# Cannibal Andromeda to Eat Milky Way?



## Drachir (Sep 5, 2009)

It seems that the giant galaxy Andromeda is a galactic cannibal that has already eaten a large part of the neighbouring Triangulum galaxy.  A galaxy with an apparent sweet tooth, Andromeda has its sights set on devouring the Milky Way in a few billion years.  

Astronomers prove next-door galaxy is cannibal - Science - Canoe.ca
Astronomers discover galactic cannibal


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## Dave (Sep 8, 2009)

Is that the galaxy it can eat between meals?


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## Ursa major (Sep 8, 2009)

Given the McThread currently running in World Affairs, I'm half surprised that the Mars comapny isn't suing Andromeda for a brand name violation.


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## Granfalloon (Sep 9, 2009)

Who's going to eat who?

"Although the largest, Andromeda may not be the most massive, as recent findings suggest that the Milky Way contains more dark matter and may be the most massive in the grouping." 

from:
Andromeda Galaxy - Wikipedia, the free encyclopedia

and if you follow the reference about the "dark mater", it seems they are making some headway in understanding more about it:

BBC NEWS | Science/Nature | Dark matter comes out of the cold


Besides the fact that the Andromeda Galaxy is about 2.54 million light years away from us, and therefore it could be awhile before this poses any real threat to us.

From Drachir's article: "The Milky Way and Andromeda are heading toward each other at about 75 miles per second. They are so far away from each other that the big crash is a few billion years away. And even that might be nothing more than a reshuffling of the night sky or the creation of one super-sized galaxy."


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## Sparrow (Sep 9, 2009)

Since our own Sun is due to expire in 4-5 billion years, and is very likely to exhibit behavior that will extinguish all life on Earth much earlier than that, other than an extra pair of clean underwear there isn't much we can do to prepare for it.

Sort of like worrying about dying from cancer while your trapped in a burning building.


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## Nik (Sep 10, 2009)

Seems like 'accretion' runs all the way from dust-grains up through galaxies to super-clusters...

Uh, a recent report that many 'stray stars' in Milky Way are remnants of umpteen Dwarf Galaxies may solve long-running puzzle. IIRC, simulations of galaxy formation make *hundreds* of dwarf galaxies around each 'big spiral'-- So where were they ??


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## reiver33 (Sep 10, 2009)

By the time Andromeda gets here the Earth will be a ringworld construct orbiting an artificially-fuelled Sun – obviously prime real estate! 

So I say we launch a pre-emptive strike _now_ to thwart their expansionistic aims! Just the kind of long-term project NASA needs to keep itself viable.


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## Granfalloon (Sep 15, 2009)

Andromeda is headed for us at 75 miles per second, right? Okay, 75 miles per second * 3600 sec/hr * 24 hrs/day * ~365 days/year*= 2.36 billion (2.36 times ten to the ninth power) miles per year. 

Andromeda is 2.54 million light years away. What distance is a light year (approximately)?

D=RT, T = D/R 

186,000 miles/sec = 186,000 * 3600 sec/hour * 24 hrs/day * 365 days/year = 5.87 * 1,000,000,000,000 (ten to the twelfth power) miles. At the rate that Andromeda is traveling, it will take roughly  [(2.54 million) * (5.87 * ten to the twelfth power)] miles divided by (2.36 billion miles per year) =  6. 313 billion (6.313 times ten to the ninth power) years to get here.


I think we'd better start working on a Gayan-centric galaxy soon. 

But wait...

Do you remember how you used to hate those word problems? (One train is headed east at this rate, the other headed west at that rate, when will they meet?)

What about our galaxy? Is it just sitting still waiting to be collided into by some big bully named Andromeda? 

Relative to the centre of the Local Group, our Galaxy is moving at roughly 200 km/s the other way. Therefore, the Local Group of galaxies (to which we belong) is moving at 600 km/s relative to the Cosmological Microwave Background radiation. (from: http://answers.yahoo.com/question/index?qid=20080903025801AAXuDc3 )


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## Ursa major (Sep 15, 2009)

Granfalloon said:


> What about our galaxy? Is it just sitting still waiting to be collided into by some big bully named Andromeda?


 
No: your calculations assume constant velocity; you need to factor in acceleration due to the gravitational attraction between Andromeda and the Milky Way. (I'm sure there are other things to consider as well.)


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## Fried Egg (Sep 15, 2009)

Right, I'm getting on the next space rocket out of here...


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## matt-browne-sfw (Sep 15, 2009)

Hasn't the Federation outlawed cannibalism? Oh wait, the Prime Directive. Let's not mess Andromeda's natural course of development.


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