Talk:Andromeda Galaxy

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Good article Andromeda Galaxy has been listed as one of the Natural sciences good articles under the good article criteria. If you can improve it further, please do so. If it no longer meets these criteria, you can reassess it.
Article milestones
Date Process Result
June 8, 2006 Peer review Reviewed
June 15, 2006 Good article nominee Listed
July 12, 2009 Good article reassessment Kept
Current status: Good article
WikiProject Astronomy / Astronomical objects  (Rated GA-class, Top-importance)
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There is a "Error: No valid link was found at the end of line 22." error in the page. — Preceding unsigned comment added by (talk) 23:08, 7 May 2013 (UTC)

In Fiction[edit]

  • Star Trek: TOS, a alien empire comes to conquer this galaxy.

UFO Lore[edit]

  • Home of the Andromedan aliens, who have (allegedly) ordered all other aliens OFF of Earth and OUT of the Sol star system. (talk) 04:34, 9 July 2008 (UTC)
Can someone add these? I can't, since the article is protected. (talk) 04:35, 9 July 2008 (UTC)

Fictional information of this nature can be added to Galaxies in fiction, which is linked from the "See also" section.—RJH (talk) 17:59, 11 July 2008 (UTC)

Different magnitude[edit]

The apparent magnitude of the Andromeda Galaxy is given as 3.4 and 4.4. The latter seems to be correct. —Preceding unsigned comment added by (talk) 10:13, 6 September 2008 (UTC) The magnitude is still given as 3.4, 3.44 and 4.36. The 4.36 is in note b. — Preceding unsigned comment added by (talk) 12:07, 13 July 2011 (UTC)

we should talk about how this galaxy will collide with the milky way[edit]

in the opening paragraph. Fourtyearswhat (talk) 19:36, 19 September 2008 (UTC)

Well, because that would mean the end of the milky way galaxy.--Jakezing (talk) 02:12, 7 November 2008 (UTC)

It'll be the end of Andromeda Galaxy, as Milky Way will swallow Andromeda Galaxy, Milky Way is about 40% larger than Andromeda Galaxy...THIS IS WRONG

  —Preceding unsigned comment added by (talk) 01:35, 15 April 2009 (UTC) 
Per WP:LEAD, the lead section is intended as a summary of the main article. The body contains a paragraph on the topic, so I think it deserves at most a sentence in the lead. Most of the material on the subject is now on the Andromeda-Milky Way collision article.—RJH (talk) 16:06, 7 November 2008 (UTC)

In the context of the Big Bang theory, why would another galaxy be approaching our Milky Way galaxy at one-thousandth the speed of light, 300 km/sec.? Larry R. Holmgren (talk) 19:36, 29 February 2012 (UTC)

Another inconsistency: If the Andromeda galaxy is approaching us at 300 km/sec (i.e. 0.001 c), then assuming it didn't accelerate as it gets closer, which it will) this gives an upper bound on the time to collision of 1000 x the current distance separating our galaxies in light years, which is quoted in the intro paragraph at 2.5 million light years, i.e. 2.5 billion years to collision. The number quoted in the second paragraph says this collision will occur in 3.75 billion years. This value is clearly way too high. I've seen all sorts of numbers for this time to collision quoted, but not a single calculation. All of this is readdressed in the last section which quotes an approach speed of only 100-140 km/sec vice 300 km/sec quoted previously. This value range makes the previous time to collision more reasonable, however this section pulls another time to collision value (450 billion years) out of the air which is inconsistent with the previous value. It would be nice to make all of these numbers more consistent with each other. — Preceding unsigned comment added by (talk) 18:03, 26 November 2012 (UTC)

Closest galaxy?[edit]

I've always thought that andromeda was the closest galaxy to our own, but the intro implies that it is merely the closest spiral galaxy to ours. Can someone verify this? Thanks! M00npirate (talk) 01:31, 16 December 2008 (UTC)

The Magellanic Clouds, for example, are much closer. See Local Group.—RJH (talk) 20:59, 16 December 2008 (UTC)
It's the closest galaxy to ours that is of a comparable size to ours, there are plenty of smaller ones nearer. --Tango (talk) 21:01, 16 December 2008 (UTC)

