Talk:Polaris

From Wikipedia, the free encyclopedia
Jump to: navigation, search
WikiProject Astronomy / Astronomical objects  (Rated C-class, High-importance)
WikiProject icon Polaris is within the scope of WikiProject Astronomy, which collaborates on articles related to Astronomy on Wikipedia.
C-Class article C  This article has been rated as C-Class on the project's quality scale.
 High  This article has been rated as High-importance on the project's importance scale.
Taskforce icon
This article is supported by WikiProject Astronomical objects, which collaborates on articles related to astronomical objects.
 

Figure[edit]

--67.133.79.98 14:46, 27 October 2006 (UTC)The figure for the semimajor axis of the companion, given as 5 AU, is obviously in error. Here's why: a = cuberoot of the total mass times the period squared (say, 30 years). For any reasonable value of M (which can hardly be less than 10 times our sun's, given the luminosity of Polaris A), the size of the orbit comes out at about the distance of Pluto from the sun--not Jupiter!--for having extra mass in the system, causes them to revolve FASTER. The best approximation[18] was made using the leading edge of the constellation Ursa Major as a point of reference. The leading edge (consisting of the star Dubhe) is referenced to a clock face and the azimuth of Polaris worked out for different latitudes. Addendum. When i wrote the foregoing, i didn't have precise figures for Polaris's mass. By the Cepheid relation M = .58 + .24 log P (in days) the mass of the primary should be about 5.29 times the Sun (not 8 to 10, which is more typical of a F-type supergiant of this luminosity). Assuming for the moment that the unseen companion is about 300 times dimmer than the visible primary, this comes out to a mass ratio of about Ma/Ma+Mb of 0.75; & the semimajor axis is 18.35 Astronomical Units (or 18.7, if you use Burnham's period of 30.5 years)...more like the distance of Neptune. (Its eccentricity takes the two stars from 7 to 29 AU separation.) The displacement of the primary amounts to about 4.58 AU, or 426 million miles, presumably the source of the quoted figures (with 290 million miles, given by Burnham, the mass of the companion becomes very small indeed). But this is a small portion of the entire orbit.

This is a good subject for calculating derived figures on, for the values derived from Cepheid equations can be tallied with the observed type F3 main sequence third star; thus the range of distances possible is fairly narrow, in comparison with many other supergiant stars, e.g. Canopus or Rigel.

Exterior Cosmology[edit]

Is is known yet whether the Earth rotates in a Galactic or Exterior Object cosmology? That can be boiled down to whether the Earth's axis is stable in relation to the Milky Way Galaxy or to the exterior galaxies such as Andromeda and the zillions of others.

SyntheticET (talk) 17:45, 17 November 2007 (UTC)


Dominance of the North?[edit]

I once read that a major factor contributing to the dominance of the northern hemisphere in such activities as ocean navigation and widespread colonization and travel was due to the fact that there is a North Star, but no South Star. Has anyone else heard this? --Golbez 21:31, Sep 27, 2004 (UTC)

Nope I haven't seen that one, but see also Guns, Germs, and Steel. — RJH 20:01, 17 January 2006 (UTC)

I could figure out the point in the sky thats south based on the constellations in one night of looking up there. Ancient people have figured out things a lot more complicated than that.

It is definitely nothing to do with the pole star - it's quite simple there is far more land and resources in the Northern hemisphere and so there have always been far more people in the Northern hemisphere. In any case, around the time of Christ there was no bright star within 5° of the pole whereas Miaplacidus was quite close to the South pole --AssegaiAli 18:05, 9 October 2007 (UTC)

Join this article?[edit]

This article is of the same subject as North star, and Pole star. i think it would be good to join these articles.

above by 12:54, user:Gxojo at 12:54, 28 Jan 2005
  • No, North Star is not about Alpha Ursae Minoris per se. It is about all North Stars, such as will be Vega in the future. And pole star covers both North Star and South Star (or should). Polaris, inappropriately named, covers only Alpha Ursae Minoris. 132.205.15.43 04:00, 1 Feb 2005 (UTC)


Visibility from the Southern Hemisphere[edit]

Polaris can be visible from locations near the equator in the southern hemisphere. Polaris is about 0.75° from true north. At an elevation of 3km, horizon dip is 1.75°, and atmospheric refraction can be good for another 0.5°, depending on conditions. Adding these up, Polaris can rise over the horizon at locations as far as 3°S.

