The end of days will at least be fun to watch
The andromeda galaxy is currently about 2.5 million light years away from us. Go out tonight to see andromeda and the light hitting your eye left andromeda 2.5 million years ago, before dinosaurs were really getting going here on earth. In another 4 billion years it’ll be much much closer though- it will be right on our doorstop. Although the universe is expanding and so galaxies are rushing away from us, andromeda is speeding towards us. When it arrives, It’ll be an almighty collision.
Of course by this time the sun be entering its final stages, swelling up into a red giant stage where it will be bigger than the current orbit of Venus. Earth, and life as we know, it is doomed, but at least it’ll be fun to watch.
Milky Way sure to smash into Andromeda — in 4 billion years
It’ll not happen anytime soon, but the Milky way is set to crash into our neighboring galaxy, andromeda. On the large scale, everything is moving away from everything else as the universe expands. But sometimes gravity wins the battle against expansion. In about 4 billion years the milky way and andromeda will collide. Stars are far apart so there will not be any head on star collisions -imagine a few grains of sands moving past each other. But the pull of gravity will likely throw our Sun into a completely different part of the galaxy. These collisions play a big role in the probability do finding life elsewhere in the universe, as we know life takes a long time to develop and these sort of unstable events could kill off early life. No need to worry about this collision though. In 4 billion years our Sun will have used up all its fuel and will have started puffing up into a giant star destroying any remnant life on Earth anyway.