner pictures looked brown because of the imaging processed used at the time; the photos returned by MESSENGER are black and white because of the imagine processing used today. Color images of planets typically involve taking several "black and white" images using filters which block everything but a very narrow band of the spectrum. Being "black and white", they can be transmitted across large distances with a high degree of redundancy which decreases noise and keeps the picture sharp. The separate images are then colored based on the spectrum used and then combined, creating the "almost true" images you may have seen of Jupiter and Saturn. This approach also allows for colors to be exaggerated, which helps bring out details of fine shading that might otherwise be obliterated.
It will take a few days, even weeks, before the composits can be processed and made public. Until then, just sit back and gasp in amazement. TechBear (talk) 17:50, 17 January 2008 (UTC)
Thanks, I do realize that, but I was just wondering if it was true about the brown being inaccurate. Believe me, I'm gaping! :O Rubble pile (talk) 18:02, 17 January 2008 (UTC)

it's brown i think this should be the front image —Preceding unsigned comment added by SquallLeonhart ITA (talkcontribs) 19:05, 22 January 2008 (UTC)

Again that's not a true-color image "and the colors seen in the accompanying image are somewhat different from what a human would see." -Ravedave (talk) 20:17, 22 January 2008 (UTC)

How heavy is 'heavily cratered'?

The article mentions "heavily cratered" - can someone add to the surface geology section a statement discussing whether Mercury is more heavily cratered than, say, the Moon? And explain why? I envision asteroids smashing into Mercury at higher velocity than they'd smash into anything else because they've been pulled by the Sun more strongly and for longer than an asteroid smashing into anything else in the solar system. Tempshill (talk) 05:32, 18 January 2008 (UTC)

Finally a true color image

now this should definitely be the front image, it's very good quality and TRUE color [and almost total perspective) —Preceding unsigned comment added by SquallLeonhart ITA (talkcontribs) 00:28, 31 January 2008 (UTC)

It's a nice image, but it's still false color, despite the headline. It incorporates an infrared component, to accentuate color differences - see the description. -- Avenue (talk) 01:08, 31 January 2008 (UTC)
Still better than B&W. I uploaded the image, then cropped it and re-uploaded. Does it look distorted to anyone else? The image itself is fine; it just gets distorted when embedded. kwami (talk) 01:56, 31 January 2008 (UTC)
I know everyone's excited about color images, but this one looks both fuzzy and distorted. I'd prefer clarity over color. I also don't think false color photos should be the front image. X3210 (talk) 02:31, 31 January 2008 (UTC)

Crust and Mantle

Crust = 100-200 km Mantle = 600 km Core = 1800 km Total = 2500-2600 km But Mercury's radius is only 2440 km!

I have read elsewhere that the 600 km refers to the lithosphere, which consists of the crust + the mantle.
Eroica (talk) 14:06, 31 January 2008 (UTC)

Blue Stuff?

What's this blue stuff the Messanger probe found? Shouldn't we all go nuts about it? I'll sign later. —Preceding unsigned comment added by (talk) 11:53, 31 October 2008 (UTC)


I reworded the intro somewhat, hopefully for the better, and added two fact tags: I've always seen the symbol for Mercury described as Hermes' caduceus, not the caduceus plus head and hat, and the Sumerian name looks like it might have lumped phonograms and determinatives together. sd/- sumit kwami (talk) 06:47, 2 February 2008 (UTC)

We are all children of the sun, we all came out of the sun so why do we fight? We all came from one source. —Preceding unsigned comment added by (talk) 21:46, 8 October 2008 (UTC)


What is up with all the attacks today? Have the vandals decid to target this page? Or some school asked about a paper on mercury and they are venting their frustrations. Should we request a semi-prot? Samuel Sol (talk) 19:11, 29 February 2008 (UTC)

What do you mean today? 3 days ago there were 8 attacks. But I'll protect it if you like. kwami (talk) 19:20, 29 February 2008 (UTC)
I reverted the page at least once today. Other editors reverted more (I remember two at least). It looks calmer now, so it may not be necessary. But I will keep an eye if it continues. Samuel Sol (talk) 19:41, 29 February 2008 (UTC)

Other Language Names

Basing myself on this comment during Neptune's FAC. I'm removing from the main article the foreign names of the planet. And copying it below.

The Greeks of Hesiod's time called it Stilbon ("the gleaming") and Hermaon.
In India, the planet was named Budha (बुध), after the son of Chandra (the Moon). The Chinese and Sinoxenic cultures know the planet as the "water star" (水星), after one of the Five Elements. The Hebrews named it Kokhav Hamah (כוכב חמה), "star of the hot one" ("the hot one" being the Sun).
Our name for the planet comes from the Romans, who named it after the Roman god Mercury, which they equated with the Greek Hermes and the Babylonian Nabu.

Samuel Sol (talk) 17:07, 4 March 2008 (UTC)

I left the part on the body, although I'm not sure it belongs in the article. More comments about ancient observations would be awarented(sp?). Samuel Sol (talk) 17:21, 4 March 2008 (UTC)
I'll see if I can find anything useful... Kaldari (talk) 17:35, 4 March 2008 (UTC)
Still on the name, I'm not sure about using Planets as source. Is it reliable? Samuel Sol (talk) 19:17, 4 March 2008 (UTC)
Yeah, strangely that was the best source I could find on the Sumerian names of all the planets. I'll see if I can find something better. Kaldari (talk) 19:34, 4 March 2008 (UTC)

(<-) Nice new source mate. Just to be sure, book? Journal? To update to the the cite template. Samuel Sol (talk) 20:11, 4 March 2008 (UTC)

Beat you to it :) That one took some digging, BTW, but apparently it is the definitive source. Kaldari (talk) 20:15, 4 March 2008 (UTC)
Sweet. Well done mate. Damn work and most of the internet blocked :P Samuel Sol (talk) 20:20, 4 March 2008 (UTC)

A note for future editors: Some sources (including the NASA source) precede the Sumerian transcription with "MUL". "MUL" was a symbol used by the Sumerians to designate that they were referring to a star or planet, but it is not considered part of the actual name. Some sources superscript it like so: MULUDU.IDIM.GU4.UD. Also, the "4" is a reference number in the Sumero-Akkadian Transliteration system to designate which of several syllables a certain Sumerian sign is most likely designating. Some sources list the Sumerian name as simply "Udu-idum-gu-ud", which is basically correct. The version I have used in the article is exactly how it is printed in the original Hunger and Pingree article (which is considered the definitive source on the matter). Kaldari (talk) 20:31, 4 March 2008 (UTC)

Also, while Hunger and Pingree translate the name as "the jumping planet", a strictly literal translation would be more like "wild sheep, bull/steer of the sun". Although since there are apparently a million different ways to translate Sumerian, I think "the jumping planet" is as good as it gets. Kaldari (talk) 20:37, 4 March 2008 (UTC)
I added a shorter version of the note above to the article notes, since I think it might be useful to people actually researching the historical names. Kaldari (talk) 21:31, 4 March 2008 (UTC)
Thanks, Kaldari. That answers my concern about someone mixing up determinatives with phonograms. By the way, the Chinese name was correct, at least for Chinese, Japanese, and Korean. — kwami (talk) 09:25, 8 March 2008 (UTC)
Oh, and in Japanese, Wednesday is literally 'water day' - an apparent loan translation. — kwami (talk) 09:30, 8 March 2008 (UTC)


It seems that every hour this article pops up on my watch list with s.o. reverting vandalism. It's FA - shouldn't it have some minimal protection? — kwami (talk) 18:14, 6 March 2008 (UTC)

Earliest records of Mercury

Our article currently says that Mercury has been known since the 3rd millennium BC, but we don't provide any reference for this statement. The MUL.APIN record referenced in the citation I added only dates back to about 1370 B.C. Anyone know of earlier records than that? Kaldari (talk) 23:28, 11 March 2008 (UTC)

After doing some more digging, I'm afraid our entire section on Sumerian and Babylonian records of Mercury may be wrong. The earliest record of Mercury I can track down is from the MUL.APIN, which dates to c. 1400 BCE. By that time, the Sumerians were long gone and the Babylonians were running things. According to our article, the MUL.APIN it is a record of "Babylonian astrology", not Sumerian. The MUL.APIN tablets are written in the Sumerian language, however, which may be the source of the confusion. Unfortunately, I don't know enough about the history of the Sumerians and Babylonians to feel comfortable rewriting the paragraph. Also, I don't know if this is the actual first record of Mercury or not. Sources on this issue seem to be virtually non-existant. Can anyone offer some assistance in sorting this out? Kaldari (talk) 21:00, 11 April 2008 (UTC)
I tried cleaning up the wording of this section a bit. Someone needs to add info on the Mayas knowledge of Mercury as well. Kaldari (talk) 20:50, 7 May 2008 (UTC)

Still FA?

