h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

The Milky Way, the galaxy we know and love so well, has only another 4 billion years before we collide with our bigger neighbour, the Andromeda Galaxy. In a collision that will last 2 billion years, the two galaxies will merge to form a giant elliptical galaxy, without the spiral arms.

Because galaxies are mainly empty space, the stars won't actually collide with each other, even though the galaxies will.

The nearby Triangulum Galaxy will probably also get in on the act and join in the merger, although it's not clear whether it will meet the Milky Way before or after the big crash.

Should this be viewed as a hostile take over?

We've observed (well, I say "we" - astronomers have observed) distant galaxies colliding, and in the pictures they always seem a bit messy - lots of coloured gas or dust or ectoplasm or whatever. So, what's all that about then? Is it the black holes at the centre merging and then spitting it all out?

There's lots of interstellar dust, and it's travelling along with our galaxy. The other galaxy will have its own collection of dust. So when the two collide there's be a giant "dust wall" at the plane where they meet.

I can't wait.

And yet what, on this galactic scale, could possibly hoover up all that dust?

Nighthoover?

He said it, not me.

Will it be catastrophic for life on earth? What chance critical orbits won't be thrown out of kilter?

I wonder will there be life on Earth in 4 billion years. Well, there was some sort of life here about 3 billion years ago, so it is conceivable.

I don't think it will affect the orbit of the Earth around the Sun, but you never know.

Why shouldn't life continue? So long as we don't fry the earth while the oil and coal lasts, that is.

Gnomon; "There's lots of interstellar dust, and it's travelling along with our galaxy. The other galaxy will have its own collection of dust. So when the two collide
there's be a giant "dust wall" at the plane where they meet."


Where there's dust... there's a hoover! Surely the second coming... hmmm.... a bit later than anticipated, but that does seem to be a pre-requisit with second-comings... Which means... of course... that h2g2 must still be going at the point of the second coming

We'll be gone long before then. In about 800 million to 1 billion years, all life on earth will be wiped out by the expanding and brightening sun while the out core freezes removing our protective magnetic field.

DOOMED!

http://en.wikipedia.org/wiki/Timeline_of_the_far_future

*outer core

But, that can't be true!; the prophet said he was stuck here... forever... in order for the second coming, h2g2 must still exist... therefore the earth must still be here.... or We've taken the website into outer space by them!

OK, 800 million. Still plenty of possibilities, considering we've been here (humans) so small a proportion of that so far.