The Andromeda Galaxy is the nearest galaxy that is not a Dwarf Galaxy. Of course the Large Magellanic Cloud and the Small Magellanic Cloud are closer, But they are dwarf galaxies.--Anderson I'm Willing To Help 21:53, 21 July 2013 (UTC)

Some editor is not only misinformed about Hipparcos results, but believes EVERYONE ELSE is misinformed[edit]

Article currently states that Hipparcos either did not measure Cepheid variable-star distances with reasonable accuracy- or did not measure ANY CEPHEIDS AT ALL. Several dozen Cepheids fell within HIpparcos' effective range of ~100 parsec (a few hundred light years). Of those, a dozen or so were quite close, measured with strong S/N multiple times.

One possibility is that some editor is so grossly ignorant of distance measurement that she believes Hipparcos must measure Cepheids located inside Andromeda. This is, frankly, a shocking degree of misinformation. A quick read of the Hipparcos or Cepheid articles will illustrate the measurement method, but I'll summarize just to be thorough. Hipparcos CALIBRATES Cepheid distances; Andromeda Cepheids can then be observed with HST, Keck I/II, Gemini N, etc. —Preceding unsigned comment added by (talk) 00:03, 7 June 2009 (UTC)

I've removed both the uncited mention of 2.9 million light years and the dubious tagged stuff. 84user (talk) 11:26, 11 June 2009 (UTC)

Good article review[edit]

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

GA Reassessment[edit]

This discussion is transcluded from Talk:Andromeda Galaxy/GA1. The edit link for this section can be used to add comments to the reassessment.

GA review – see WP:WIAGA for criteria

This review is part of Wikipedia:WikiProject Good articles/Project quality task force/Sweeps, a project devoted to re-reviewing Good Articles listed before August 26, 2007.
  1. Is it reasonably well written?
    A. Prose quality:
    "The nucleus is double," poor wording. "It also should be noted that the galaxy" redundant phrasing. The article is good in most areas, but there are some parts that need work.
    B. MoS compliance:
  2. Is it factually accurate and verifiable?
    A. References to sources:
    B. Citation of reliable sources where necessary:
    While parts of the article maintain a high number of references, there are many uncited statements, and the whole table at the bottom is unreferenced. There is one {{citation needed}} tag, and I could add more.
    C. No original research:
    Uncited statements may contain original research.
  3. Is it broad in its coverage?
    A. Major aspects:
    B. Focused:
  4. Is it neutral?
    Fair representation without bias:
  5. Is it stable?
    No edit wars, etc:
  6. Does it contain images to illustrate the topic?
    A. Images are copyright tagged, and non-free images have fair use rationales:
    B. Images are provided where possible and appropriate, with suitable captions:
    Images are great, very informative and high quality.
  7. Overall:
    Pass or Fail:
    References are a big issue, this article must maintain a solid base of references to keep GA status. Article will be placed on hold until issues can be addressed. If an editor does not express interest in addressing these issues within seven days, the article will be delisted and reassessed as B-class. --ErgoSumtalktrib 22:03, 7 July 2009 (UTC)

I addressed the main concerns regarding citations, though part of that included removing the table, as I can see no reason for an arbitrary portion of the table on the main page about Andromeda's satellites to have been copied on to the page for Andromeda. I'll try to address the issue of citations there anyway, but I think the main concerns you raised for the article as it stands have been addressed. James McBride (talk) 09:28, 12 July 2009 (UTC)

I will have to give it one more review to spot any further problems, but it looks much better. Give me some time to make another assessment and I will let you know. --ErgoSumtalktrib 15:46, 12 July 2009 (UTC)
I believe there is one more statement that needs a ref. Other than that, all other issues have been addressed. --ErgoSumtalktrib 18:03, 12 July 2009 (UTC)
Okay, done. James McBride (talk) 21:44, 12 July 2009 (UTC)
Nice work. All issues have been addressed, article will be kept. --ErgoSumtalktrib 21:49, 12 July 2009 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

22:03, 7 July 2009 (UTC)

Name of the object in this article[edit]

I can't back this up with any sources, but i learned that this object was origanlly named "great nebula in andromeda" and later "galaxy in andromeda". Also, it is the constellation in which this object is located that is named after the princess in greek mythology, not the object discussed here itself. maybe i'm wrong here, but i think it should at least be looked into. (talk) 04:28, 1 January 2010 (UTC)

