Milky Way to collide with Andromeda Galaxy

[Deepak]

http://news.yahoo.com/s/space/20051212/sc_space/galacticcollisionsfastandfrequent

It doesn't appear that the Milky Way has a collision rich history, van Dokkum said, mainly because it has a very large, intact disc that a merge or collision would have disrupted. But that could change soon-- the Andromeda galaxy M31 lurks just 2.3 million light years away and is on a crash course for the Milky Way.

"The Milky Way will collide in the future, in about 4 billion years with the galaxy Andromeda and that collision will lead to formation of a much bigger galaxy," van Dokkum said. "So we have that to look forward to."

http://www.space.com/scienceastronomy/astronomy/galaxy_collides_020507-2.html

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[font=Verdana, Arial, Helvetica]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.
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What will happen if we and our planet survives till then, and when is Sun going to burn out?

 

[K.I.L.E.R]

I'm just thankful that I will be DEAD before that happens. It might be a beautiful sight but it could lead to a painful death.

 

[Moloch]

I'll mark my calender...

 

[Bobbler]

I'm just thankful that I will be DEAD before that happens. It might be a beautiful sight but it could lead to a painful death.

I don't imagine it'd be _that_ painful; if earth collided with some other planetary object of substantial mass it would probably initially ignite the atmosphere and the planet would break apart very shortly after -- you'd be dead within a couple seconds regardless.

I think it would be a rather fantastic way to go (as long as you're old by then -- dying young isn't something I'd look forward to). To be around at the end of the earth... Hah, the way it's going we may all see that, though.

I doubt humans will even be around in 4 billion years anyways -- we'd probably have blown ourselves to bits long before then or substantially evolved and we would be the content of history lessons.

 

[3dilettante]

I think most astronomers believe that the collision would most likely be very boring to anyone not a couple million light years distant.

The likelihood of any two stars colliding is incredibly small, since galaxies are mostly empty space.

What we'd likely see if we were around to spectate would be two misshapen spirals swinging through each other. Each individual star would most likely not know much was going on, though an outsider would notice that its orbit would change dramatically over the course of millions of years.

There could be a few collisions and a number of near misses, but this solar system or its remnants run a good chance of not knowing what the big fuss is about.

What I'd like to see is what would happen when the ultramassive black holes that exist in the center of the two galaxies will do.

 

[arjan de lumens]

Galaxy collisions are AFAIK not usually that dramatic at the individual star level (unless you are hit with the galaxy center); if we're unlucky, some star might pass close and throw lots of comets at us or throw the Earth out of orbit, but I don't think the risk of that is much higher than what we're already experiencing in the Milky Way. With a bit of better luck, the Sun itself is thrown out of orbit, taking Earth with it; something like that would be absolute killer to astrology, but not really affect life on Earth much otherwise.

 

[nutball]

Well you might also like to compare the predicted timescale (3-4 billion years) with the predicted remaining lifetime of the Sun before deciding to be worried

As has already been pointed out, galaxy collisions are generally quite gentle affairs. Granted the tidal interactions will likely cause waves of star formation, but that's not unusual.

Of course the media love the instant giga-death angle in such stories

 

[Deepak]

I remember reading somewhere (few days back) that a comet which could potentially strike Earth has been discovered, am trying to find out link.

 

[Deepak]

http://neo.jpl.nasa.gov/risk/

Intersting link.

This asteroid is a potential risk....

http://neo.jpl.nasa.gov/risk/a99942.html

 

[Guden Oden]

it would probably initially ignite the atmosphere

What kind of pseudoscience is this? It must be something you heard on some bad SF TV show. The atmosphere can't "ignite", if it could it would have done so already - millions of years ago - from all the lightning strikes, forest fires and volcano eruptions (just to mention a few natural sources that can set things alight).

The earth's atmosphere isn't a fuel, if it was, all we'd need is an air intake to run our cars on free and abundant energy.

As for what would happen sort of depends on the speed which the collision occurs with. And to some extent wether the other object has an atmosphere as well. If the impact is sufficiently rapid, both objects would pulverize and not reform a new planet. If it was slower, (most of) the debris could fall back in on itself, or perhaps not launch into orbit at all. Unfortunately the planets would likely liquify from the release of friction energy during impact, it would take (tens of) thousands of years for the new body to coagulate again...

Of course this assumes a solid planet hitting us. A gas giant might just swallow us up...