At 3km elevation, atmospheric extinction at 3° from the horizon can be as low as 2 magnitudes, and as low as 5 magnitudes at the horizon itself. Under these near perfect circumstances, Polaris could be a naked eye magnitude 4 at (or just south of) the equator, and up to magnitude 7 at 3°S. james and Christian wuz herez — Preceding unsigned comment added by 38.117.102.236 (talk) 12:24, 18 April 2012 (UTC)

Distance from the north pole[edit]

Shouldn't it be 42', not 42" ? Or what exactly does " mean (compare the coordinates)? Otoomet 16:45, 2 July 2006 (UTC)

Oops, that's embarrassing. I actually wrongified that part of the article months ago. The HTML should have read ′ instead of ″. I've fixed it. -- Xerxes 20:58, 2 July 2006 (UTC)

If the declination is 89° 15′ 51″ (as stated in the table under the figure), then shouldn't the distance from the north pole be 90° - ( 89° 15′ 51″ ), i.e. just over 44' and not 42' as stated in the article? What am I missing? Jbuddenh (talk) 17:02, 28 May 2008 (UTC)


'It is very close to the north celestial pole (42′ away as of 2006)'. . .'At present, Polaris is 0.7° away from the pole of rotation (1.4 times the Moon disc)'.

1.4 times the moon's diameter is a HUGE optical distance, I never realised it was that far out - I don't think that this can be called 'very close' at all - I had always assumed that it was identical for all practical purposes, as I think most people do - this is very important and ought to be emphasised - at the very least changed to 'about one and a half moon diameters from the north celestial pole'.

81.100.161.66 (talk) 22:17, 6 October 2009 (UTC)


Polaris Ab[edit]

This 10 Jan 2006 news release contained material an amateur like me would be interested to read in the article:

  • "The companion proved to be less than two-tenths of an arcsecond from Polaris — an incredibly tiny angle equivalent to the apparent diameter of a quarter located 19 miles away."
  • By watching the companion star in its 30-year orbit, astronomers expect to learn not only the stars' orbits but also their masses, valuable because it is the nearest Cepheid variable, the brightness variations of which are used to measure the distances of galaxies and the expansion rate of the universe.

--Wetman 06:10, 18 October 2006 (UTC)

General complaints[edit]

"Rust in Peace...Polaris". Is a reference to the nuclear missile system, and nothing to do with the star apart from the missile system beign named after it, which is just daft.

From the linked article on the album:-

"I was driving home from Elsanon... um, Lake Elsanon. I was tailgating somebody, racing down the freeway, and I saw this bumper
 sticker on their car and it said... you know, this tongue in cheek stuff like, 'One nuclear bomb could ruin your whole day,' and
 then I looked on the other side and it said, 'May all your nuclear weapons rust in peace,' and I'm goin', ' 'Rust in Peace.' Damn,
 that's a good title.' And I'm thinkin' like, 'What do they mean, rust in peace?' I could just see it now - all these warheads
 sittin' there, stockpiled somewhere like Seal Beach, you know, all covered with rust 'n' stuff with kids out there spray-painting
 the stuff, you know." - Dave Mustaine, the band's main songwriter.

Obviously and from the horses mouth, nothing to do with the star. Perhaps the song should be linked in an article about bumper stickers?

As for "In the song, Polaris is the name of a disease." lyrics from the song:-
    "I am a nuclear murderer I am Polaris
     Ready to pounce at the touch of a button"

"Load Star" Load of BS. It was Lode only, until the bloody educational collapse of the late 20th century meant that no-one can spell anything anymore. Lodestone points to the lode star, a load of stone just sits there.

While I'm on it, the diameter of quarters is only a useful example to people in the US who regularly see quarters. 195.27.13.34 13:13, 8 June 2007 (UTC)

Star chart for North Pole[edit]

I suggest it would be useful to draw a diagram of the stars near celesial north pole, and trace a rough path of the pole over time. --206.75.168.235 05:15, 2 August 2007 (UTC) :( Actually, I'm Kevinkor2 (talk · contribs) but too lazy to log in. ):

Culture section[edit]

Does a list of bands really belong in an encyclopedia article about an astronomical object? Keeping in mind that Wikipedia is not a trivia collection, are there any reasons to keep it? Feezo (Talk) 19:08, 19 August 2007 (UTC)