Parts of this article look like they would not survive a FAC. There are long stretches of facts with no citations to back them up and the citations are not properly formatted. I'm also seeing a few stub paragraphs. This may need an FAR soon.—RJH (talk) 21:39, 28 March 2008 (UTC)

I agree. This article has undergone a lot of revision since it was promoted to FA two years ago, especially due to the recent MESSENGER fly-by. It could use some clean-up and additional citations. I've tried to clean-up the Magnetic field and (sup) Ancient astronomers sections, but there are still areas that need more help. The first four paragraphs of the Orbit and rotation section for example, have no citations at all. Kaldari (talk) 18:43, 2 April 2008 (UTC)
Thanks.—RJH (talk) 21:47, 9 April 2008 (UTC)

The mean temperature is listed as 452 K; but the Mercury fact sheet lists 440 K. I'm not sure where the 452 came from and that makes the other temperature values dubious.—RJH (talk) 21:47, 9 April 2008 (UTC)

If this article is demoted, who do you anticipate will do the work required to return it to FA status? —Preceding unsigned comment added by (talk) 23:44, 6 May 2008 (UTC)
There are several dedicated individuals in Wikipedia:WikiProject Astronomical objects and Wikipedia:WikiProject Solar System who have performed much work bringing the Solar System articles up to FA. (See Wikipedia:Featured topics/Solar System.) But once a page reaches FA, I think it still needs regular upkeep to keep it at that level.—RJH (talk) 15:37, 8 May 2008 (UTC)

Age of Mercury

How old is Mercury? The articles on Sun and Earth claim their respective ages to be nearly same 4-5 billion years. So I guess, Mercury too must be a twin.Anwar (talk) 20:15, 7 May 2008 (UTC) Rocks on Mercury have not been available, so no direct answer can be given. —Preceding unsigned comment added by (talk) 11:14, 20 May 2008 (UTC)


The source cited for the axial tilt gives a value of "~0", rather than 0.01 as listed in the article body. So it is unclear where that value came from. The conclusion of the following reference gives a value of 1.6 arcminutes for the mean obliquity:

Rambaux, N. (2004). "Theory of the Mercury's spin-orbit motion and analysis of its main librations". Astronomy & Astrophysics. 413: 381–393. doi:10.1051/0004-6361:20031446. Retrieved 2008-05-21.  Unknown parameter |coauthors= ignored (|author= suggested) (help)

That would correspond to 0.027°. Does anybody have a better reference? If not perhaps the article should use the above? Thanks.—RJH (talk) 16:07, 21 May 2008 (UTC)

P.S. I wonder what is wrong with the doi field that it doesn't complete the URL properly?—RJH (talk)

I added two sources that list the axial tilt as approaching zero - a JPL page that lists it as zero, and a journal that lists Mercury as having "No axial tilt". Whether that means "No appreciable axial tilt" is unclear. Let me look at this ref and see if I can correlate the three. UltraExactZZ Claims ~ Evidence 19:34, 23 May 2008 (UTC)
1.6 arcminutes is pretty close to no axial tilt; that's near the limit of resolution of the human eye. But it's still good to be accurate.—RJH (talk) 19:43, 23 May 2008 (UTC)
Absolutely. I'm shifting refs now. UltraExactZZ Claims ~ Evidence 19:46, 23 May 2008 (UTC)

Greek letters

Multiple astronomy articles present ancient Greek names for the objects, including Sirius, Venus, Mars, &c. For some reason, editor "Rubble pile" has taken a special interest in removing the Greek name from this article. Is there a consensus for the removal of the Greek name from this page in particular? I do think we should have a consistent policy about this across wikipedia. Thank you.—RJH (talk) 15:37, 27 May 2008 (UTC)

Can't see a reason to delete them. Serendipodous 16:06, 27 May 2008 (UTC)
I see no need to include the original names in Greek rather than the transliterations. Seems like trivia to me rather than encyclopedic content. We don't include the native name of the planet in any other languages, why Greek? Besides, we only seem to have one of the original Greek names anyway (the planet had two names in Greek). Kaldari (talk) 16:15, 27 May 2008 (UTC)
Patently untrue. Venus#Venus_in_human_culture, Mars#Historical_connections, Jupiter#Human_culture and Saturn#History_and_exploration list the planetary name in multiple languages, including Greek. The names are present because they were culturally important.—RJH (talk) 18:47, 27 May 2008 (UTC)
Aren't we talking about Mercury here? Besides, the transliteration is completely adequate for our uses. Why would we need to also list it in the native script? What's wrong with just listing the Greek names as Stilbon and Hermaon? I don't suspect that many of the people reading this article can actually read Greek script. Kaldari (talk) 18:50, 27 May 2008 (UTC)
Sorry, I misread your message. *sigh* However, there are still numerous examples of both the original greek and the transliteration (such as Galaxy and Milky Way) If a reason is needed, then I suppose for fact checking of the transliteration and also for consistent web searches. I see no problem with including both.—RJH (talk) 18:59, 27 May 2008 (UTC)
Isn't the fact that we only have a native Greek version of one of the names a problem? Anyone know how to write Hermaon in Greek script? Kaldari (talk) 19:28, 27 May 2008 (UTC)
And don't forget the cuneiform letters for the Babylonian name in the previous paragraph.Rubble pile (talk) 19:35, 27 May 2008 (UTC)
Good luck with that one! Kaldari (talk) 19:38, 27 May 2008 (UTC)
If we find a means to include the alternative Greek name, then I see no reason not to do so. I've seen articles with two forms. Likewise, the Sirius article includes the heiroglyphic version of it's name. I'm sure there is somebody out there who could supply the Babylonian rune in time. So I'm still not seeing a problem, as long as we're consistent.—RJH (talk) 22:01, 27 May 2008 (UTC)
We're not consistent at all. Some articles have planet names in Kanji, some have Greek, some have nothing but English transliterations. Even within this one article, we're not consistent. We have the native Greek version of one Greek name, a transliteration for another Greek name, and the Anglicized versions for 2 more Greek names. If you want consistency, I would suggest reverting back to Rubble pile's edit as a good start. Also, it's trivial information. An English encyclopedia article doesn't need the cuniform, hieroglyphic, Greek, Kanji, and Braille versions of every planet name. If you want that, we should start a list article to list all of them, not just the one or two that seem interesting to us. Kaldari (talk) 22:51, 27 May 2008 (UTC)
Furthermore, statements such as "the planet is called X in Greek" should be cited to a reliable source. If the reliable source gives a transliteration of the Greek we can trust it to be an accurate transliteration. Hence, we would only need the Greek letters "for fact checking of the transliteration" if the reliable source didn't provide one. Rubble pile (talk) 00:25, 28 May 2008 (UTC)
If anyone is still interested, Hermaon (a variant form of Hermes) is the transliterated version of Ἑρμάων. Reference: H.G. Liddell and R. Scott (1996). Greek–English Lexicon, with a Revised Supplement (9th edition ed.). Oxford: Clarendon Press. pp. p690. ISBN 0-19-864226-1.  Unknown parameter |coauthors= ignored (|author= suggested) (help) --Dr pda (talk) 11:26, 28 May 2008 (UTC)
Thank you. Unfortunately the font set on my PC isn't displaying the first character properly.—RJH (talk) 14:39, 29 May 2008 (UTC)

[De-indenting] Citing to a reliable source is a different issue than removing the Greek name because a transliteration exists. The citation issue is a problem for much of this article. In other astronomy articles the citation does exist. Simply adding a {{Fact}} tag should suffice for now.

