Apparently Andromeda is going to get here in 5 billion years and is 2.5 million light years away. I tried to work this out myself but I'm not sure I believe the answer..

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    $\begingroup$ Please show your work. $\endgroup$ Nov 26, 2023 at 11:25
  • $\begingroup$ As I am sure my work is probably wrong I would rather not... $\endgroup$ Nov 26, 2023 at 11:27
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    $\begingroup$ Please show your work even if it wrong. Showing your work acknowledges that you have shown effort. The fact that you were wrong is the reason you asked this question: astronomy.meta.stackexchange.com/a/429/35206 $\endgroup$ Nov 26, 2023 at 12:42
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    $\begingroup$ It's not bad to show something where there is a flaw in the math. It's worse to not - and not learn from ones own mistakes, and repeat them. The aim of this site is that everyone can learn from questions. Also especially in astronomy and astrophyics: a factor of 10 is sometimes easy to explain when starting with different assumptions about the initial conditions, making neither calculation wrong. $\endgroup$ Nov 26, 2023 at 12:42

1 Answer 1


About 670,000 miles per hour

Thanks to blueshifting, we have been able to pin the velocity of the Andromeda Galaxy at about 300 kilometers per SECOND, which when converted, yields a approximate value of about 670,000 mph.


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