Talk:Andromeda Galaxy/Archive 2

PROBLEM
There is a "Error: No valid link was found at the end of line 22." error in the page. — Preceding unsigned comment added by 65.9.224.15 (talk) 23:08, 7 May 2013 (UTC)

In Fiction

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

UFO Lore

 * Home of the Andromedan aliens, who have (allegedly) ordered all other aliens OFF of Earth and OUT of the Sol star system.


 * 65.173.105.27 (talk) 04:34, 9 July 2008 (UTC)


 * Can someone add these? I can't, since the article is protected.65.173.105.27 (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.&mdash;RJH (talk) 17:59, 11 July 2008 (UTC)

Some editor is not only misinformed about Hipparcos results, but believes EVERYONE ELSE is misinformed
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 12.176.210.201 (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
22:03, 7 July 2009 (UTC)

elegant distance measurement

 * 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. https://www.cfa.harvard.edu/~huchra/ay202/opik.pdf And here: 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
(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: ? Cesiumfrog (talk) 22:45, 27 March 2011 (UTC)

Active Nucleus
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. ( m bork3 !) 13:34, 4 April 2011 (UTC)

Alternative lead picture:


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)

Different magnitude
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 93.97.55.83 (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 93.97.194.200 (talk) 12:07, 13 July 2011 (UTC)

Claim Isaac Roberts mistaking Andromeda for a "solar system"
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 http://messier.seds.org/xtra/Bios/roberts.html "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)

Future Collision
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. 83.83.36.26 (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)

Andromeda's apparent magnitude
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.
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 (talk • contribs) 06:23, 20 October 2012 (UTC)

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

Observation history
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. 83.254.151.33 (talk) 05:08, 18 November 2012 (UTC)

we should talk about how this galaxy will collide with the milky way
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 88.109.209.213 (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.&mdash;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 74.96.159.30 (talk) 18:03, 26 November 2012 (UTC)

Hubble vs Opik
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 81.99.233.105 (talk) 12:32, 3 May 2013 (UTC)

Blueshift speed
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)

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)

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

Lighter than the Milky Way?
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)

Closest galaxy?
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.&mdash;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)

Are there aliens in the Andromeda Galaxy?
Are there extra-terrestrial lifeforms, more specifically intellegent lifeforms in the Andromeda Galaxy? — Preceding unsigned comment added by 68.189.186.199 (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)

Pronunciation
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 24.46.193.105 (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 184.147.124.193 (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 talk) 12:36, 26 October 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 Sabbathart (talk • contribs) 12:59, 26 October 2014 (UTC)


 * You should probably answer this first.  ~ Tom.Reding (talk&#124;contribs&#124;dgaf) 18:56, 16 December 2014 (UTC)

Diameter
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 picture is the galaxy in visible light, and this one  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
Should this image be mentioned in the article? —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. http://video.nationalgeographic.com/video/short-film-showcase/a-hundred-million-stars-in-3-minutes? Jcardazzi (talk) 12:55, 21 March 2015 (UTC)jcardazzi

Request for semi-protection
From 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&#124;contribs&#124;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: Requests for page protection. Thanks for the recent vandalism reversion, Isambard Kingdom.  ~ Tom.Reding (talk ⋅contribs ⋅dgaf)  23:39, 23 March 2015 (UTC)

Name of the object in this article
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.

92.116.36.115 (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)


 * Yes, Pol098 is absolutely right here. M31 is correct, although I also like the Great Andromeda Galaxy as a name. Andromeda Galaxy is ambiguous, even if in practice everyone will know which galaxy it refers to. TowardsTheLight (talk) 22:56, 12 June 2015 (UTC)

Amateur observing
Do you think is worth to add a section describing observations from an amateur POV (when and where she's better seen, what can be spotted with the naked eye/binoculars/etc)? --U-95 (talk) 22:19, 4 October 2016 (UTC)
 * Yes. A paragraph or so on this could be interesting to many readers. Isambard Kingdom (talk) 22:35, 4 October 2016 (UTC)

Error in Recent distance estimate Section
67,450 ± 920 pc makes no sense. It must be 67,450 ± 0,920 kpc