I would also like to propose that naming of the object in question be kept consistent throughout the article, unless it is important in a given instance that it varies. Either M31 or Andromeda but having both is mildly confusing until you realize what's going on Dwarfyperson (talk) 08:01, 14 January 2012 (UTC)

My understanding is that the name of the object is M31 or NGC224; an adequate (but not technically unambiguous) description of it is "the [spiral] galaxy in Andromeda". "The Andromeda galaxy", although a name in common use, is not very good as a formal name as it's probably not the only galaxy in the Andromeda constellation (by position on the sky, not distance). "Andromeda" alone, again, is in common use amongst professionals and others where context is clear, but so informal as to be technically wrong. An analogy could be to call the Crab Nebula (correctly the Crab Nebula, M1, NGC 1952, or Taurus A) "the nebula in Taurus", "the Taurus nebula" or just "Taurus". (Those who disagree with this might like to quote the great nebula in Orion, which is named even in formal writing "the Orion nebula".) I don't know if the formal name is discussed in good sources. In the article, after brief mention in the introduction, I would speak of M31 throughout; use of "the galaxy in Andromeda" or "the Andromeda galaxy" isn't too bad, and I personally don't think it's excessively confusing to mix with M31; "Andromeda" by itself is just wrong. I simply state this for consideration of contributors, I don't intend to push this. Pol098 (talk) 22:55, 5 February 2012 (UTC)

Observation history[edit]

This is ofcourse a load of bs. It was there in the sky for everyone to see for 1.000.000's of years.. crediting its discovery to anyone is just plain nonsense. You cant credit anyone with discovering the atlantic ocean either.

This claim is false "The Roman poet Avienus wrote a tantalizing line about the chained constellation in the 4th century AD.[14] who described it as a "small cloud" in his Book of Fixed Stars." Avienus never said that, it was in fact Abd al-Rahman al-Sufi. Even if you click on the link of the book, it states that HE is the author and HE is the one quoted saying that. Check other sources as well. I will make the correct change. (Parmis17 (talk) 08:05, 14 November 2010 (UTC))

Actually the planet Uranus "was there in the sky for everyone to see" for millions of years too - it can sometimes be seen with the naked eye as a sixth-magnitude 'star', and we know it was observed sometimes (listed in 18th century observation logs and so on). That doesn't mean anyone did spot it as noteworthy before Herschel in 1781. You have to realize that the Greeks and Romans were much less interested in weak, fuzzy, cloud-like objects in the sky than some medieval and (especially) post-Kepler astronomers would be. The idea of the stars as lit points on a firmament globe, all at the same distance from earth and all eternal, gave no particualr place for nebulas and the like, they would just have been seen as odd and inconsequential scrap on the pureness of the sky. (talk) 05:08, 18 November 2012 (UTC)

Alternative lead picture:[edit]

New image

I just imported this excellent picture (bottom image on right) from Flickr, and wondered whether anyone objected to using it as the lead image in the article. It's of a higher resolution, has a wider field of view and is more aesthetically interesting than the one we're using at the moment. However, it includes h-alpha, so thought it would be sensible to propose the change here first in case there is consensus that the current version has more encyclopedic value. NotFromUtrecht (talk) 20:42, 10 January 2011 (UTC)

Go for it; I like it. -- cheers, Michael C. Price talk 08:47, 11 January 2011 (UTC)
Either is ok for me. Casliber (talk · contribs) 09:39, 11 January 2011 (UTC)
I vote for the lead being more like what is seen with a simple telescope.Cesiumfrog (talk) 06:05, 30 January 2011 (UTC)

I am just wondering why this image had not been flipped? it is showing Andromeda how it appears through an uncorrected Telescope. do we print pictures of people upside down when taken through a lens? no we correct them and print the image so it looks as it should to the human eye. you have over 100 pages linking to this image and if you look at the image below (above on the main page) on this page you will see you have 2 images of Andromeda, one corrected and the other not its traveling in 2 different directions, one will miss the milky way, then other will collide with it in 4.4 billion years. Samantha.pia (talk) 17:01, 11 April 2011 (UTC)

elegant distance measurement[edit]

In 1922 Ernst Öpik presented a very elegant and simple astrophysical method to estimate the distance of M31.