Yes we should be more consistent. No I don't agree that deleting the name is the best way to achieve that. I would like this discussion to include the people who put the Greek name there in the first place. At this point I don't think we have enough opinions to form a proper consensus.—RJH (talk) 15:17, 28 May 2008 (UTC)

I don't really object to the Greek so long as we're actually consistant, and it doesn't turn into a list of names in other languages. Kaldari (talk) 15:29, 28 May 2008 (UTC)
I'm not sure whether there's a consensus on that, but perhaps this whole issue should be covered in the MoS? Sometimes the names in other languages have historical cultural aspects (such as Arabic names of stars), so it probably makes sense to include them. But just copying a name that's already in the Languages box along the left wouldn't make sense otherwise.—RJH (talk) 15:42, 28 May 2008 (UTC)
The name Mercury is taken from the Roman Mercurius, which was in turn adapted from the Greek Hermes, which was in turn adapted from the Babylonian equivalent whose name I can't remember. So yes I'd say that the Greek name for Mercury is of encyclopedic import. Serendipodous 15:07, 29 May 2008 (UTC)
I've cleaned up the wording a bit in the article. Let me know if that looks acceptable to everyone. Kaldari (talk) 17:07, 28 May 2008 (UTC)
It looks good to me. Thank you.—RJH (talk) 16:45, 29 May 2008 (UTC)

Geology of Mercury

If the problem of the geology section is one of comprehensiveness, then surely the Geology of Mercury article should be re-merged back into this one? Serendipodous 20:02, 1 June 2008 (UTC)

I think that might go a little far, but there's definitely some good material there that can be added here. UltraExactZZ Claims ~ Evidence 01:16, 3 June 2008 (UTC)
I've added some items (and refs) from the Geology article to expand this one. Some of the paragraphs were redundant - obviously this article was paraphrased from that one - but the structure was helpful. I also split the temperature items from Geology, and combined them with Atmosphere for a "Surface Conditions" section. UltraExactZZ Claims ~ Evidence 13:16, 3 June 2008 (UTC)

August 2006 Version

Just for reference here is the August 25th 2006 version. It only used 23 references. -- Kheider (talk) 03:33, 2 June 2008 (UTC)

For comparison, we just broke 100 references today. Considering that this article was promoted in May 2006, that's impressive. UltraExactZZ Claims ~ Evidence 14:46, 3 June 2008 (UTC)

Internal Structure

This section seems to be the biggest challenge, apart from the magnetosphere. It's tagged for cleanup and expansion, but I can't see a real good way to expand it. Most of the items I'd add are already referred to under Surface Geology and similar sections, so no need to duplicate those items here. As for cleanup, everything is referenced, and the section flows linearly from crust to core. Any ideas on how to clear these tags? UltraExactZZ Claims ~ Evidence 14:48, 3 June 2008 (UTC)

I don't really see how it could be expanded. It seems fine to me. Serendipodous 17:51, 3 June 2008 (UTC)

The Observation section

could probably do with an image like this, since it focuses on naked eye observation. The transit image was better suited to the ground based telescope section. As for the extra Mariner 10 image, I couldn't find a place for it, so I ditched it, if that's OK. Serendipodous 17:51, 3 June 2008 (UTC)

The only public domain(ish) image like that I can find is a photo in a NASA article here. Would that work? UltraExactZZ Claims ~ Evidence 18:24, 3 June 2008 (UTC)
It's difficult to know, since it's probably copyright of the photographer. Still, if its status can be determined I think it would work. Serendipodous 18:28, 3 June 2008 (UTC)
  • The Xackobo image was taken on 2002-May-04 when Mercury was in the evening sky with an elognation from the Sun of 20.9°, APmag 0.40, 0.85AU from Earth, Phase: 38%.
  • The NASA (Jeff Beal) image on 2006-Feb-13 was also in the evening sky with an elognation from the Sun of only 12.9°, APmag -1.07, 1.21AU from Earth, Phase: 88%. (Maximum elognation during that orbit was 2006-Feb-24 at 18.1°.)

If all else fails I can get a picture of it on July 1st (elognation 21.8°) with my Canon EOS 300D using a Canon EF 50mm lens. -- Kheider (talk) 19:11, 3 June 2008 (UTC)

That'd be the best option, I think. I can't tell if the Bulgarian image is free or not, but I'm reasonably certain that the NASA image isn't. It'd be nice to have a free image for that section. UltraExactZZ Claims ~ Evidence 19:36, 3 June 2008 (UTC)

"lobate-shaped colour units"

Does anyone have a clue what that means? Serendipodous 22:39, 3 June 2008 (UTC)

...Lobe-ish, maybe? It's unclear. UltraExactZZ Claims ~ Evidence 15:17, 4 June 2008 (UTC)
Lobate-shaped means it has a lobe, as in a lava flow. I'm not sure what the "colour units" was meant to communicate, but perhaps the ground has a different hue than the surroundings? I've sometimes seen that on moon shots when the surface colors get exaggerated.[7] Still, it's pretty unclear.—RJH (talk) 17:08, 4 June 2008 (UTC)
As I can remember this referes to the results of Mariner's 10 image reprocessing. It showed that some units in the smooth planes have lobate shapes resembling lava flows. This units are slightly different in color from their surroundings. Ruslik (talk) 18:34, 4 June 2008 (UTC)


Why can't this article be edited? I want to add Fahrenheit temperatures and links to Celsius conversion. —Preceding unsigned comment added by (talk) 20:38, 7 October 2008 (UTC)

The planet articles attract an inordinate amount of vandalism. Since it's already a Featured Article, there isn't much that needs to be done, except updating as new data is delivered from Messenger. (This might be reason to unprotect at some date.) As for your edits, we don't normally use imperial units in scientific articles. kwami (talk) 20:42, 7 October 2008 (UTC)

Downer about the vandalism. However, I feel that the average American reader would benefit from adding Fahrenheit temperatures. Very few Americans use Celsius or Kelvin(unless they are employed in scientific research). —Preceding unsigned comment added by (talk) 20:38, 7 October 2008 (UTC)

You can read WP:UNITS to understand Wikipedia policy about units of measurement. Basically, it's metric units unless necessary otherwise. The English language Wikipedia is not an American wikipedia -it is an international encyclopedia written in English. I personally however would not disagree about having Fahrenheit units too -provided it is discussed and becomes a style consensus. --Cyclopia (talk) 13:50, 9 October 2008 (UTC)
Science uses metric, no matter where it's based, so scientific articles reflect that. Serendipodous 13:56, 9 October 2008 (UTC)

To quote: "Conversions to and from metric units and US or imperial units should generally be provided. There are some exceptions: Articles on scientific topics where there is consensus among the contributors not to convert the metric units, in which case the first occurrence of each unit should be linked. "

But why would there be a "consensus among the contributors" not to add Fahrenheit conversions? It would help people to understand the article. Wikipedia isn't an encyclopedia whose audience is composed exclusively of scientists. It would make the article more useful to a wider audience. Just because Americans aren't the exclusive users of Wikipedia doesn't mean that the encyclopedia shouldn't be equally accessible to them. Tuna Night (talk) 15:48, 9 October 2008 (UTC)

Truth be told, when I'm editing a scientific article these days I don't even bother with Centigrade. I use Kelvins instead. Serendipodous 15:50, 9 October 2008 (UTC)
I think that indicating temperatures in Celsius can be of value for users -after all, Kelvins are used almost exclusively in a scientific context. As for Fahrenheit, I am in doubt. On one hand, converting units can be of help for the American public. On the other hand (1)SI units are an international standard, and it's United States problem not having adopted them. Wikipedia should adopt international standards as much as possible (2)Allowing Fahrenheit conversion would lead to a slippery slope, where everyone could legitimately claim to have each measurement translated in its favourite units system. I personally would use Celsius everywhere, and Kelvin where relevant.
Also: if the discussion continues it should be moved to the correct place -that is, WP:UNITS discussion. --Cyclopia (talk) 20:31, 9 October 2008 (UTC)

This discussion has been moved to WP:UNITS, as suggested by Cyclopia. Tuna Night (talk) 18:01, 10 October 2008 (UTC)

