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  • It might be odd to get your head around, but galaxies can and do collide.

  • But far from an wild party of death, galaxies collisions yield hotbeds for new star formation,

  • leading astronomers to suspect that this not-so-violent event is actually a driving factor behind galactic evolution.

  • The big question here is how can galaxies collide and not just destroy everything?

  • It helps to think about what a galaxy really is.

  • Every galaxy is made up of some 100 billion stars with planets orbiting their host stars,

  • but those stars are really far apart.

  • Take the Milky Way for example.

  • We're about here on the edge of a spiral arm called Orion Spur.

  • It looks crowded in our little neighborhood, but our nearest neighbor Alpha Centuri A, is actually 4.3 light years away.

  • So galaxies might full of stars, but those stars are really far apart, meaning the likelihood of two hitting is pretty low.

  • But that doesn't mean nothing happens, because there is stuff in those vast distances.

  • Thespacebetween stars is actually full of gas and dust.

  • Within these regions are dense pockets of interstellar material, called molecular clouds,

  • that collapse under their own mass and gravity, forming protostars and eventually new stars.

  • When galaxies collide, it's this materialthe interstellar gas and dustthat

  • interacts gravitationally with some neat results.

  • In a collision, one galaxy can rip material from another, disrupting star formation and

  • adding more material to its own molecular clouds.

  • A direct collision between these gases can also result in shockwaves reverberating through

  • both galaxies, triggering new regions of star formation where there wasn't any before.

  • Aside from generating new pockets of star formation, both close passes and full-on collisions

  • cause gravitational interactions begetting interesting changes, causing spiral arms, tidal tails, and even rings.

  • Two spiral galaxies could merge and form an elliptical galaxy with more active star formation than either had before.

  • But it's not like this happens overnightnot that there's a “nightwhere galaxies are concerned.

  • This process can take millions of years.

  • Which is a good thing because our own Milky Way is on a crash course with the Andromeda galaxy, but we've got a good 4 billion years

  • That should be enough time to live my best life.

  • If you want more cosmic science in your feed be sure to subscribe to Seeker.

  • And if you want to know what happens when galaxies die, Trace has more on that right here.

  • You know what'd be awesome?

  • If after the Andromeda collision our sky lit up with tons of newly forming stars!

It might be odd to get your head around, but galaxies can and do collide.

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What Really Happens When Galaxies Collide

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    Jerry Liu posted on 2019/05/14
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