More references[edit]

I think we need more references to eventually reach FA status with this article. RJFJR (talk) 16:59, 3 January 2008 (UTC)

Ptolemy?[edit]

I'm confused, the introduction says that Polaris was first noticed by William Herschel in the 18th century, but then refers to the star's rapid evolution from the time when Ptolemy first noticed it. Who noticed it first? —Preceding unsigned comment added by 83.28.18.214 (talk) 09:10, 8 February 2008 (UTC)

The introduction says "Polaris B" was first noticed by William Herschel, not that Polaris was first noticed by him. Ptolemy was certainly NOT the first to notice Polaris. It was certainly known to Hipparchus and no doubt to the Babylonian astronomers if not to the Sumerians at least 3 millennia before Ptolemy. However, at that time and even at the time of Christ, Polaris was NOT the closest star of similar magnitude to the Celestial north pole. Jbuddenh (talk) 17:32, 28 May 2008 (UTC)

I love the artist's impression[edit]

. . . but it's too YELLOW. A star that yellow would be a G5 or G8. The Polaris system would be stars of brilliant white with a trace of blue, like all F-types. (Bluish-yellow?) 68Kustom (talk) 11:51, 17 February 2008 (UTC)

Since when do F stars of any flavour have a hint of blue? And Polaris is a late F star, not much hotter than the sun. Hint of yellow perhaps, hint of blue definitely not. Lithopsian (talk) 16:36, 15 November 2012 (UTC)

Changing brightness?[edit]

this article says Polaris has been undergoing major unexplained changes in brightness over the years. Surely this is worth mentioning in the wiki article? http://www.physorg.com/news135871831.html vroman (talk) 18:20, 23 July 2008 (UTC)

I agree. Reference the research: [1] --Dupes (talk) 18:31, 25 July 2008 (UTC)

Relevance of Assyrian reference[edit]

Under "Pole star", there is " The antiquity of its use is attested by the fact that it is found represented on the earliest known Assyrian tablets. " I have two concerns about this statement. One, it's not referenced. Two, the earliest Assyrian tablets go back to c. 2000 BC (see the Assyria article). At this time, Polaris was nowhere near the North Pole, which was closer to Kochab or Thuban at that time. So the Assyrian reference is more likely to denote one of those two stars (if it refers to a pole star).

-Craig Heinke

Etymology?[edit]

etymology (n): An account of the origin and historical development of a word.

Nowhere in the "Etymology and cultural significance" section of this article is the etymology of the name "Polaris" discussed or mentioned. I found out more about the etymology of the name by looking in a dictionary. From wiktionary: From Latin Stella polaris, "pole star" --66.69.248.6 (talk) 19:12, 28 March 2009 (UTC)

It's probably my misunderstanding, but is this a contradiction?[edit]

In the Pole Star section, it says:

At present, Polaris is 0.7° away from the pole of rotation

But in the article, "North Star" it says:

In 2006 Polaris was 42' from the north celestial pole

I assume the north celestial pole and pole of rotation to be the same, correct?

Thus, what is the problem here? One article says 0.7°, the other says 42'? I am inclined to go with 42 due to what the North Star article said about progression of pole stars. If the last pole star was in place 5,000 years ago, and the next pole star will be in place in 1,000 years, it makes sense that it must currently be further away from the pole.

Can someone help? —Preceding unsigned comment added by Harleh (talkcontribs) 03:23, 8 May 2009 (UTC)

0.7° is the same as 42 arcmin. So what, indeed, is the problem? Skeptic2 (talk) 11:53, 8 May 2009 (UTC)

Mormon folklore[edit]

Given that there is some minor Mormon folklore regarding Polaris and an alleged statement by Joseph Smith, Jr., but this is presented as if this is actually believed by Latter-day Saints. The next statement in this article then stretches credibility to the limit, which uses a Sunstone Magazine comic as evidence of an actual belief that the Lost 10 Tribes would return in flying saucers! This is ridiculous! The comic (if it actually exists as described, which has not been verified because specifics on the edition & page it appeared in are missing from the cite) is extending & exaggerating a folk notion to reductio ad absurdum, not documenting or describing an actual belief. That bullet point needs some major rework, or should just be removed altogether. -- 208.81.184.4 (talk) 17:38, 2 July 2009 (UTC)