The text of MOSNUM contains no language which would prohibit such conversions, and there is no consensus to omit them. They should be included; our purpose is to communicate with our whole readership, not compel them to read SI whether it tells them anything or not. Septentrionalis PMAnderson 05:58, 13 October 2008 (UTC)
MOSNUM does allow for use of metric only, if editors agree on such an action. The discussion regarding this was at Talk:Saturn. --Ckatzchatspy 07:51, 13 October 2008 (UTC)
Yes, indeed it does; if this were the Crab Nebula, I would join a consensus to so agree. But this talk page does not demonstrate such a consensus. Septentrionalis PMAnderson 17:52, 13 October 2008 (UTC)
  • The difference from Saturn is that human beings cannot stand on Saturn; but the temperatures in the lead may be of interest about possible real or fictional colonization of Mercury. The temperatures of formation later in the article should not be turned into Fahrenheit; but then they shouldn't be given in Celsius either; the subtraction of 273 produces spurious precision. Septentrionalis PMAnderson 19:17, 13 October 2008 (UTC)
You could conceivably build floating cities in Saturn atmosphere, so the two bodies are on par on this subject. Also, I don't understand why a temperature is "more interesting", as you seem to imply, if related to colonization. I can't also understand how a subtraction could produce "spurious precision". --Cyclopia (talk) 00:32, 14 October 2008 (UTC)
2500 K is (almost exactly) 2227 C; but about 2500 K implies that the figure has been rounded to the nearest 100, or possibly 500, degrees, and therefore that the value is no more precisely known than that. About 2227 C implies precision of a degree or two. Thus the two phrases differ, in one dimension, by two orders of magnitude. Septentrionalis PMAnderson 03:56, 14 October 2008 (UTC)
  • Along the same lines, recall the old joke about the museum guide who said the dinosaur was 70,000,006 years old: he'd been told it was seventy million years old when he was set to giving the tour, and he'd been doing so for six years. Septentrionalis PMAnderson 04:00, 14 October 2008 (UTC)

surface temperature

The summary info (in the side box) gives mercury's mean surface temp at two latitudes as 340K (equator) and 200K (high latitude). The main article gives the (presumably global) mean surface temp as 442K, with reference to a NASA fact sheet. Someone care to research and resolve the apparent discrepancy? The "average" can mean a lot of different things... —Preceding unsigned comment added by (talk) 00:37, 8 October 2008 (UTC)

Mercury in science fiction

I think the main article could be improved if there were a link to a list of science fiction books and movies dealing with the planet Mercury, or involving Mercury in some way.

For instance, I seem to remember a movie that came out a couple years ago, where some researchers were traveling towards the Sun, and they stopped in at Mercury. What was the name of that movie? I wish I could remember. (talk) 07:12, 9 October 2008 (UTC)

there is. Serendipodous 07:50, 9 October 2008 (UTC)
Thanks. The film I was wondering about, is Sunshine (2007 film). (talk) 20:13, 10 October 2008 (UTC)


The full set of phases of Mercury were suspected for some time before 1639. —Preceding unsigned comment added by (talk) 16:25, 24 October 2008 (UTC)

Cemical composition of the atmosphere

Which gas is the most common in the atmosphere?

2008-12-04 Lena Synnerholm, Märsta, Sweden. —Preceding unsigned comment added by (talk) 14:25, 4 December 2008 (UTC)


I noticed that with other planets we are brought automatically to their page instead of their disambiguation. Perhaps Mercury should follow suit? (talk) 17:37, 30 November 2008 (UTC)

Mercury's disambiguated because although the other ancient planets are the most prominent use of their name, with only the Roman gods to take second place, Mercury has to compete with the element mercury. --Patteroast (talk) 14:30, 4 December 2008 (UTC)

Confusing note

Sorry if this is obvious to everyone else, but this note seems a bit hard to parse: "1/30 is the fractional equivalent to 2.1′." Perhaps it would make more sense if it were written out, like "1/30 of a degree is the fractional equivalent to 2.1 arcminutes." Kaldari (talk) 19:21, 6 June 2008 (UTC)

That would make a great deal more sense. No objection from me. UltraExactZZ Claims ~ Evidence 19:43, 6 June 2008 (UTC)
Done. Kaldari (talk) 20:27, 6 June 2008 (UTC)
On a point of simple arithmetics, 1 degree is precisely 60 arcminutes, therefore 1/30 of a degree is exactly 2 arcminutes. So where does 2.1 come from? DS212.2.2.5 (talk) 09:41, 25 June 2008 (UTC)
2.1 is approximatelly 1/30. Ruslik (talk) 10:12, 25 June 2008 (UTC)
One couldn't disagree with that statement. Then you concur that the use of "equivalent" is incorrect. The note links to "Orbit and Rotation", para 3, perhaps that para should state "approximately 1/30". DS212.2.2.5 (talk) 12:29, 25 June 2008 (UTC) —Preceding unsigned comment added by (talk) 12:27, 25 June 2008 (UTC)
1/30 of a degree is exactly 2 arcminutes, whereas 1/29 of a degree is 2.07 arcminutes. So I'd suggest the latter because it is slightly more accurate.—RJH (talk)

I would like to suggest changing all of the following sentences:

  • "Functionally, Mercury’s axial tilt is nonexistent, with measurements as low as 0.027°." to "Functionally, Mercury’s axial tilt is nonexistent, although it has been measured precisely as 2.11′ ± 0.1′(0.035° ± 0.002°)."
  • "This means an observer at Mercury’s equator during local noon would never see the Sun more than approximately 1/30 of one degree north or south of the zenith." to "This means an observer at Mercury’s equator during local noon would never see the Sun more than approximately 1/29 of one degree north or south of the zenith."
  • "Conversely, at the poles the Sun never rises more than 2.1′ above the horizon." to "Conversely, at the poles the Sun never rises more than 2.1 arcminutes above the horizon."

Kaldari (talk) 18:03, 25 June 2008 (UTC)

The phrase "functionally" seemed odd (what is the "function" of orbital tilt?) so I changed this to be "nearly zero", more in line with what Kaldari suggested.
There was a very odd point made that "an observer at Mercury’s equator during local noon would never see the Sun more than approximately 1/30[a] of one degree north or south of the zenith.". Well, I guess this is technically true, but of course an observer 1/30th of a degree off the equator-- that is, roughly a kilometer away-- would see the sun exactly at zenith. I don't really see why anybody would be interested in distinguishing the precise difference between what an observer would see at the equator versus at a point a kilometer off the equator, so I deleted this. Also, the point about the sun never rising more than 1/30 of a degree at the poles is true, but it's worth noting that the diameter of the sun from Mercury is about a degree, so it's worth noting that this refers to the center of the solar disk-- the edges of the disk do rise above the horizon. (for a flat Mercury). Geoffrey.landis (talk) 16:50, 27 January 2009 (UTC)


The introduction seems to lack any mention of the October 2008 Messenger pass and how much that mapped. (talk) 23:26, 1 November 2008 (UTC)

No offense intended, but to me the lead seems unbalanced in its coverage and doesn't quite satisfy WP:LEAD. There is an entire paragraph on ancient beliefs and half a paragraph on spacecraft. By contrast, there is no coverage of historical telescope observations, the plains section, spin orbit resonance or, perhaps most notably (at least to me), the advance of the perihelion. I think the missing topics should be summarized and the overemphasized subjects toned down.RJH (talk) 17:52, 3 February 2009 (UTC)
I made some additions to the lead in an attemptto better satisfy WP:LEAD. There's a separate paragraph on exploration now, and hopefully that can be updated with Messenger news.—RJH (talk) 20:10, 10 February 2009 (UTC)

Mercury vs. Venus

Am I mistaken in believing that there is some confusion between the second paragraph in Mercury (planet)#Ancient astronomers and the second paragraph in Venus#Historic_understanding? For example, both list Phosphoros as the name for the "Morning Star", presumably in reference to the current article. The text from 'In Latin, the word "Lucifer",' onward (in this article) could just as easily be plunked down on the Venus article. It seems squirrely to me.—RJH (talk) 23:47, 24 February 2009 (UTC)

I was bold and removed this text from the article until its conection with Mercury can be substantiated.:

In Latin, the word "Lucifer", meaning "Light-Bringer" (from lux, lucis, "light", and ferre, "to bear, bring"), is a name for Venus in its dawn appearances, since it preceeds the sun. The Latin Vulgate version of the Bible used this word twice to refer to the Morning Star: once in 2 Peter 1:19 to translate the Greek word "Φωσφόρος" (Phosphoros),[1] which has the same literal meaning of "Light-Bringer"; and once in Isaiah 14:12 to translate "הילל" (Hêlēl), which also means "Morning Star".

