Milky Way VS. Andromeda Galaxy

Question

As you all know in around 3.5 billion years time our galaxy the Milky Way is expected to collide with the Andromeda galaxy. This is approximately 2.5 billion years before our Sun is expected to become a Red Giant. My question to you is this. I do not think that the Andromeda galaxy holds nearly as much activity as ours does and I have heard little proof that it will do any serious harm. I know for sure though that when our Sun starts to die that Mercury, Venus and potentially Earth will get engulfed. The rest of the planets would then get ejected into interstellar space. I know that we will all be long gone by the time both of these happen but this is the kind of thing that truly fascinates me. Any websites or links would be great help!

Answer 1

Yeah, the timing is wrong.

Sure, stars won't collide.  And Andromeda may have less free gas and dust than the Milky Way.  But even without it, the first pass is going to compress huge amounts of gas and dust, which will create lots of stars - and many of the huge ones that go boom.  That could very easily have an effect on us.

Let's say that the Sun heats up (which it will, long before the Red Giant phase).  Does that mean that the Earth dies?  No.  We nearly have the technology right now (we have all the physics!) to save the Earth.  One proposal is to get a big asteroid into a funky figure 8 orbit between Earth and Jupiter.  We can steal orbital energy from Jupiter and give it to the Earth, expanding it's orbit.  And, calculations suggest that we have plenty of time.  We'd have to be stupider than we are now to miss this opportunity.  So, the Earth could survive to the White Dwarf phase, and have trillions of years left.  So, the merging of Milkdromeda could make a difference.

Answer 2

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Answer 3

The really cool thing about these two galaxies intersecting is that when they do, there is so much space in between stars in our galaxies that most likely there won't be any collisions.  Both galaxies will pass through each other like a qhost and then several millions of years later, gravity will take hold again and they will sort of dance around each other until finally they become a single enormous galaxy.  Yes..most likely the sun will already be in its Red Giant phase.  Most likely the Earth won't be engulfed but the sun will be close enough to boil the oceans away and make Earth completely inhabitable for human life.  So hopefully we have moved on by then, but if humanity does actually survive up to that point you would have to think...we wouldn't be even recognizable.  We would have evolved to a point where we could control things with our mind and such if it were at all possible.  But I likely doubt we will survive up to that point.  Sure would be interesting to see though.  Hope this helps.

Answer 4

Where did you hear this? I haven't heard about any imminent collision with Andromeda. Even 3.5 billion years away. I better check my Geico policy to see if I'm covered for extra-galactic acts of Gravity or nutrino bursts.  

Answer 5

" I know for sure though that when our Sun starts to die that Mercury, Venus and potentially Earth will get engulfed."

No, you don't.  Remember, our sun is constantly converting matter into energy then radiating that energy into space.  That means the sun's mass and therefore it's gravity is contantly going down.  This mean each planet is getting slowly farther from the sun.  By the time the sun goes red giant, it is possible Earth will be far enough from the sun to survive.  Also, our decendents will hopefully still be alive and by then should have the techology and economics to simply move Earth to a safe distance.  Maybe they'll put it in a museum somewhere.  

Answer 6

I'm of a different opinion concerning some of your points.  First, the outer planets will not be ejected by the sun becoming a red giant.  Planets *could* be ejected, though, by a close pass of another star, like when the galaxies collide.

What do you mean, Andromeda galaxy doesn't hold as much activity as the Milky Way?  Whatever that means, the harm it might do is because of the huge amount of mass that will be streaming through our galaxy.  Billions of stars will be sent hurtling out of their galactic orbits.  It might also cause harm to life-bearing planets because of the high speed collision of gases and the resultant radiation.

Answer 7

This is an interesting one. In addition, Sky & Tel had an article looking at the future of the planet and the sun in August (I think) 2007. The sun is expected to become a red giant in nearly 7 billion years, but of course it will be swelling before then. And the planet will be uninhabitable in about a billion years, although the sun will only be a little hotter.

http://pqasb.pqarchiver.com/skyandtelesc...

EDIT: Riiiighht . . . I'm not offended by a thumbs-down or being told that my answer is shite, but I'm not sure what you wanted. You said "My question to you is this", and then didn't ask a question anywhere. What is the question?

Answer 8

i don't have any links, but i think your timing is wrong.... to my knowledge andromeda will start merging with the milky way in about 4-5 billion years, and the sun will go out in about the same ammount of time (5 billion)

the objects in a galaxy are huge, and moving fast, but they're also spaced ridiculously far apart, any collisions will be a pure chance  occurance, it's not even a mathmatical certainty atm.

"Where did you hear this? I haven't heard about any imminent collision with Andromeda. Even 3.5 billion years away. I better check my Geico policy to see if I'm covered for extra-galactic acts of Gravity or nutrino bursts. "

it's been common knowledge for 5 years or more now...

also upon looking further, it appears we were both right.... it's estimated time is 3-4 billion years

it's too bad it's not happening sooner... like in just a few years down the line... being able to study that merging in great detail could potentially solve a vast number of unanswered questions, or prove/disprove countless theories that we haven't yet had the chance to study in detail.

Answer 9

A galaxy is not a solid object. Two galaxies colliding is a more a merge than a collision. Besides the centre of the galaxy, perhaps none of the stars will collide with the stars of Andromeda.

You have to evaluate the probability of a collision: 1 per 1000, 1 per 1,000,000?

The centre of the galaxy is an other story. The density of stars is very high, especially if there is a black hole.