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Study Details What Happens When Galaxies Collide
Aspiring Astronomer writes: According to a recent study, when two galaxies of a similar mass collide, both galaxies will begin producing more stars. However, when one galaxy considerably outweighs the other, the larger galaxy begins producing more stars, whereas the smaller galaxy's star production begins to slow. This may be because the larger galaxy is able to draw gases from the smaller one, resulting in the formation of more stars. The Milky Way may experience a collision of it's own, because the Andromeda Galaxy is moving towards us at speeds upwards of 200,000 miles per hour. No need to worry, though; this collision is a few billion years away.
Yes, that galaxy is indeed blueshifted. Who told you that "all the stars" are redshifted? When you look at the night sky, you'll see about the same number of blueshifted as redshifted stars, since the vast majority of them are in our own galaxy and we're all just revolving around the center. And the galaxies in our immediate vicinity are kind of clumping together, not expanding. When you look at objects outside our local cluster of galaxies, yes, those do all appear redshifted. The further they are, the more redshifted they appear. And that indeeds indicates that the universe is expanding. But in our local neighbourhood, there's plenty of blueshifted stuff.