This line of the article is possibly plagiarised. More importantly, where can we find a description of this elegant and simple method (which supposedly was far more accurate than Hubble's and is still used)? Cesiumfrog (talk) 06:10, 30 January 2011 (UTC)

The argument can be found here - not difficult to find. And here: [1] I can't tell how good it is. Myrvin (talk) 08:19, 30 January 2011 (UTC)
Britannica says "In 1922 Öpik proved that the source of stellar energy was nuclear and heavily dependent upon temperature. At this time he also made an estimate of the distance of the Andromeda Nebula that was still valid a half century later." Myrvin (talk) 08:24, 30 January 2011 (UTC)

Rotational velocities must be wrong[edit]

(quote from the article): rotational velocity climbs to a peak of 225 kilometres per second (140 mi/s) at a radius of 1,300 light-years (82,000,000 AU), then descends to a minimum at 7,000 light-years (440,000,000 AU) where the rotation velocity may be as low as 50 kilometres per second (31 mi/s). (end quote)

If one calculates the accelleration at 1,300 lightyears which is needed for a roatational velocity of 225 km/s (4,11E-09 m/sec2) the mass wich would cause this is 9,34E+39 kilo~ If one calculates the acceleration this mass causes at 7,000 lightyears one gets 1,42E-10 m/sec.

If however one calculates the acceleration at 7,000 lightyears for a rotational velocity of 50 km/s this is only 3,77E-11 km/sec2, 25% of what it should be. Do we have negative dark matter here, or has someone messed up the data? I suspect the latter Velzen5 (talk) 11:25, 27 March 2011 (UTC)

I think your calculations are done using an assumption of spherical symmetry (using the shell theorem). The galaxy is actually disc shaped, which might change things. I don't think you can model the gravitational field of a disc as the gravitional field of a point mass of the same total mass, the way you can with a ball. That said, I think your calculation contains an error that means it understates the problem - you have neglected the mass that exists between 1,300 ly and 7000 ly. That extra mass should compensate for some of the extra distance, giving faster rotational speeds. --Tango (talk) 12:02, 27 March 2011 (UTC)
Velzen, have you looked into this at all: [2] ? Cesiumfrog (talk) 22:45, 27 March 2011 (UTC)

Active Nucleus[edit]

The gxy has an active galaxy nucleus (AGN - Y1O-TLA) per SIMBAD and per Quasars and Active Galactic Nuclei (13th Ed.) (Veron+ 2010) (at VizieR). More specifically it is a "LINER-type Active Galaxy Nucleus" (or whatever) acc2 SIMBAD. FYI. Rursus dixit. (mbork3!) 13:34, 4 April 2011 (UTC)

Are there aliens in the Andromeda Galaxy?[edit]

Are there extra-terrestrial lifeforms, more specifically intellegent lifeforms in the Andromeda Galaxy? — Preceding unsigned comment added by (talk) 01:59, 16 July 2011 (UTC)

Well, given that there are an estimated trillion (that is, 1,000,000,000,000) stars in it, a reasonable answer would have to be "almost certainly". But now comes the hard part. If you can find indisputable evidence of even one of them, well, your first Nobel Prize would only be the beginning. Old_Wombat (talk) 10:16, 10 October 2011 (UTC)

Finding aliens in the Andromeda Galaxy would require finding maybe thousands of Extrasolar Planets that are not gas giants orbiting within a star's Habitable zone with earth-like conditions.--Anderson I'm Willing To Help 21:40, 22 July 2013 (UTC)
We have no idea whether there are aliens or not anywhere outside the solar system and some ppl claim it is "very likely" or "very unlikely", certainyl until we have proof this is NOT the article to be mentioning aliens in, fascinating a subject as it is. Thanks, ♫ SqueakBox talk contribs 21:30, 23 July 2013 (UTC)
Absolutely agree with Squeakbox's comments above. This is certainly not the article to be mentioning SETI searches. David J Johnson (talk) 21:36, 23 July 2013 (UTC)
I was not going to start a discussion on aliens, It was just an idea, mentioning how it might happen.--Anderson I'm Willing To Help 22:15, 3 August 2013 (UTC)
Then don't start a thread then! David J Johnson (talk) 22:35, 3 August 2013 (UTC)
The only thing we can be sure of is that aliens are no more or less likely in the Andromeda Galaxy than anywhere else, which is why this is not the article to mention or even discuss the possibility of aliens. Thanks, ♫ SqueakBox talk contribs 00:55, 4 August 2013 (UTC)
We can't really be sure of that either. Might be more or less likely, because the size of the galactic habitable zone could be different. — Reatlas (talk) 03:47, 4 August 2013 (UTC)
I'm going to disengage from this discussion, because i'm trying to gain positive notice. The article to maybe discuss this on is Search for Extraterrestrial Intelligence.Anderson I'm Willing To Help 08:32, 4 August 2013 (UTC)