I was raised in the LDS Church and when I attended church in San Francisco in the 1950s, it was assumed by many that the Ten Lost Tribes went to Polaris (not to the northern parts of Earth) because of that statement by Joseph Smith and many people in church reasoned that the only way they could get back from Polaris was by flying saucers because in the 1950s everyone was talking about flying saucers (How else could they get back unless it was by either by using rocket ships or by teleportation?). Obviously it is not believed by all LDS people but it is believed by some and that is why the cartoon appeared in Sunstone Magazine. Even those who do believe it admit it is Mormon folklore and not official Mormon doctrine. Keraunos (talk) 01:35, 5 July 2009 (UTC)

"Yilduz" and Turkish[edit]

Yilduz is from the Turkish word for "star" (see Yildun).

I couldn't completely understand that part from the article, but the Turkish word for "star" is actually "yıldız". I think that part should be something like;
Yilduz is from the Turkish word "yıldız" for "star" (see Yildun).
to avoid misunderstandings.

However, I didn't want to edit it. If it is ok to edit it like this, don't wait for me to do it, and improve the section.
--ThoAppelsin (talk) 00:20, 15 August 2010 (UTC)

Due north twice a day[edit]

The article mentions that Polaris is due north twice a (sidereal) day (reminding me of the comment about a stopped clock), but that is true of every star, surely? I just don't think it is a useful statement, and I see it replicated in isolation in various other web pages lifted from WP. I realize it is here in the context of correction tables, but even then the statement would be "the correction is zero, twice a day", which I don't think would be a useful addition. Furthermore, the sentence beginning "the best approximation" seems little off; it might be better to say "traditionally, these tables have references Dubhe (etc)". Comments? David Brooks (talk) 19:24, 27 August 2010 (UTC)

Correction: "due north twice a day" is true of a subset of stars, dependent on latitude, I realize. David Brooks (talk) 16:25, 28 August 2010 (UTC)

Which one is the variable?[edit]

The article doesn't quite explicitly say which star is the Cepheid variable. I take it that α UMI A is the variable one? --Dylan Thurston (talk) 00:08, 11 October 2010 (UTC)

Of course α UMi A is the variable!


-Alexrybak (talk) 12:28, 26 May 2011 (UTC)

No "of course" about it. α UMi A is iself a spectroscopic binary. The primary is a supergiant Cepheid variable while the secondary is a main sequence star of approximately the same temperature but much lower luminosity, only a little brighter than the sun. The article completely fails to make this clear and there is great confusion between the various stars in the system, especially in the starbox. Lithopsian (talk) 17:46, 13 November 2012 (UTC)

Name[edit]

α UMi needs a name. I suppose we name it "alarsa" (al+ursa).

-Alexrybak (talk) 12:35, 26 May 2011 (UTC)

It's already got one: "Alruccabah" 220.255.1.60 (talk) 03:24, 3 July 2011 (UTC)

Confusing explanation?[edit]

The 'Role as a pole star' section of the article currently ends with:

"The best approximation[18] was made using the leading edge of the constellation Ursa Major
 as a point of reference. The leading edge (consisting of the star Dubhe) is referenced to
 a clock face and the azimuth of Polaris worked out for different latitudes.

How does an edge consist of a single star? What does "referencing to a clock face" require one to do? Moreover, reference 18 leads to an undocumented Excel spreadsheet which does not clarify the point.

Spectral type[edit]

In the overview of the spectral type F2 Polaris is mentioned, however in this article there is only a F3 star, but non F2. Can anyone check which statement is correct? — Preceding unsigned comment added by 62.217.41.124 (talk) 00:09, 3 October 2012 (UTC)

Polaris, being α UMi A, is a close binary. However the primary α UMi Aa contributes almost all the light and is spectral type F7Ib. The spectroscopic secondary α UMi Ab is difficult to examine clearly but is approximately F6V. A more distant companion α UMi B is visible optically and has been known for a long time. Recent work gives it a spectral type of F3V. I have found recent papers deriving updated data for all three of these stars and will update the article shortly. Lithopsian (talk) 00:08, 14 November 2012 (UTC)

That artists impression ...[edit]

... is highly misleading. Polaris B is considerably brighter than the closer companion Polaris Ab, around half a magnitude in the V band. Presumably the image is supposed to be taken from a close vantage point and hence Polaris B is much more distant than Polaris Ab but there is no way to know that from the image or the description. Hence anyone viewing the image will come away with the impression that the close companion is a lot more luminous than the distant one. Lithopsian (talk) 00:42, 14 November 2012 (UTC)