Sorry.—RJH (talk) 18:56, 1 March 2009 (UTC)

Radius and Volume Values on the Planet Pages

This is a concern regarding all the planet and planetoid pages, but I don't know where ot post such. If anyone knows where this comment is better suited, I'll copy it there. Regarding the planet (and minor planet) pages, should we add a reference regarding the formulas used in calculating the following? "Mean Density" -- do the pages use Wikipedia Page definition for "Mean Density" (R1 = (2a+b)/3 -- a being Equatorial [or longest] radius; b being the Polar [or shortest] radius)? Or are the pages using another formula (e.g., an average between axes (a+b)/2? Regarding Radius, and its affect on Volume, are the Volume values calculated using the Volumetric Radius (yet another radius calc), or Mean Radius, or Average Radius? "Volume" -- The Volumetric Radius (R3 = the CubeRoot of a2b), is used to determine Volume for "spherical" ellipsoids (i.e, those with a relatively circular equatorial zone -- hence, a relatively constant a axis value, and a different b axis value. For irregular shapes (planetoids [most asteroids, many minor planets], and satellites [moons]) require more-complex formulas to determine Volume. The radii around their "equatorial" or "polar" region are not constant -- lumps, bumps, cookie-dough shaped irregular "spheres", etc. Bottom line to my rambling ... I think we need to be consistent in our labeling. If the pages show "Mean Radius" or "Volume", one standard appraoch should be used. Since many technical astronomical sources are inconsistent, it may be a challenge. Still, I think the page(s) should note what formulas are used for such (or, at the very least, reference if a certain page is using a different [non-Wikipedia-defined] formula. My assumption is if a planet page uses the term "Mean Radius" or "Volume", it will agree with the Wikipedia page defining "Mean Radius" and "Volume" calcs for planets, planetoids. Tesseract501 16:28, 4 March 2009 (UTC)

Thank you for bringing this up. My suggestion is to take this up on Wikipedia talk:WikiProject Astronomical objects. This would impact all of the planet pages, so WP:ASTRO is a good place to get consensus, at least among the astronomy buffs.—RJH (talk) 00:45, 4 March 2009 (UTC)
Mean density of Mercury was not calculated, it was taken from the cited source. When the dimensions and mass of a body are known, it is usually possible to find a reliable source for the density. In other cases calculations are sometimes used as crude estimates. Ruslik (talk) 14:45, 4 March 2009 (UTC)

water vapor

I think something's logically not right with this sentence:

Water vapor is present, being brought to Mercury by some combination of processes such as: comets striking its surface, sputtering creating water "where none existed before from the ingredients of solar wind and Mercury rock" (both contain hydrogen and oxygen), and "reservoirs of water ice in small areas of Mercury's poles where local topography creates permanently shadowed spots in crater walls that might trap water over the age of the solar system"

Reservoir of water ice is not a process. Also, how can it be brought out of ice if it says it can be trapped forever? I know that ref says it but it's not a peer-revieved scientific literature, just news, while peer-reviewed paper, based on the abstract, doesn't mention the third possibility.--Adi4000 (talk) 08:31, 9 November 2008 (UTC)

Yes I agree, that does need fixing. Possibly it was intended to mean that some of the trapped ice is steadily being released by some external process, such as impacts. But that is speculation.—RJH (talk) 23:06, 9 March 2009 (UTC)

Closest approach

I have a question about the following:

Mercury can come as close as 77.3 million km to the Earth, but currently it does not come closer than 82 million km from the Earth.

First, it uses the word "currently", which has a chronological dependency. (See Wikipedia:MoS#Precise_language_for_dates.) Second, the [72] citation only appears to give the dates of closest approaches. It does not give the distance of closest approach this year. In fact, I see no data between 1983 and 2012. Thus the origin of the 82 million km value is something of a mystery to me. Any ideas? Thanks.—RJH (talk) 20:33, 10 February 2009 (UTC)

That was probably my edit. Sorry for the imprecision. I was checking the accuracy here with Solex. From -40,000 to 50,000 Mercury never approaches the Earth closer than 82 Gm until 4487. And never closer than 79.2 Gm.
I compared some of the other planet pages on that site with Solex. They evidently do not calculate the closest approaches the bodies make over a time frame. Saros136 (talk) 08:37, 14 February 2009 (UTC)
Actually Ref 73 "Mercury Elognation and Distance" is me. The bottom of that reference shows that between 1969 and 2153 Mercury never comes closer than 0.5489AU (82 million km). -- Kheider (talk) 12:59, 14 February 2009 (UTC)
Thank you for the clarification.—RJH (talk) 20:00, 16 February 2009 (UTC)

In an effort to come up with another source, I asked about this minimum approach issue at Gravity Simulator and frankuitaalst came up with a 1,000 year chart. Since this is a Featured Article I am not if we can use it as a primary source. Though over at Mars#Orbit_and_rotation we do use an article written by the author of Solex (Ref 68: Mars' Orbital eccentricity over time). -- Kheider (talk) 22:21, 1 March 2009 (UTC)

In fact, Solex has been used many times as a source, usually by me, and usually in asteroids and transit articles. I added it here. I always mention it in the comments, but have not always cited it. Saros136 (talk) 01:20, 3 March 2009 (UTC)
Hi Saros136, I don't doubt your results, I just know the requirements for Featured Articles are more demanding then they are for asteroid stubs. I have changed the reference to point to all 3 sources since they do help back one another up. -- Kheider (talk) 02:04, 3 March 2009 (UTC)
I wrote this just before reading your response. So I'll write it anyway.
There were two typos in my addition, now fixed. This explains the criticism at the other forum. The calculation holds with starting positions for DE200,409,or421. But I should first introduce Vitagliano.
I wrote before in a Mars discussion ... Actually, the creator of SOLEX, Aldo Vitagliano, is a leading expert in the subject. One of the true orbital wizards. He was the one who determined the date the last Mars close approach nearer than the 2003 one. No less than the legendary Jean Meeus had invited him to collaborate on When Was Mars Last This Close? which goes into the changes of Mars' eccentricity very thoroughly. In fact the renowned Myles Standish, of JPL, was going to make the calculation, but dropped it after communicating with Vitagliano "Because of my confidence in him and his research,..." [3]. Meeus and AV have worked together on other long-term investigations, such as future simultaneous transits of Venus and Mercury.
And the long term accuracy, according to Vitagliano, is very great. He would disagree very strongly with the one at the gravitorium forum who only trusted long term predictions to 1,000 years. Solex has been extensively tested (documentation in the help file of Solex). As good as JPL. That is no accident (it is calibrated to work from JPL).
His website explains it very well. Here is a more technical paper by him explaining it [8] Saros136 (talk) 02:30, 3 March 2009 (UTC)

Yes, I can adjust the comment. But when the GravSim people were looking at the wiki-typo the two programs would obviously NOT produce the same result. Now that the typo is fixed the two programs do seem to agree quite well. I would put GravSim on the same level as Solex. There can be no long term accuracy with typos. This is part of the reason wiki is not a fan of {{OR}}. Thank you for double checking your numbers. -- Kheider (talk) 02:50, 3 March 2009 (UTC)

Thanks for saving the day by double checking this. Yes, my typos created the appearance of a discrepancy until it was realized that the Solex result was misrepresented. I don’t see the connection between typos and OR, though, since they are just as likely with non-OR.
With non-OR (say a peer-reviewed paper) it is generally a lot easier for someone to look it up and catch the typo. The most important thing is that something can be verified. And thanks to all 3 programs we can safely say that Mercury will be coming closer... -- Kheider (talk) 00:16, 5 March 2009 (UTC)
Well, this is a non-OR source and edit. As for ease...a Solex user could reach any one of those dates from the start menu in seconds. One given just the year, as in this case, would need a second or two to use the minimum distance function. The secret is that Solex stores positions at (intervals of decades) over a very long time, to be used the starting positions The number depends on the version and chosen option. Running through a range takes longer, but the program is running in the background.
The fastest calculations are made by a program using the analytic method. Those use explicit algebraic and trigonometric equations. The minimum distance from my offline version of, giving six decimal places, matched Solex exactly for the 4487 approach, after the latter was rounded.
To make is obvious there are no typos, I could have posted the files or a screenshot of it in my Google account. Importing it in a google spreadsheet would make it easy to count approaches.
The speed of checking an article or book depends on how long it takes to obtain it, and that is not always possible. Saros136 (talk) 07:36, 8 March 2009 (UTC)
As for OR, I thought there was a fair chance that someone would object on OR grounds, so I read, not for the first time, the definition of OR and the policy. I was convinced that this research was in line with it. Writing on OR doesn’t cover the case where no one had previously published the information, but an expert provided the program, which was an expert source that published, in a sense, the numbers to a computer file. But policies have to be adapted, and here is can be done while staying true to the OR policy. None of the objections apply to this source. It looks to me the question would be how I used it. My actual time frames and benchmarks were my choice, but this is only original in a trivial way. To count close approaches of planets and group them, or determine the gaps in time is a very unoriginal thing.
By the way, here a great result: the minimum approach value from GravSim in the next 1,000 years is 82,080,535,160 m Solex gave 82,079,957,000 . The difference comes to 1 part in 140,000. And this is for the year 2942. Saros136 (talk) 10:11, 4 March 2009 (UTC)

Frank over at GravSim did an awesome chart of the change in inclination and eccentricity of Mercury over the next 20,000 years. -- Kheider (talk) 00:14, 5 March 2009 (UTC)

Chemical composition of the atmosphere

Which gas is the most common in the atmosphere?