Future Collision[edit]

Isn't the future collision also called into doubt by the accelerating universe observations? If I understand the margin of error on the measurements is such that Andromeda Galaxy might never collide, and instead be the last galaxy to disappear from our view.Bill C. Riemers (talk) 14:25, 12 December 2011 (UTC)

Another point of interest. In the advent of a collision what would be the effect of the gamma ray bursts from the Andromeda Galaxy super massive black holes, as the Andromeda Galaxy passed through the Milky Way Galaxy?Bill C. Riemers (talk) 14:25, 12 December 2011 (UTC)

Generally speaking, cosmological effects like the expansion of the universe don't have a significant effect on gravitationally bound systems, like galactic clusters. The Big Rip theory does end up with even gravitationally bound systems being ripped apart, but I think even the fastest acceleration consistent with our observations would mean the big rip happens a long time after the collision. I don't think there is any particularly reason to the collision to cause gamma-ray bursts. The combined galaxy will be larger, so there will be more bursts in it simply due to there being more stars, but that's all. --Tango (talk) 15:22, 13 December 2011 (UTC)

Can someone add the latest information about this future collision? See NASA's Hubble Shows Milky Way is Destined for Head-on Collision with Andromeda Galaxy. Also M33 seems to be involved in the collision. (talk) 20:58, 31 May 2012 (UTC)

You'll need to find a better article than that. It starts off saying the collision is certain and then quotes someone as saying the results are "statistically consistent" with a collision. "Statistically consistent" just means the probability of a collision is greater than 5%. --Tango (talk) 23:15, 31 May 2012 (UTC)
This is the relevant paper: The M31 Velocity Vector. III. Future Milky Way-M31-M33 Orbital Evolution, Merging, and Fate of the Sun. James McBride (talk) 16:53, 1 June 2012 (UTC)

Claim Isaac Roberts mistaking Andromeda for a "solar system"[edit]

The following uncited claim needs clarification: "[Isaac] Roberts mistakenly believed that M31 and similar spiral nebulae were actually solar systems being formed, with the satellites nascent planets" This is not stated in either the Isaac Roberts article or in the articles on the history of exoplanets or the correct terminology - planetary system. The only reference I can find is in a student publication "In 1888, he obtained a photograph of the Andromeda Nebula M31, well showing its spiral structure. Roberts believed that M31 and other spiral "nebulae" were solar systems in formation, with the satellite galaxies M32 and M110 being planets in formation", however there are no inline citations and the references listed appear not to support this. I really think this claim needs to be substantiated or removed from the article. --EvenGreenerFish (talk) 23:33, 2 April 2012 (UTC)

Lighter than the Milky Way?[edit]

As the Andromeda Galaxy is larger than the Milky Way and contains many times more stars, how can it be lighter? --KnightMove (talk) 10:25, 12 July 2012 (UTC)

Even if a galaxy does contain more stars then the Milky Way, It can be lighter. It all comes down to Density. Some galaxies are more dense, While others are lighter. Eliptical Galaxies are some of the most dense galaxies in the observable universe.--Anderson I'm Willing To Help 22:23, 18 July 2013 (UTC)
In addition, stars are not the only matter that exists. We also have free gas and dust, which contribute much more of a galaxy's mass than stars. We also have dark matter, which makes up the majority of the mass in the universe, and of which the Andromeda Galaxy has surprisingly little. StringTheory11 (t • c) 04:12, 20 July 2013 (UTC)
Thank you very much. But then it would be interesting whether this lesser weight is only attributed to dark matter, or also to 'classical' baryonic matter.
There have been changes in the article, and as of now, Andromeda Galaxy and Milky Way are rather inconsistent about the weight and the mass ranking of the two galaxies. --KnightMove (talk) 06:11, 21 July 2013 (UTC)