Starbox[edit]

I'm attempting to update the parameters for this star system, and want to clearly show things like spectral types, masses, etc. for three components: Aa, Ab, and B. The current starbox format does not seem up to the task. Would the starbox multi template work better? Or would that just lose me the orbital information? Lithopsian (talk) 16:32, 15 November 2012 (UTC)

Maybe. α UMi C and α UMi D should also get their information. --Artman40 (talk) 23:55, 30 November 2012 (UTC)
The starbox would be crazy wide :) I'm not aware of particularly good data for these components anyway, certainly not enough to fill a starbox. Here are the Simbad pages for C and D, pretty sparse: http://simbad.u-strasbg.fr/simbad/sim-id?Ident=%40317447&Name=CCDM%20J02319%2b8915C&submit=submit and http://simbad.u-strasbg.fr/simbad/sim-id?Ident=%40317446&Name=CCDM%20J02319%2b8915D&submit=submit Lithopsian (talk) 00:09, 1 December 2012 (UTC)
Maybe then something more like in Castor article? --Artman40 (talk) 05:27, 1 December 2012 (UTC)

Please review this[edit]

323 ly latest calculations.

Astronomers clash over the distance to the famed North Star

http://phys.org/news/2012-11-astronomers-clash-distance-famed-north.html — Preceding unsigned comment added by 109.242.59.163 (talk) 02:31, 4 December 2012 (UTC)

Anyone who wants to reference this result, please use the arXiv preprint reference that I've already created (name=turner), hopefully to be replaced by the peer-reviewed journal when it is released. Lithopsian (talk) 12:19, 5 December 2012 (UTC)
I'm never comfortable with papers that quote some relatively obscure or old results in support of their surprising new idea while ignoring recent and contradictory work. In this case, a method subject to a number of potential inaccuracies has been used to derive a distance that contradicts several different methods, some of which have a very low margin of error. For example, the Hipparcos parallax for such a close star ought to be highly accurate (even allowing for it being a supergiant star with companions), and results from studies of both the primary and companion have supported this distance. Remarkable claims require remarkable evidence and I don't see it yet. I'll scan some more papers and see if there is support for anything more than a brief comment about this distance calculation. Lithopsian (talk) 09:52, 4 December 2012 (UTC)
I've slightly expanded the comments added by fotaun, mentioning why this is such an important piece of data. Although I'm a big fan of referencing recent work with the best equipment and most advanced models, this latest distance estimate still makes me very uncomfortable. Going back many decades, distance estimates tended to be closer to 100 parsecs than 130. There are many papers finding a distance in the 100-110 parsec range over the last 10-20 years, although a remarkably large number of them are by the same author quoting previous work by the same author (clearly an expert with a focus on this type of star). I just have a tinge of fear that this is repeatedly calculating the same value from the same models despite direct evidence that the models need a little tweak. The latest Turner paper derives a distance 30% lower than the previous value (130pc from Evans et al, Hipparcos, etc) , apparently supported by the same data: the expected luminosity of Polaris B as an F3 main sequence star. At a guess I would suggest that treating Polaris B as a zero-age main sequence (ZAMS) star could account for the discrepancy, since Polaris B is clearly not a ZAMS star. F-type stars increase in luminosity by over 50% by the end of core hydrogen burning, and this corresponds to about a 25% difference in the calculated distance. Lithopsian (talk) 12:19, 5 December 2012 (UTC)
Thanks for your comments and working on this. Hopefully we can get some of your deeper understanding of this issue into the article. I added a new distance section to expound on this area. I look forward to your contributions! Fotaun (talk) 17:03, 5 December 2012 (UTC)

Relative apparent brightness[edit]

Many people mistakenly believe that the North Star is the brightest star in the night sky. This may be because it's the only star they've ever heard of, and so they assume it must be the brightest. Anyway, I wanted to clarify this, although I don't really have a reference for "people mistakenly believe it's the brightest star." So added a phrase to the introduction saying it's the 45th brightest star in the night sky. (Wikipedia's List of brightest stars has it at number 46, but that's because they include the Sun in that list.) —MiguelMunoz (talk) 23:28, 7 August 2014 (UTC)