Jonorbe (talk) 16:53, 6 October 2016 (UTC)

External links modified
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M31 -> Andromeda
Can we change "M31" to "Andromeda" is most cases? Right now the article makes mixed use of these two designations, and for some readers this might be confusing. Isambard Kingdom (talk) 16:35, 9 October 2016 (UTC) ✅ Isambard Kingdom (talk) 18:58, 21 October 2016 (UTC)
 * I disagree. Andromeda is a constellation. M31 is the galaxy, so M31 is a more appropriate name or designation to use in this article. I'm a bit troubled with "Andromeda Galaxy" as well because there are very many galaxies in the constellation Andromeda. "Great Andromeda Galaxy" might be more suitable than "Andromeda Galaxy", but M31 is short and simple.TowardsTheLight (talk) 20:47, 21 October 2016 (UTC)
 * Okay, note that I waited for quite a while before going ahead with the change (got no input until now!). Of course the name of the article is "Andromeda Galaxy", not "M31". Also, while it is true that Andromeda is also the name of a constellation, I don't think any of the instances where "Andromeda" is used confuses the two. I checked this when making the change. Thanks. Isambard Kingdom (talk) 20:56, 21 October 2016 (UTC)
 * Apologies for not responding earlier: I didn't notice the original comment. "Messier 31" indeed redirects to this article with the title "Andromeda Galaxy". TowardsTheLight (talk) 21:56, 21 October 2016 (UTC)

Suggest adding an inspirational photo of the Andromeda Galaxy
Please consider adding the following "simulated" photo of the Andromeda Galaxy, which shows what it would look like in our sky if it were only much brighter. Imagine seeing that in the sky every night!

The image of Andromeda Galaxy: https://i.kinja-img.com/gawker-media/image/upload/s--paTMMEl_--/c_scale,fl_progressive,q_80,w_800/19bal4d1p8fncjpg.jpg

From the page: http://sploid.gizmodo.com/the-incredibly-huge-size-of-andromeda-1493036499

It might need verification from someone knowledgable in astronomy, but this photo is such a dreamy sight I think it would add a lot to the article for people to see what it would ACTUALLY LOOK LIKE if Andromeda were brighter. I like this photo better than any other rendition of the Andromeda Galaxy because of the combination of dark sky, angle of Andromeda, zoom level, and placement only somewhat near our moon.

This photo to me says:  our galaxy is not alone.

68.189.37.162 (talk) 21:36, 17 February 2017 (UTC)

External links modified
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1939 observations
As a point of historical reference (suggesting some discrepancy in the present article), in 1939 the distance to the 'Andromeda Nebula' was thought to be 210,000 parsecs (680,000 ly) 'from studies of Cepheid variables'. Cf Babcock, Lick Observatory Bulletin#498, 1939 In this article, Horace W. Babcock also observes that 'the nearly constant angular velocity of the outer parts of M31 is the opposite of the 'planetary' type of rotation believed to obtain in the outer parts of the galaxy' ... an early indication of 'dark matter'. Twang (talk) 23:30, 29 July 2017 (UTC)

Image that came through the Wiki Science Competition
Adding this picture here in case it's useful. It was uploaded by the photographer for the Wiki Science Competition in the United States (and was one of the finalists). &mdash; Rhododendrites  talk \\ 05:35, 26 January 2018 (UTC)

Adromeda size - revision
Just came across new research that adromeda is only 110,000 light-years across, roughly the same size as our own galaxy. This article should be revised. NocturnalDef (talk) 17:26, 15 February 2018 (UTC)
 * Yeah, I'm surprised no one has modified that yet two weeks after it was found out. I would modify it but I can't be bothered looking for new references. AlphaBetaGamma DeltaEpsilonZeta 09:18, 28 February 2018 (UTC)

Perhaps I can take to liberty to modify it. It'll be a few days to look up the proper sources however. nocturnalDEF NocturnalDef (talk) 18:59, 1 March 2018 (UTC)

New Theory: The Andromeda Galaxy is roughly the same size as the Milky Way Galaxy
According to a recent research by the International Centre for Radio Astronomy Research, the Andromeda Galaxy is roughly the same size as the Milky Way Galaxy. Should we change the size of the Andromeda Galaxy accordingly?