Andromeda's apparent magnitude[edit]

I've found in other sources like this paper or M31's entry on HyperLeda different apparent magnitudes for this galaxy. Would be wise to include them?. U-95 (talk) 00:38, 29 July 2012 (UTC)

Hole in the Andromeda Galaxy and date.[edit]

I know you mentioned "consumed by M31 in the past" But also please mention the date which was 200 mya. Also why didn't you mention the evidence for the collision with M32, the hole picked up by infra rays. — Preceding unsigned comment added by Anastronomer (talkcontribs) 06:23, 20 October 2012 (UTC)


I aplogize, I didn't realize that you put the date. — Preceding unsigned comment added by Anastronomer (talkcontribs) 19:50, 20 October 2012 (UTC)

Hubble vs Opik[edit]

Hubble's distance measure was 275 kpc, Opik's 450kpc. The Actual distance is around 800kpc. Given this, how is it that Hubble 'settled the debate'? — Preceding unsigned comment added by (talk) 12:32, 3 May 2013 (UTC)

Blueshift speed[edit]

The blueshift speed may need to be updated to 300 KM/Second Per search results at The NED galaxy database. I would like to gain consensus before i make the edit. Here is the reference for further examination. To prevent confusion, The Andromeda Galaxy is also known as Messier 31 (M31).--Anderson I'm Willing To Help 21:11, 16 July 2013 (UTC)

Oppose First off, I know nothing about astronomy. My opinion was sought out on whether or not to change this velocity to 300 KM/Second vs the currently listed 301, and my research of the NED sources uncover this as a reference along with the disclaimer:
"This information is indicative only. With the exception of the redshift they are unreferenced and highly inhomogeneous as to their origin. The Radial Velocity (when available) is computed from the listed redshift. The remaining values are designed to orient the user with a quick-look, overall assessment of the general properties of the object in question. ... This information is indicative only. With the exception of the redshift they are unreferenced and highly inhomogeneous as to their origin. The Radial Velocity (when available) is computed from the listed redshift." (your listed source)
It appears as though the currently cited source from 2006 is both more recent and more accurate from my (non-professional) assessment. --Jackson Peebles (talk) 03:26, 17 July 2013 (UTC)

Pictogram voting comment.svg Comment it is currently described in the article that the galaxy itself is currently on a blueshift, However, the blueshift velocity is not sourced, or, contains a dead source.Anderson I'm Willing To Help 03:44, 17 July 2013 (UTC)

I might leave this discussion to people (like me, due to being a member of the Southland Astronomical Society because i have excellent knowledge in the field of astronomy) who have excellent knowledge on astronomy and the subject.--Anderson I'm Willing To Help 03:47, 17 July 2013 (UTC)
Fair enough, Anderson - no harm intended. I am, as stated, by no means an expert. When determining consensus, feel free to disregard my comments in lieu of those with greater expertise. At this point, since I see no objections from others, so long as you cite your source, you should be in the clear to be bold and implement the change. --Jackson Peebles (talk) 22:45, 17 July 2013 (UTC)

YesY Info has been cited. Reference has also been fixed. Cheers,--Anderson I'm Willing To Help 21:19, 18 July 2013 (UTC)


Andromeda Galaxy /ænˈdrɒmɨdə/ is incorrect in American English. The vowel in the second syllable should be the low a (not the rounded a in British English). What is the general Wikipedia policy towards these two dialects? Give both? — Preceding unsigned comment added by (talk) 19:40, 20 April 2014 (UTC)

Please be more specific. In most of N. America (especially Canada), "father" and "bother" rhyme, as in "cot", and the "o" in Andromeda has that sound. Not everyone knows the jargon..."low", "rounded", etc. I think I agree with you, assuming I am guessing your meaning correctly. — Preceding unsigned comment added by (talk) 22:29, 20 September 2014 (UTC)

