What will happen when the Milky Way collides with the Andromeda galaxy?

That's a good question. Andromeda actually may or may not collide with the Milky Way in about 3 billion years (at that time, the Sun should still have 2 billion years to go.

Galaxy collisions actually aren't rare, we can observe them happening all across the sky. When galaxies collide, their stars don't hit each other, there's so much empty space that it's very unlikely two stars would hit. But the gravity of the two galaxies distorts them both beyond recognition and the stars in them will get all mixed up.

Such a collision would be bad news for planets like Earth. If an Andromedan star passed close by, its gravity would disrupt the Solar System. This could shift the Earth's orbit in a number of ways, all of them bad. We could be knocked into either a closer or further orbit, into a more eccentric one, or out of the Solar system altogether! And even if out orbit doesn't change, a passing star could disrupt the Oort Cloud, sending numerous comets into the inner solar system. A collision with one of them would be significant enough.

(As an aside: note that some people have speculated that the Sun has a brown or red dwarf companion star that orbits at a great distance and periodically disrupts the Oort Cloud. The comet impacts produced thereby are blamed for periodic extinction events on Earth. But this theory has no empirical evidence and is fairly dubious)

That's how it would impact the Earth (or other planets with similar biospheres). Check out this article for more of the info that you're looking for:

http://www.space.com/scienceastronomy/astronomy/ga...

Thankfully, we have three billion years to prepare. So, if you haven't put together your galactic collision survival kit you've still got some time to gather your emergency supplies.

You should also check out information on the Galactic Habitable Zone. Basically, only certain areas of the galaxy are suitable for complex life (which requires a terrestrial body around the right type of star in an orbit that is stable for over a billion years).

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

Life on earth will be extinguished far before the collision. Our

galaxy has more gravity than Andromeda which will pull our

neighbour in our direction and there will be plenty of fireworks,

with a new and larger galaxy which will start forming solar

systems. I wonder where my burnt out bones will end up.

When you think about this matter, it makes you wonder if

the saying "a little knowledge is a dangerous thing" is not

the greatest truth we will ever know. I study astronomy, and

every day there are some new findings which only lead us

closer to this greater truth, that we are so insignificant and

it is a waste of time and money to research ahead, and even

more so the folk that are willing to pay for a space travel?

I think it would be better that this money should be sent to

the Gates Foundations to ease the discomfort of the poor,

the sick and dying in Africa. We live off their misery and,

perhaps when Andromeda does crash into us, finally

everything may be the other way around. Think about that.

When two galaxies collide, it looks spectacular to an astronomer millions of light years away, but the stars in a galaxy are so far apart that if you're living on a planet orbiting one of them, nothing much happens. It's highly unlikely that an Andromeda star will come close enough to the solar system to wreak havoc. It's just as likely that in the next 6 billion years a star in our own galaxy will come close enough to do that. If the solar system was hurled into intergalactic space, the only difference we'd notice would be that we wouldn't see the Milky Way spread across the sky any more.

Don't worry my friend,

Already, our Milkyway is in collision process with the Great Maggelan Galaxy (a small galaxy which is within the Milky way), and nothing happens. If and when Andromeda will come close to Milkyway, probably human race won't exist. Probably our sun will have been transformed to a Nova.

"Galaxies often crash into one another. Even our own galaxy has had others pass right through it. Don't worry though, galaxies can pass through each other quite safely. Stars are so far apart that the chances of two colliding is very unlikely"

http://www.kidsastronomy.com/galaxys.htm

Sleep Easy.

Most scientists agree that the Milky Way will cross paths with the Andromeda galaxy in about three billion years. Both galaxies are now spiral in shape, though Andromeda is about twice as large as the Milky Way.

The galaxies are separated by about 2.2 million light years (one light-year is about 6 trillion miles, or 10 trillion kilometers). That gap is closing at about 310,000 miles per hour (500,000 kph).

While a collision appears inevitable, astronomers admit that the sideways motion of Andromeda -- the galaxy’s speed perpendicular to its forward path toward the Milky Way -- could affect the encounter’s timing, but it has yet to be measured precisely. Dubinksi used an estimate of 12.4 miles per second (20 km per second) for his collision model.

"Even if the galaxies have a wider passage on the first pass, if they are on a bound orbit they are destined to merge eventually," Dubinski said. "If not on the first flyby, then within the second or third pass over the next 10 billion years, he added.

The clincher is gravity. Even if there’s enough space between the Milky Way and Andromeda to simply brush past each other at spiral arm’s length, their mutual gravity will ultimately win out, drawing the two galaxies together on successive flybys.

There's not much threat to any living organisms on planets in the two galaxies. A somewhat higher supernova rate, so if you're on an unlucky planet, you may get blasted. There is essentially no doubt that there are massive black holes in both galaxies. The combined mass of the black holes is around 10 million solar masses, and the two black hole will combine into a single massive black hole that is perhaps 20% bigger than this. But conservation of energy and angular momentum will keep the vast majority of stars and gas out of the black hole. You realize that the "massive" black holes are not as large as a really big star, even with all that mass.

Nothing, as it is all space between the stars. But it would if a star came too close to our Sun, as it would alter, drastically, the Earths orbit, so it could annihilate all life on Earth! Ooooh nasty!

http://haydenplanetarium.org/resources/ava/page/in...

try this page,I found it interesting,it says the sun and the stars might survive it,but a new galaxy might come out of the collision.

Not much will happen at all. Consider that the nearest solar system is 4.3 light years away.

The odds are that there will be nothing passing with 5 light years.

In most cases the galaxies pass through one another, without much overall change to either