 

[Bobbler]

I was thinking a solid rock the size of the moon or bigger hitting the planet at a rather ungentle speed (as that would be the most violent encounter we could probably have) -- which would probably burn everything on the planet upon impact, I imagine. Forgive my term 'ignite'.

I didn't even think about the fact that the sun probably won't be cooking still (what's the timeline on the sun's life?), or the possibility that earth's orbit could be lost (assuming that the sun is still around).

 

[AlNom]

Most collisions will be at the center of one of the galaxies. It'd be phenomenal to see the events there.

 

[AlphaWolf]

Don't make me pull this galaxy over...

 

[wireframe]

Alright...stop beating around the bush...what's this gonna do to my insurace premium?

 

[Vadi]

Our sun will probably swung out of its orbit and yes we will die of radiation AFAIK.

Then there is the small chance we'll get hit by the beam of gamma rays coming out of the polar regions of the newly formed massive black hole fed by huge amounts of matter.


edit:
Before that maybe we'll get hit by two gamma beams of two massive black holes before they fuse together.

edit2:
Reminds me of a little story:
In elementary school I proudly told a friend of our sun's fate of becoming a red giant and eating us in a hellish fire. Unfortunately he burst out in tears and I had to tell him several times this would happen in a distant future.

 

[bouy]

Nothing major would happen during the collision.

Right up to it it would be cool to see a heaping spiral galaxy outside at night and maybe a part of it during the day.

There are two things that can happen, first it'll pass through and go by with little change. Second the black holes can merge at the centers and cause our galaxies to merge, and last in a few simulations my astronomy professor showed they our galactic cores would orbit each other for a while then spirl off but the shape of both galaxies would end up extremely mishapened. And that our cluster of stars could spiral out into space.

http://antwrp.gsfc.nasa.gov/apod/colliding_galaxies.html

 

[KimB]

Well, the merger of the two galaxies really isn't of much concern for life on Earth. At around 4-5 billion years, our sun is going to go red giant anyway, at which time the Earth will be enveloped within the sun. Long before that, of course, we are likely to have a massive asteroid impact that will eliminate all life on Earth.

So, we really need to move off this rock at some point. That's the only way to survive.

The merger of our galaxy and Andromeda will be quite gentle for most of the stars involved, so if we are at the point where we can populate planets around other stars (assuming habitable planets occur with some reasonable frequency), then the chance we will survive the merger is pretty much unity. The sun being thrown out of its orbit isn't a problem as long as the mass that does the flinging doesn't pass within a few AU's (as long as it's far enough away, the orbit of the planet will be barely disturbed, as it will feel roughly the same pull).

If the human race can ever move off of the Earth, then it is likely that we will not die until the end of the Universe (either heat death or the big rip).

 

[Druga Runda]

instant giga-death angle

now that is the expression for the future... megadeath is beyond us... gigadeath

 

[arjan de lumens]

Tried to do some additional reading on what the results of galaxy collisions are. Apparently, a head-on collision between two spiral galaxies (both the Milky Way and the Andromeda are more or less spiral galaxies) is believed to result in a large elliptic galaxy, and such galaxies are generally plagued by a lot more close encounters between stars than spiral galaxies, possibly making them very unsuitable for sustaining life.

Then again, in 4-5 billion years, humanity is very likely either extinct for other unrelated reasons, or it has developed its technology far enough to easily handle any dangers of living in an elliptical galaxy. In that time-frame, there should also be a lot more metal-rich stars around, which means that there will be a lot more habitable planet systems around than what is the case today.

 

[Druga Runda]

Tried to do some additional reading on what the results of galaxy collisions are. Apparently, a head-on collision between two spiral galaxies (both the Milky Way and the Andromeda are more or less spiral galaxies) is believed to result in a large elliptic galaxy, and such galaxies are generally plagued by a lot more close encounters between stars than spiral galaxies, possibly making them very unsuitable for sustaining life.

Then again, in 4-5 billion years, humanity is very likely either extinct for other unrelated reasons, or it has developed its technology far enough to easily handle any dangers of living in an elliptical galaxy. In that time-frame, there should also be a lot more metal-rich stars around, which means that there will be a lot more habitable planet systems around than what is the case today.

pfffttt 4-5 billion years fast forward if humanity survives it will equal god, the omipotent one. The constraints of the matter will surely be long behind us. I think it's odds on to say that any opportunity the universe presents or rule that holds it together will be thoroughly examined by than.