>== imposible ==

it is wrong to say that the universe is only 13.8 billion years old if it is true then the speed of light is not constant or was there ever a big bang its all wrong — Preceding unsigned comment added by [[Special:Contributions/([[User talk:|talk]]) 12:36, 26 October 2014 (UTC)


it is wrong to say that the universe is only 13.8 billion years old if it is true then the speed of light is not constant or was there ever a big bang its all wrong — Preceding unsigned comment added by Sabbathart (talkcontribs) 12:59, 26 October 2014 (UTC)

You should probably answer this first.   ~ Tom.Reding (talk|contribs|dgaf) 18:56, 16 December 2014 (UTC)

Request for semi-protection[edit]

From Wikipedia:Rough guide to semi-protection, most of the IP edits this year have been reverted, unreverted IP edits have been minor, reversions are from a wide range of IPs, the traffic seems to be increasing lately, and the majority of the contributions are from registered users. Seems like an easy decision to me, except that I don't know whether the vandalism frequency is high enough to warrant semi-protection. I'll leave that to the admins.   ~ Tom.Reding (talk|contribs|dgaf) 16:02, 16 December 2014 (UTC)

Today I've been reverting several vandal attacks. What's going on? Are the kids in winter vacation? Tetra quark (talk) 19:47, 16 December 2014 (UTC)
Finally got around to finding out how & where to make a formal request: Wikipedia:Requests for page protection#Andromeda Galaxy. Thanks for the recent vandalism reversion, Isambard Kingdom.   ~ Tom.Reding (talkcontribsdgaf)  23:39, 23 March 2015 (UTC)


The infobox at the beginning of the article says that the diameter of the galaxy is ~220 kly, whereas the "recent distance estimate" contains a calculation that indicates a diameter of 141 +/- 3 kly. What is the current best estimate for the diameter according to scientific consensus or official bodies? Could someone edit the article to be internally consistent? Ketone16 (talk) 22:12, 8 January 2015 (UTC)

The diameter of galaxies is always a thing that causes contradictions, so it is always risky to mention their size. If you choose some other galaxy and google its diameter, there will be several different websites stating wildly different values. In my opinion there are two reasons for that. 1, the size of galaxies really aren't known for sure and 2, it is not that simple to determine where the edge of a galaxy is. The Pinwheel Galaxy is an example. This [3] picture is the galaxy in visible light, and this one [4] is the same galaxy in different wavelenghts. You can see it gets harder to determine the edge.
In my opinion we should leave the diameter of the Andromeda galaxy as being 220kly. The other value in the article seems to have been found by original research, as the note next to it suggests Tetra quark (talk) 22:57, 8 January 2015 (UTC)
Thank you. I am not sure, however, that your recent edit to change the 141 kly figure to 220 kly is correct given the context of that paragraph. The whole paragraph originally stated that the average of the new distance measurements is 2.54 +/- 0.11 Mly, and that based on that distance the diameter of the galaxy is 141 +/- 3 kly and subtends 3.18°. All of these numbers are related to each other in the original research calculation. If you merely change the 141 to 220, then the statement that the 220 Mly diameter is based on the average distance measurement of 2.54 +/- 0.11 Mly is wrong, plus the +/- 3 kly uncertainty for the diameter is wrong, and the 3.18° figure is definitely wrong (I checked and that figure is consistent with a distance of 2.54 Mly and a diameter of 141 kly, assuming that we are viewing the galaxy perpendicular to the plane of its spiral). My inclination would just be to delete the whole final paragraph of that section, which is about new distance estimates and shouldn't contain original research on diameters anyway. Ketone16 (talk) 13:58, 11 January 2015 (UTC)
Also, I may have missed something obvious, but I just looked up the cited reference for the ~220 kly diameter figure and wasn't able to find that figure (or the 67,450 +/- 920 kpc figure that it seems to be based on) in the reference. I am still left with the question of what is the best source to use for the diameter of M31. Ketone16 (talk) 14:00, 11 January 2015 (UTC)

Nasa has just released the largest image ever made of the Andromeda Galaxy[edit]

Should this image be mentioned in the article? [5]dv82matt

- I added an external link to: A National Geographic video explaining the NASA image Hubble's image of the Andromeda Galaxy mentioned in the item above. Jcardazzi (talk) 12:55, 21 March 2015 (UTC)jcardazzi