# The Milky Way and Andromeda Collision **URL:** \ **Category:** Factual Questions\ **Created:** [June 8, 2018, 5:05am UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664 "2018-06-08T05:05:45Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![moes\_lotion](https://avatars.discourse-cdn.com/v4/letter/m/7ba0ec/32.png) [@moes\_lotion](https://boards.straightdope.com/u/moes_lotion)\ **Post date:** [June 9, 2018, 12:53am UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/21 "2018-06-09T00:53:04Z")
> [@septimus](#): > > Nitpick: Will the two galaxies coalesce, or will they pass through each other and finish as two separate galaxies with distorted shape? [Here’s a photograph of five colliding galaxies.](https://www.nasa.gov/multimedia/imagegallery/image_feature_1408.html) That webpage seems to suggest that the collision might change the galaxies from ‘spiral’ type to ‘elliptical’ type. As per the article linked by **septimus** above, of more concern to our distant ancestors than our sun colliding with another star is the chance of getting fried by intense x-ray emissions from colliding gas clouds in the two galaxies, or an increase in supernova formation. Better have lots of sun screen ready. ---
**Author:** ![Chimera](https://avatars.discourse-cdn.com/v4/letter/c/8e8cbc/32.png) [@Chimera](https://boards.straightdope.com/u/Chimera)\ **Post date:** [June 9, 2018, 1:02am UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/22 "2018-06-09T01:02:28Z")
Well, the Earth will have been rendered uninhabitable long before then, so no worries. ---
**Author:** ![P-man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/p-man/32/3606_2.png) [@P-man](https://boards.straightdope.com/u/P-man)\ **Post date:** [June 9, 2018, 1:25am UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/23 "2018-06-09T01:25:09Z")
That’s gonna be some dope shit to watch from heaven. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [June 9, 2018, 2:50am UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/24 "2018-06-09T02:50:36Z")
> [@Chimera](#): > > Well, the Earth will have been rendered uninhabitable long before then, so no worries. Nah, we got [that covered](https://arxiv.org/abs/astro-ph/0102126). ---
**Author:** ![Projammer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/projammer/32/559_2.png) [@Projammer](https://boards.straightdope.com/u/Projammer)\ **Post date:** [June 9, 2018, 3:42am UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/25 "2018-06-09T03:42:11Z")
> [@engineer\_comp\_geek](#): > > Stick around for a few billion years and maybe you can answer the question. 😛 I’ll bookmark the thread to bump it with an update. ---
**Author:** ![Roderick\_Femm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/roderick_femm/32/14875_2.png) [@Roderick\_Femm](https://boards.straightdope.com/u/Roderick_Femm)\ **Post date:** [June 9, 2018, 5:14am UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/26 "2018-06-09T05:14:46Z")
> [@Mijin](#): > > Finish as one galaxy according to most models. “Milkdromeda” I prefer “AndroMilkyda” as both more mellifluous and a better recognition of the relative hugeness of Andromeda compared to our little galaxy. ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [June 9, 2018, 8:45am UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/27 "2018-06-09T08:45:51Z")
Say that I load a bunch of magnets into an array of PVC pipe airguns. One magnet per pipe. I know shoot all of the airguns at once. Most likely, the magnets will attract each other in the air and land in clumps. If you think of the big bang as something like a grenade, with tiny bits of shrapnel that are a degree or two off from one another in heading, then yeah, it might seem implausible that they’d attract one another. But space is really fricking big and the particles that were ejected by the Big Bang were really small and really finely distributed. It’s like if you measured the angle of all of the light beams hitting the Earth from the Sun. You’d find that they were all so parallel that it’s difficult to believe that they actually aren’t. It’s not that the Sun isn’t radiating light in all directions, it’s that the particles are so small, there are so many of them, the distance is so great, and we’re so small, that it all ends up _seeming_ like the light rays are all parallel to one another. The magnets that are shot out of your PVC pipe have an easy time clumping, again, because they’re being ejected parallel to one another. Andromeda and the Milky Way are so tiny and they’ve traveled so far that, by the standards of the Big Bang and the Universe, they’re in parallel transit. No difficulty for them to attract one another. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [June 9, 2018, 1:32pm UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/28 "2018-06-09T13:32:25Z")
> [@moes\_lotion](#): > > …of more concern to our distant ancestors… Descendants. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [June 9, 2018, 1:47pm UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/29 "2018-06-09T13:47:12Z")
> [@](#): > > Quoth **Roderick Femm** : > > I prefer “AndroMilkyda” as both more mellifluous and a better recognition of the relative hugeness of Andromeda compared to our little galaxy. Our Galaxy isn’t little. It’s actually a fair bit above average in size, for a spiral galaxy. Though yes, the Andromeda galaxy is even larger. As an aside, a pet peeve of mine: “Andromeda” is a constellation, a region of the sky as seen from Earth containing stars in which the ancients imagined a picture. “The Andromeda Galaxy”, also called M31, is a galaxy which, as seen from Earth, happens to be in that region of the sky. Pedantic, I know, but it bugs me when people refer to the galaxy as just “Andromeda”. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [June 9, 2018, 10:28pm UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/30 "2018-06-09T22:28:47Z")
There was a recent report that someone had found stars beyond the edge of the galaxy in the galactic plane. IIRC, some these were twice the distance from the center as the nominal edge was. So going by that, the galaxy is much larger than it was previously thought. This does not surprise me. The edge of the galaxy, like the edges of the solar system and atmosphere, is not likely to be a sharp boundary, but gradually tapers off. But that will also be true of other galaxies, including M31. It’s virtually certain there are stars beyond its edge that we can’t see. At any rate, like most astronomical objects, the mass of galaxies is much more important than their size. And this discovery doesn’t change the mass significantly. ---