2009-03-10 Lena Synnerholm, Märsta, Sweden. —Preceding unsigned comment added by (talk) 13:28, 10 March 2009 (UTC)

Have you looked at the atmosphere section at the bottom of the infobox?—RJH (talk)
I think you misunderstand the question. He isn't asking what chemical is most common, but what cemical. ;-)-- (talk) 05:52, 24 March 2009 (UTC)
Okay, well first your reply makes no sense to me. Secondly, the infobox table does include chemical compounds, if that is what you were trying to say. I'm not certain about the hydrogen though; maybe any H2 molecules get dissociated by UV? :-) —19:08, 24 March 2009 (UTC)
Sorry, I missed the "joke".—RJH (talk) 22:40, 24 March 2009 (UTC)

Excuse me, but I am in fact a woman. I did not intend to joke, I just missed the infobox.

2009-03-29 Lena Synnerholm, Märsta, Sweden. —Preceding unsigned comment added by (talk) 15:54, 29 March 2009 (UTC)

Sorry, by "joke" I meant the remark by anonymous editor about a minor typographical error in the section name. I did not take your post as a joke.—RJH (talk) 17:56, 29 March 2009 (UTC)

Mercury orbit picture misleading


While the Earth's orbit often is drawn as a circle, Mercury's is too eccentric. Especially a picture that purports to show Newtonian motion (faster near the sun), it would be proper to have an elliptical orbit drawn. This is exacerbated by having Mercury be of different sizes, which (combined with the actual circle) creates an illusion of some kind of perspective. —Preceding unsigned comment added by Gwrede (talkcontribs) 08:12, 24 March 2009 (UTC)

Problem is, Mercury's ellipse is 98% as wide as it is long. A circle with the Sun slightly off to one side. The one in the Spin–orbit resonance section is exaggerated to make the point. Saros136 (talk) 10:10, 24 March 2009 (UTC)

Verifying SOLEX

Further to the talk above in section "close approach cite", and following on from my request for clarification on the article, I also went to try out SOLEX for the first time. I only looked at trying to verify the close approaches claims up to 3000, and in brief I am satisfied the claims are both verifiable and, for what I checked, verified. The rest is a long post so I've wrapped it a hide template.

84user (talk) 22:06, 30 March 2009 (UTC)

Thanks so much for helping. The small difference in time is because that Horizons option factors in light time and gives the apparent close approach, whereas Solex doesn't. I used the vector option, and made sure I did not have another switch on that would have brought light-time in. I had to calculate the distances in Excel. The agreement is much, much better. Saros136 (talk) 07:14, 31 March 2009 (UTC)
I just did AD 871. The agreement was to the second. I'll post. SOLEX gives 871/5/10 00:47:24 to it Saros136 (talk) 07:57, 31 March 2009 (UTC)
And here it is. Asterisks in the a column mark the closest. The columns after the date give the X,Y, and Z vectors. Then use the formula, square root of the sum of the squares, to get the distance at the far right. Saros136 (talk) 08:30, 31 March 2009 (UTC)

Do you know what values Solex uses for GM? -- Kheider (talk) 23:10, 1 April 2009 (UTC)

Variable, since by default it models solar mass loss. He nowhere mentions G, but does give the solar mass. But given the stunning agreement with Horizons, I'd say any differences in the physical values adopted make no difference. Saros136 (talk) 03:48, 3 April 2009 (UTC)

Contents of the exosphere

The section on the exosphere includes 2 different lists of what it is comprised of. This is both redundant and confusing. Any ideas for how to rewrite this section? Kaldari (talk) 22:31, 30 March 2009 (UTC)

Untrue statement

"It can only be viewed in morning or evening twilight." This can't be right. If it can be up to 28o from the sun, then for some parts of Earth's surface it can be visible when the sun is 28o below the horizon, and it can be up to 10o above the horizon when the sun is at least 18o below the horizon, at least in the tropics. (talk) 14:54, 2 April 2009 (UTC)Nightvid

30° corresponds to two hours of the Earth's rotation. Also you usually want an object to be at some elevation above the horizon to see it clearly. So at best you'd see it within 1–2 hours before sunrise or after sunset, and that is only when the ecliptic is approaching a perpendicular to the horizon.—RJH (talk) 19:30, 2 April 2009 (UTC)

close approach cite

I removed the reference to the JPL info, because it is not relevant. It covers less than 1 part in 240 of the time span involved, and lists none of the threshold marks or the count of approaches.

The other cite is a problem. It doesn’t actually confirm the actual numbers, and does not go to the past. But the real issue here is that while the graph of the approaches is fine, the other graph is misleading and supports an erroneous position, that the minimum distances are getting smaller because of changes in Mercury’s inclination and eccentricity. The biggest part, by far, of the change is the decrease in the Earth-Sun distance at the time of the closest approaches. I’ll elaborate in another post. And for the inclination, which is on the graph, it is indeed falling relative to a fixed J2000 reference frame. But as Frank said, the Earth’s inclination is changing. This is why the relevant numbers are for the mean ecliptic of date. Mercury’s inclination has been increasing throughout, and will continue to do so for 7,500 years. Saros136 (talk) 07:15, 30 March 2009 (UTC)

I rv'ed your edit to the multi-cite. I see no reason to remove useful info that can be reproduced by an average user and shows useful numbers in *THIS* lifetime. As far as GravSim "doesn’t actually confirm the actual numbers", I think a GravSim plot does a better job of showing the information and general trends than the (basically useless as readable reference) front page of the Solex website. -- Kheider (talk) 07:38, 30 March 2009 (UTC)
I could have been wrong. Since the cite listed those two among the sources generating the numbers, I just thought you wanted them for support or credibility. hence my comments: GravSim didn't prove that my actually number cited was correct, although it did support it in general. The JPL Horizons site, not only did not generate the numbers, but couldn't even verify in a small way. It turns out that there is a another problem with thew Horizons data: the top five list is wrong. It gave the minimum distances at midnight, not the actual close approach distances or times. The years are wrong: 2107 should replace 1969. Although I didn't use the Horizons site to find the problem, I just did use it to make a list for 1950-2200. I got batch jobs with the positions every 25 hours in those years. And then applied an Excel program I wrote to find the minimums and calculate the times of closest approach, using an interpolation formula from Meeus. (They broke it down into 24 emails. I used the vector form, to avoid corrections for light time, because Solex doesn't and I wanted to compare the times too. Calculated the distances from the XYZ coordinates) I should post the list (or one from another source), thus making the debate unnecessary. I should have posted it before, really, as I did with the Venus case. But note that using Solex alone found the error; it is not necessary to reproduce the results with the same source. Saros136 (talk) 06:46, 31 March 2009 (UTC)
Good catch Saros, since I was using a generic timestep of every 24 hours (00 UT) , and manually scanning the output with a text search, I missed the "2107-Jun-02 16:00" encounter at 0.548967AU. When I generated that list in May 2008, I was really only trying to validate the article statement "Mercury currently comes as close as 82 Gm to Earth". We have obviously come a long way since that (completely uncited) statement. -- Kheider (talk) 12:36, 31 March 2009 (UTC)
I doubt most people reading this have ever used Solex, I know I haven't. I have always wanted to, but have not got around to it. If you really want to defend your methods, perhaps you should produce a 10 step process on how to use Solex to re-produce some (if not all) of your results. I think that would be a BIG help in defending ALL Solex results against laments of a generic link to the front page of the Solex site. This is a featured article and all practical information should be provided. Do not assume that the reader has ever heard of Solex much less used it. -- Kheider (talk) 08:29, 30 March 2009 (UTC)
It is acceptable to use as a source a book or magazine not easily available to the readers. What counts is that those who would and can will be able to do it. In this case only a small minority would stop to run the simulation anyway. The page will make it easy to do that. And for all, they might get some confidence that a trustworthy source has been used. Saros136 (talk) 09:02, 31 March 2009 (UTC)
Oh trust me, I don't like it when someone quotes a book that is not available online because all I can do is shrug my shoulders and take their word on it.
All 3 are OR so now a can of worms is open. -- Kheider (talk) 17:19, 30 March 2009 (UTC)