Source: https://www.icrar.org/cosmic-collision/

Original Research Paper: https://s3-ap-southeast-2.amazonaws.com/icrar.org/wp-content/uploads/2018/02/13131736/m31-escape-velocity.pdf

Xindeho (talk) 15:33, 5 April 2018 (UTC)


 * See-also Talk:Andromeda_Galaxy/Archive_2 William M. Connolley (talk) 16:02, 5 April 2018 (UTC)


 * I am confused. The source says that the Andromeda Galaxy and the Milky Way Galaxy are both roughly the same size. Does it mean the size or the mass of the galaxies? Other sources used in the article state that the Andromeda Galaxy is much bigger than the Milky Way Galaxy and it contains more stars as well. Xindeho (talk) 05:38, 10 April 2018 (UTC)

M32p
ok a sister galaxy to milky way, eaten by andromeda. thats a very big thing, that really existed, and is highly notable. i know we dont know much about it, but i think it deserves an article.(mercurywoodrose)50.193.19.66 (talk) 17:29, 23 July 2018 (UTC)

How massive is Andromeda?
Astronomy Magazine is going on and on about how astronomers have now (finally) discovered that the Andromeda Galaxy does not weigh as much as it once did:

http://www.astronomy.com/news/magazine/2018/02/adromeda-is-the-same-size-as-the-milky-way

What does the actual Science say? I don't think that one single study should trump dozens of previous ones. Does the main article need updating? Jehannette 10:30, 28 July 2018 (UTC)Jehannette

Milky Way Size
ESA researcher found that the Milky Way is much greater than expected: http://sci.esa.int/hubble/61198-hubble-and-gaia-accurately-weigh-the-milky-way-heic1905/

Should we change the first paragraph? — Preceding unsigned comment added by 2A0A:A540:EE45:0:A537:480:D78:8ABB (talk) 19:51, 11 March 2019 (UTC)

It would be nice to be able to cite actual publications instead of bare urls. Also, an effort should be made to outline the situation instead of simply replacing the old, well-referenced number by a new number copied off some press release. It is extremely difficult to estimate galaxy masses with any accuracy, and there are different methods which need to be explained. The concept of virial mass needs to be explained. This 2006 paper finds estimates an 8:10 ratio for Milky Way to Andromeda masses. This is compatible with other similar results published during the 2000s. This article needs to figure out how old and how well-established this result is, and if necessary explain that it is outdated, or at least has become less certain than it used to be two years ago.

It appears we have both a 2018 study which lowers the estimated value for the Andromeda Galaxy and a 2019 study which raises the value for the Milky Way. We need some reliable secondary source which puts these two factors in perspective and outlines if and to what extent mainstream opinion has been affected by this. --dab (𒁳) 11:18, 6 April 2019 (UTC)

Does M31 spin clockwise or counter clockwise by our perspective?
Has anyone seen a listing that compares cw and ccw rotating spiral galaxies? It seems like this should be an important statistic to include in articles. Sometimes easy to tell, but for M31, not perpendicular enough for me to be sure. Does anyone know for M31? Any sources? Tom Ruen (talk) 22:55, 27 April 2019 (UTC)
 * I see this Galaxy_Zoo. Tom Ruen (talk) 23:05, 27 April 2019 (UTC)

Distance modulus and absolute magnitude
According to the latest estimations (2012), M31 is located at 766 ±21 kpc or ~2.5 million l.y. In this case, its absolute magnitude listed in your frame at right of you main page cannot be -21.5 but -20.98 (and to get M=-21.5, it means that M31 'd be closer than 2.2 million l.y. was has been invalidated since 1998). You will find additional data at https://www.noao.edu/meetings/m31/files/distance-to-m31.pdf -- luxorion — Preceding unsigned comment added by 2001:7e8:cc44:4200:895a:681:378f:ea04 (talk) 16:14, 7 May 2018 (UTC)

value for distance?!
In the infobox a value is given for the distance that, according to a footnote, is the simple average of 4 published distance determinations. This is a) original research and b) wrong: since some determinations have a better formal accuracy than others, they should be counted with a higher weight when averaging. Also the selection of the contributing values must be justified: the determinations must be independent (e.g. a later one not being in improved value of an earlier one partially based on the same data). I will flag the value; how best to resolve this? Tom Peters (talk) 12:53, 24 October 2019 (UTC)

