Viewing a single comment thread. View all comments

earthman34 t1_j1grbww wrote

These things are not trivial to calculate at universe-spanning distances where relativistic effects and universe expansion become factors. Doing some simple math and ignoring these factors, at it's current velocity based on measured red shift, the Saraswati supercluster would be about 280,000 light years farther away in a million years, and 280 million light years in a billion years, although that later figure would be off by an increasingly large factor. The Andromeda galaxy is moving towards our galaxy at a much lower velocity, so in a million years it would be around 1000 light years closer, and in a billion years about a million light years closer.

FYI I am not a professional astronomer or cosmologist.

11

melanthius OP t1_j1gzpgg wrote

I think the numbers for saraswati are helpful, but I was trying to ignore the effect of andromeda approaching Milky Way. What would it be like for some object much closer than saraswati but one that is not approaching us specifically?

Is andromeda blueshifted then? Edit- I see now that it is from a google search. That makes it a bad example for this

−1

Gabougi t1_j1hsvjh wrote

The constant for the universe expansion is (70km/s)/Mpc, so if we approximate MW-Andromeda to be 1 Mpc, in a million years it would be ~233 light years further. In real life, thought, it has a relative speed towards us and the gravitational bound between our galaxy and Andromeda is enough to render the expansion useless

2