JPL Horizons

To reproduce the JPL-Horizons results:
1. Go to
2. Click change on "Time Span", change to 1950-01-01 and 2160-01-01 and click "Use Specified Times".
3. Click change on "Table Settings", make sure only "10,13,20,23,29" are selected. (#20 is the important one.) Click "Use Selected Settings".
4. Click "Generate Ephemeris" to generate JPL RESULTS. (You will need to wait 2 minutes for it to generate)
5. Use "Ctrl-F" to find the values " .5490" and the value " .5489". The value " .5488" is not listed...
Thus, my results are reproducible using a reliable source.
-- Kevin Heider

I installed Solex 10. It looks like a great/useful program, but I am a newbie to it. I used "[J] to Jump to Date" and "[X] to Show Osculating Elements" In the year 3000, Mercury has an inclination=6.95, in 4000 i=6.88, 6000=6.77, 7000=6.71, 10000=6.55, 14000=6.36, and 17000=6.25 (Solex Screen grab for 17000AD). I fail to see support for your claim that "Mercury’s inclination has been increasing throughout, and will continue to do so for 7,500 years." It looks to me that the GravSim plot is correct. -- Kheider (talk) 21:02, 30 March 2009 (UTC)

There are options. D selects equinox of date. And the elements formulas for Meeus show a decrease in the eccentricity for the fixed frame, but increase in the inclination in using the mean equinox and ecliptic of date. The GravSim plot is correct, it is just not doing it in the right way. Saros136 (talk) 07:05, 31 March 2009 (UTC)

I think for a general article it might be better to use the current J2000 ecliptic as a reference point than to confuse the matter by going into too much detail about how the Earth's orbital plane also changes and the ecliptic in several thousand years will be mildy different. Otherwise you also need to plot (and explain) the change in Earth's inclination and explain that Jupiter is basically influencing everything. The plots were created to simplify the explanation (without being too technical). -- Kheider (talk) 22:28, 30 March 2009 (UTC)

I don't think it should be in the article or link at all, because the explanation is flat out wrong. The inclination has only a small effect in any case. Almost the whole thing is because of the change in the Earth-Sun distances at the best approach times, which happen near the inferior conjunctions with Mercury at aphelion. For a very, very long time there will be sub-80 Gm approaches, throughout both decreases and increases in inclination and eccentricies. The distance graph should be on a separate page. Saros136 (talk) 06:53, 31 March 2009 (UTC)
I disagree that the explanation is "flat out wrong". The graph shows what it needs to. It shows that Mercury's orbit is dynamic and that there is a complicated periodic exchange between eccentricity and inclination. I suspect that the closest approaches occur when both Earth and Mercury are near local peaks in eccentricity. This would be your "Earth-Sun distance". No single plot will easily show this because Earth pulls on Mercury as Jupiter pulls on Earth. -- Kheider (talk) 13:19, 31 March 2009 (UTC)
What has not been mentioned yet is the longitudes of the closest approaches. Of course they take place very near Mercury's aphelion longitude, but there is only a 25.5 degree difference between that and the Earth's longitude of aphelion. This is why, going back to way before the current decline, all the close approaches took place when the Earth was more than 1 au from the Sun. The gap between the aphelion longitudes is increasing, but this is very slow. The next very close approach with the Earth less than 1 au from the Sun is in 16868. Once that happens, it stays less than 1 au for a long time. And the records continue to fall.
Again we need to be careful with our results. According to my run with Solex 10 (I used [V] mode for adaptive stepsize), close approaches with a distance<82.1Gm and with the Earth<1AU from the Sun do not occur until the year 19873... -- Kheider (talk) 16:17, 1 April 2009 (UTC)
Yes, but not that careful. Both are examples of the same thing, the change to more favorable circumstances due to the changing of the longitudes of perihelion/aphelion.
For the record, I've saved every approach < 83.1 Gm from -50000 to 150000. I chose that cutoff after I discovered that that is one of the lowest thresholds represented throughout. Consecutive ones never appear more than 13 years apart. In every case, Mercury was at a much greater than average distance from the Sun. The Earth, however, varies all the way from perihelion to aphelion. Until 16868, the Earth was always> 1 au away from the Sun. Not favorable to extremely close approaches, but it happened because of the fairly large gap between the aphelion and perihelion longitudes. Eventually, it was possible for Mercury to be close to aphelion at inferior conjunction when the Earth was closer than average, a much more favorable situation. In my 200,000 year database, Mercury comes closer than 80 Gm 32,000 times, but never when the Earth is more than 1 au from the Sun. Saros136 (talk) 08:07, 3 April 2009 (UTC)
The Earth's declining eccentricity is also contributing to the decline. Declining eccentricity pulls in all the more distant points in the orbit. Much later, bigger eccentricity will favor closer approaches.
Both these effects can be quantified. Use the formula connecting semimajor axis a, e, true anomaly v (about equal to the longitude), and the distance. Compare using eccentricities of .02 and .0167 the high before the decline and current. And use 180° vs 155° The latter is more like today's longitude. Both make a huge difference. Saros136 (talk) 06:38, 1 April 2009 (UTC)
The effect of Mercury's eccentricity change gets overestimated. Because of the smaller orbit size, a .02 change in e makes less of a change in extreme distances than .01 on the Earth. The change is always a×e. And according the Meeus, the current change for Mercury is .000020407 per century and -.000042037 for the Earth. Saros136 (talk) 06:56, 1 April 2009 (UTC)
I ran a simulation is SOLEX with the inclination of Mercury set to 0° at 2000/1/1. It ran to 50,000. The inclination change did make a difference; the record was shaved by .206 Gm. The number from 2009 to 50,000 meeting my 83.1 threshold increased from 26,035 to 28,512.
To do it, choose an ephemeris the usual way to 2000. Then go back to the menu. Open, with notepad, final.ele. Change the inclination figure to 0. Save it. Then choose option 7, the full n-body file, and type in final.ele. Check to make sure the elements are changed to the desired number, and do it. Saros136 (talk) 08:31, 3 April 2009 (UTC)
Well do keep in mind that Earth currently has the most inclined orbit of all eight major planets relative to the Sun's equator (7.25°). So when it comes to inclinations a lot of this is simply perspective. We still live in a very geocentric society. The Suns equator and the Sun-Jupiter barycenter (Invariable plane;within 0.5° of the orbital plane of Jupiter) are both better long-term reference points. -- Kheider (talk) 16:54, 3 April 2009 (UTC)
Perspective changes, but positions don't. No matter what coordinate system is used to describe the positions of the bodies, it would be calculated that my fictitious Mercury passes between the Sun and the Earth every inferior conjunction, and that my change had minimized the distance. The elements were not geocentric. They used the J2000 reference frame. Are you saying there is something wrong or backward about the astronomer's choice of reference frames? Saros136 (talk) 03:32, 4 April 2009 (UTC)
We are discussing distances between the Earth and Mercury. The relevant inclination is that between the orbit of the two bodies. If we were discussing Pluto-Mars distances, then that would seem more relevant. Saros136 (talk) 04:00, 4 April 2009 (UTC)