WHAT THE HELL HAPPENED TO THE MAIN IMAGE ?????
It looks like the article has been vandalized by numerous IP Users. One of these saw the removal of the Main Image. WHAT HAPPENED ???????????????????????????? — Preceding unsigned comment added by THE COLOSSAL GALAXY NAMED IC1101 (talk • contribs) 06:47, 22 July 2020 (UTC)


 * I've put things back together as best I can and will keep an eye on it, but the article should probably be reverted to back before the silliness began. Eastcheap (talk) 11:49, 22 July 2020 (UTC)

Ok.... THE COLOSSAL GALAXY NAMED IC1101 (talk) 00:51, 23 July 2020 (UTC)


 * Would someone mind semi-protecting the page? I have seen it been vandalized tens of times, and am getting annoyed. PNSMurthy (talk) 03:25, 23 July 2020 (UTC)

Ok. I will try to tell an administrator to semi protect the page. Im sure this is a good article, I don’t want it to become bad. After all PNSMurthy, The Andromeda Galaxy is also my favorite galaxy, Like you. My opinion tells me that it is 261,000 Ly Across !!! THE COLOSSAL GALAXY NAMED IC1101 (talk) 04:54, 23 July 2020 (UTC)

I have already raised the issue in the teahouse, I was planning to approach an admin myself.PNSMurthy (talk) 05:34, 23 July 2020 (UTC)
 * Hi folks. I saw 's request at WP:TH and have given the page 3 days semi-protection. If vandalism should resume after that time, make another report at WP:RFPP, please. For future reference: if you see vandalism coming from similar-looking IPv6 addresses, do consider taking a look at what's called the '/64 range'. These are the legitimately-changing multiple addresses used by just one individual. Thus 2A00:23C5:5300:9101:24BE:11FE:43EB:7C82 appeared to have made just this one edit when, in reality, they actually made all these, each getting their own warnings, but each not quite appearing to merit a block in their own right. (Just put /64 at the end of the Special contributions url to see all their edits, and warn appropriately, mentioning previous IPv6 IP edits in any such warning if they are linked in this way.) I would have blocked the editor across the entire /64 range had I seen their vandalism reported at WP:AIV at the time. But we block to avoid disruption, rather than as retrospective punishment. So if the same /64 range of addresses causes problems again, please report to them to WP:AIV as, cumulatively, they've definitely racked up enough warnings to merit an immediate block. If you do report them, feel free to mention 'vandalism across the /64 range' - I sometime forget to check that possibility, and so can underestimate the problems that one person is causing by only seeing their partial edits. Having you guys check and lay the groundwork for a block makes the life of admins at AIV a helluva lot easier, and reduces the time needed to investigate each report and the appropriateness of any vandalism report. I often get frustrated there that reports are made too soon, and that an editor hasn't been warned sufficiently. In this case, I think it was the reverse situation. Regards, Nick Moyes (talk) 12:25, 23 July 2020 (UTC)

IP Users... They disrupt Wikipedia... I too, was an IP User Named 122.2.30.162. I could not edit the List of largest stars, But I want to revert Nussun 05’s String of adding inaccurate Sizes, which has stopped very recently. I instead wanted to have an edit request to remove inaccurate sizes so I created Stop adding inaccurate sizes because of this. Now I have an account about astronomy with 340 plus edits. It is soon hopefully reaching 400 then 500 edits and I have already exceeded a few users .THE COLOSSAL GALAXY NAMED IC1101 (talk) 16:25, 23 July 2020 (UTC)

Mass estimates - dark matter
Under Mass estimates can we add an actual estimate for the dark matter mass in the galaxy or its halo. Or do the sources not calculate this ? - Rod57 (talk) 12:11, 30 April 2021 (UTC)