**Author:** ![Drunky\_Smurf](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/drunky_smurf/32/449_2.png) [@Drunky\_Smurf](https://boards.straightdope.com/u/Drunky_Smurf)\ **Post date:** [June 11, 2018, 5:29am UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/31 "2018-06-11T05:29:00Z")
> [@wolfpup](#): > > I’m fascinated by this picture (click to expand to full size): > [Andromeda if it were brighter - Imgur](https://imgur.com/EpuhHJa) > > It’s what the Andromeda galaxy would look like today compared to the size of the moon, if all the spiral arms were bright enough to see, despite the fact that it’s 2.5 million light-years away! > > That sucker is BIG – and getting closer every day! :eek: This is a super cool picture and makes me wonder if Andromeda would had been made up as a God like the sun and moon to ancient peoples. While the sun and moon “move through the sky” Andromeda would just sit there. Staring at us. And judging us. Which makes me wonder how religions might have shaken out and how that may have changed history and our current societies and cultures. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [June 11, 2018, 1:15pm UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/32 "2018-06-11T13:15:32Z")
Eh, I don’t think any southern cultures ever deified the Magellanic Clouds. ---
**Author:** ![Drunky\_Smurf](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/drunky_smurf/32/449_2.png) [@Drunky\_Smurf](https://boards.straightdope.com/u/Drunky_Smurf)\ **Post date:** [June 15, 2018, 6:30am UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/33 "2018-06-15T06:30:08Z")
You don’t think, or you don’t know? Because visually the image I am talking about and the one you are are very different. Here is the one I am talking about where Andromeda is at least 3-4 times bigger than the moon: [![Imgur](https://i.imgur.com/EpuhHJa.png "Andromeda if it were brighter") ](https://imgur.com/EpuhHJa) And the one you are talking about, from one of the most generous images I could find, from where they are just bright patches in the sky. [![](https://earthsky.org/upl/2013/08/meteor-Perseid-Magellanic-Clouds-Colin-Legg-8-11-2013.jpg) ](https://earthsky.org/upl/2013/08/meteor-Perseid-Magellanic-Clouds-Colin-Legg-8-11-2013.jpg) ---
**Author:** ![Wendell\_Wagner](https://avatars.discourse-cdn.com/v4/letter/w/8491ac/32.png) [@Wendell\_Wagner](https://boards.straightdope.com/u/Wendell_Wagner)\ **Post date:** [June 15, 2018, 7:23am UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/34 "2018-06-15T07:23:13Z")
The Andromeda Galaxy is about six times as wide as the Moon as seen from the Earth: > **[Yes, That Picture of the Moon and the Andromeda Galaxy Is About Right](https://slate.com/technology/2014/01/moon-and-andromeda-relative-size-in-the-sky.html)** > > In my line of business—trying to spread the word about science and trying to grind anti-science under my heel—I post a lot of articles with the word... ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [February 12, 2019, 2:31am UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/35 "2019-02-12T02:31:57Z")
> [@Projammer](#): > > I’ll bookmark the thread to bump it with an update. Well, here it is a few [del]billion years[/del] months later and it’s time for an update. No doubt many of you have seen Phil Plait’s blog about a refinement in the [calculation on when the big collision](https://www.syfy.com/syfywire/breathe-easy-you-have-an-extra-600-million-years-before-andromeda-crashes-into-us) will occur. Many will be happy to note that we’ve gotten a reprieve of some 600 million years. It’s not going to happen until 4.6 billion years from now. Or maybe you’ll be disappointed that you won’t see the fireworks until that much longer. Whatever, but check back in a year or so from now and the calc may be refined even more. BTW, note that M33, the Triangulum Galaxy is not actually in orbit around Andromeda. Doesn’t surprise me. Galaxies in general have only been in existence (at least in something like their current form) for about 10-12 billion years. That’s about the same order of magnitude as their orbital periods assuming they’re in orbit. Which means they really haven’t had time to orbit each other very much, if they actually are in orbit. Much more likely is that nearby galaxies throughout the universe are all on their first approach to each other and are mostly destined to collide sooner or later. ---
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [February 12, 2019, 3:50am UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/36 "2019-02-12T03:50:00Z")
> [@Mijin](#): > > Finish as one galaxy according to most models. “Milkdromeda” And then the Eddorians will take over the whole shebang. ---
**Author:** ![control-z](https://avatars.discourse-cdn.com/v4/letter/c/eada6e/32.png) [@control-z](https://boards.straightdope.com/u/control-z)\ **Post date:** [February 12, 2019, 6:31pm UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/37 "2019-02-12T18:31:02Z")
> [@dtilque](#): > > Many will be happy to note that we’ve gotten a reprieve of some 600 million years. It’s not going to happen until 4.6 billion years from now. Well heck. I’ve been waiting outside, guess I’ll go back inside for now. Keep us updated. ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [February 12, 2019, 6:42pm UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/38 "2019-02-12T18:42:23Z")
Just time for a cup of tea, I guess… ---
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [February 13, 2019, 8:40am UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/39 "2019-02-13T08:40:05Z")
> [@moes\_lotion](#): > > … our distant ancestors … Why do so many people make this mistake? The word you meant is “descendant.” ---
**Author:** ![Malden\_Capell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/malden_capell/32/5274_2.png) [@Malden\_Capell](https://boards.straightdope.com/u/Malden_Capell)\ **Post date:** [February 13, 2019, 9:29am UTC](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664/40 "2019-02-13T09:29:07Z")
Will there be many stars still around by that time? Won’t the Sun be near to dying at that point? Sent from my iPad using Tapatalk [Previous page](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664.md?page=1) [Next page](https://boards.straightdope.com/t/the-milky-way-and-andromeda-collision/815664.md?page=3)