For long-term simulations the Earth's passive and rapidly changing inclination/ecliptic (compared to Jupiter's semi-fixed inclination) may not be the best reference point since the Sun-Jupiter barycenter has a huge influence in the rate-of-change for both eccentricity and inclination. But we are diverging from the main point of this thread. I simply did not like you calling the "for demonstration purposes" inclination/eccentricity chart for Mercury, "flat out wrong", simply because we did not make a plot of the Earth's eccentricity/inclination change or go into detail explaining why changes in Earth's eccentricity could be more significant. And obviously, the ecliptic is Earth-biased by definition.-- Kheider (talk) 10:22, 4 April 2009 (UTC)

I'm sorry about the wording then. It wasn't directed just at the graph, but about the idea that the changes in inclination and eccentricity drove the decline. The angle between the planets has increased slightly, does not change much at all, and the degree of change is not the factor. It is the changing heliocentric distance of the Earth at the record approaches. And that is a function of the lowering eccentricity (for now) and widening gap between the longitudes of the aphelions of the planets. Here is a graph, of the change in the Earth distances and Mercury distances for the next 380 records, covering about 22,000 years . The distances in Gm, are compared with the average. Saros136 (talk) 06:42, 5 April 2009 (UTC)

Misleading picture

The picture at the beginning of the article shouldn't be a false color one. Maybe put that one in later on, but I think the first photo should be accurate. Knick99 (talk) 18:00, 5 April 2009 (UTC)

Why? This provides more information than an image based upon human visual limitations, and you wouldn't be able to view this scene from Earth anyway so it's not misleading.—RJH (talk) 18:33, 8 April 2009 (UTC)

Surface conditions and "atmosphere" (exosphere) section

I noticed that the temperatures given are in Kelvin; since we are not all scientists or engineers could a Celsius and/or Fahrenheit be given too? —Preceding unsigned comment added by (talk) 12:56, 19 May 2009 (UTC)

My thought is that most people have no problem getting the overall scale of Kelvins. For people that are more demanding, is it that difficult to look up kelvin and use a calculator? Listing numbers in multiple systems would clutter the article horribly. I wiki'ed K so that people can look it up quicker. -- Kheider (talk) 15:18, 19 May 2009 (UTC)
It's silly to use a scale that few people are familiar with. This article is read by kids too. I have noticed the preference of scientists to update Wikipedia articles and use Kelvins or other unfamiliar units and I think it detracts from the quality and readability of Wikipedia. Cshay (talk) 05:58, 18 August 2009 (UTC)
As a scientist myself, I say I agree with Cshay. It's easier for technical people to convert to Kelvin than for non-technical to convert to Celsius. WP:UNITS however seems to indicate only SI units and some exceptions not including the Celsius. I'll try to do some policy-digging and see. --Cyclopia (talk) 09:34, 18 August 2009 (UTC)
Digging WP:UNITS talk archives, it seems the best thing to do is to use both. I'd leave Fahrenheit away. I'll edit to provide Celsius conversions. --Cyclopia (talk) 09:42, 18 August 2009 (UTC)
Hmmm, I don't know how to do that without breaking the template. I've put the numbers as comments in the template, I welcome more skilled editors to help! --Cyclopia (talk) 09:53, 18 August 2009 (UTC)
This is why I don't like conversions. Your conversions seem to ignore significant figures. Why are you listing 380 K (2-3 sig figs) as 106.85 C (with 5 sig figs)?? -- Kheider (talk) 17:14, 18 August 2009 (UTC)
Since this is a scientific article, the usual preference is to use SI units. If the consensus was against providing metric to archaic unit conversions, the Fahrenheit is not appropriate per MOS:CONVERSIONS. I think the existing Fahrenheit conversion in the lead should be removed so it is consistent with the remainder of the article.—RJH (talk) 16:34, 19 May 2009 (UTC)

Can you make "regolith" a link - I had to copy and paste to get there - no trouble but it makes it easier and encorages research. Jay: UK —Preceding unsigned comment added by (talk) 12:02, 24 July 2009 (UTC)

Wrong URL on cite

If you look at the URLs in what are now references 38 and 103, you will see that they are the same. Therefore at least one of them is obviously wrong. The first one is correct: the URL is for that paper by L.V. Ksanfomality. The correct URL for the other paper, by G. Colombo, is

I cannot fix this because the article is semi-protected; would someone else please do so? -- (talk) 07:12, 30 May 2009 (UTC)

I fixed the incorrect DOI on the second source and added in an extra link for good measure. Thank you for identifying this issue.—RJH (talk) 18:14, 30 May 2009 (UTC)

Please, please change the wrong values !!

It is realy sad if even the original source provides false data !!!

I dont know how the NASA got these wrong numbers ??? but if somebody would correct them.

I am too busy right now.

They following comparison is 100% wrong.

Mercurys surface isnt around .108 that of our planet !!

The surface of about 74 mio km^2 is correct but this is one 74 mio/ 510 mio (earth surface) .1451 earth not .108 ???

Dont know who NASA got this value.

I didnt check the other values but maybe they are wrong as well. —Preceding unsigned comment added by (talk) 23:32, 27 May 2009 (UTC)

Mistakes happen. I have corrected the info. This is why investigators always try to verify numbers. This is just a simple division error. Do you know how spacecraft crash into Mars? Europeans use the metric system and then americans use the english system, if they don't convert ... Boom! -- Kheider (talk) 17:47, 28 May 2009 (UTC)

Yes conversion error could be the case, but also the volume is strangely wrong i think. if the radius-ratio is correct one only has to calculate the 3 power of the radius-ratio and one has the volume-ratio. Interessting this value is also wrong about 4,5% ?? I would assume that both mercury and earth are almost perfect spheres so you can simple use this "trick" —Preceding unsigned comment added by (talk) 22:58, 28 May 2009 (UTC)

I will probably give this one to NASA since planets are not perfect spheres. No number is going to be perfect. -- Kheider (talk) 23:20, 28 May 2009 (UTC)
There's a table of flattening ratios on the equatorial bulge article, although Mercury is not included. Earth's is less than a percent and I'd imagine Mercury is of the same order, so if you only use two significant figures it is probably okay.—RJH (talk) 19:33, 18 August 2009 (UTC)
The IAU specified the flattening of Mercury, Venus, Mars and Pluto as zero in 1976, thus spherical. The flattening for Mars changed when satellites orbited it. Several flattening ratios can be found in the literature for Mars, including that implied by Seidelmann 2007. Even though Venus was orbited by the Magellan spacecraft in the early 1990s, the IAU still (as of 2007) specifies its flattening as zero. Thus more precise measurements do not necessarily change the flattening. Similarly, the IAU still specifies that the flattening of Mercury is zero. The Messenger spacecraft may or may not find some non-spherical flattening. Both Venus and Mercury being spherical is consistent with their extremely slow rotation rates, in contrast to the much more rapid rotation rates of the other planets.
I question the maximum flattening specified in the Wikipedia articles for Mercury (<0.0006) and Venus (<0.0002) calculated by Deuar "from data in ref name=Seidelmann2007". Neither is supported by Seidelmann 2007, which specifically states that each planet's equatorial and polar radii are the same.
Using the volume of a sphere, (4/3)πr³, and the IAU mean radii for Mercury (2439.7 km) and Earth (6371.0 km), their volumetric ratio is 0.056155. This does indeed differ from the ratio in the article, 0.054, by about 4%. Some old radii may have caused the error. The ratio is still 0.056155 when the volume of an ellipsoid, (4/3)πa²c, and the IAU values for Earth's equatorial radius a=6378.14 km and polar radius c=6356.75 km in Seidelmann 2007 are used. — Joe Kress (talk) 02:54, 19 August 2009 (UTC)
The source of the erroneous 0.054 figure is [9]. When the volume for Mercury in km³ given on that page is divided by the volume for Earth given on the companion page [10], , the result is the same value derived above, 0.056155. This implies that 0.054 is the result a computational error, as was the 0.108 figure for the areal ratio. — Joe Kress (talk) 05:14, 20 August 2009 (UTC)

In the article "Geology of Mercury" it's written that "the Sun's tides on Mercury are about 17% stronger than the Moon’s on Earth", whereas in this one it's written that "the Sun’s tides on Mercury are about 17 times stronger than the Moon’s on Earth". I don't know which is the right value, and I can't check it. Can anyone do it? —Preceding unsigned comment added by (talk) 15:08, 28 October 2009 (UTC)

  1. ^ The Greek word Ἑωσφόρος (Heosphoros), meaning "Dawn-Bringer", which is also used as a name for the Morning Star, is not found in the New Testament.