The name Andromeda
Is definitely name after an ETHIOPIAN princess. What version of The Odyssey have you read where it says Phoenician ? Paragraph 3 line ONE it clearly says αἰθίοπας, or Aithiopas, Ethiopia, or Black Skinned, Kushite. Allanana79 (talk) 23:47, 5 June 2021 (UTC)

Swift tour of Andromeda links to swift tour of M31
I do not know where to find the proper swift tour or how to link to it but perhaps someone can fix it. User random numbers (talk) 00:52, 20 May 2022 (UTC)

Let's talk about Andromeda's size for a bit
Okay, I'll get straight to the point. Citing this source from 2006 by Chapman et al, the article says this:

"In 2005, astronomers used the Keck telescopes to show that the tenuous sprinkle of stars extending outward from the galaxy is actually part of the main disk itself."

Except it doesn't? Nowhere in the paper does it say that the halo of Andromeda belongs to the stellar disc, more so that it was the delimitation of its extent. In fact, looking at the press release document, they said this:

"In addition to being metal-poor, the stars of the halo follow random orbits and are not in rotation. By contrast, the stars of Andromeda's visible disk are rotating at speeds upwards of 200 kilometers per second."

So, here's the thing. I've been working on an article related to galaxy sizes for quite a while now, so I think I should give my views. Haloes, the "tenuous sprinkle of stars", or any diffuse protrusions (such as radio jets) are almost never used in the literature to define the size of a galaxy (as stated in Talk:IC 1101 where this became an issue). From the bit of sources I can find, galaxy sizes are almost always defined via isophotometry in optical/near infrared, fractional light radius (half-light, and others use 90% light), Petrosian radii, or scale lengths (logarithmic luminous flux, I think, where light is ~2.718 times less the nucleus). If you are using NED for a while, they mostly use the first two (because they give the largest diameters).

Speaking of NED, they give a physical size to Andromeda here to be about 46 kpc (150,000 light years), via the B-band isophote in RC3. 2MASS gives an almost similar diameter. But the 220kly value has been gone for quite a long time now, so I am too afraid to edit it without consulting it here first. Either way, thoughts? SkyFlubbler (talk) 18:01, 16 July 2022 (UTC)

capitalization of "galaxy"
Looking at a few of the easiest sources to access, I get the impression that capitalizing "galaxy" is not preferred, likely because it's not actually part of the name. I don't see that this has been raised in the past, and I can't easily access many of the sources, which is why I am looking for discussion about whether this might need to be renamed. ~TPW 16:44, 23 November 2022 (UTC)


 * No, it should not. Every instance that I can find refers to this as "Andromeda Galaxy" with the uppercase G. And what you said "likely because it's not actually part of the name" is not true; "Andromeda" alone refers to the constellation, and the instance of "Galaxy" is part of its title (much like City of London), so it should be capitalized. SkyFlubbler (talk) 16:57, 3 December 2022 (UTC)

[O III] Emission Arc discovery
https://www.astrobin.com/1d8ivk/ https://iopscience.iop.org/article/10.3847/2515-5172/acaf7e

It appears a new emission arc was detected around and inside Andromeda. Note worthy for the page? Could probably be a good image in that Astrobin article to throw in as well. Mrblue630 (talk) 18:54, 9 January 2023 (UTC)


 * Yes!
 * I added in a section on the
 * Andromeda Galaxy
 * page:
 * https://en.wikipedia.org/wiki/Andromeda_Galaxy#Discovery_of_the_M31_[OIII]_emission_arc
 * and mentioned here that it could maybe be its own page as more info comes in. Might be good to wait until there is more coverage in mainstream science press other than the few I cited in the new section before making a new paper. If a new page gets removed as non-notable, it's hard to get it back even after it is notable. For now, I'd recommend adding new info to the section above.
 * Would be great to add a photo. I don't see any citation on the image on AstroBin of the license of the image. Needs to be Creative Commons to add to Wiki Commons, to add here.
 * I'll see if I can get the discovers to add it. Have you seen an official copy with the license listed? ElizaBarrington (talk) 06:46, 16 January 2023 (UTC)