• Question: What type of force would there be if there two galaxies collided?

    Asked by {^-^._.-.-}ALsHmeXi{-.-._.^-^}TGS to Jillian on 17 Jun 2015.
    • Photo: Jillian Scudder

      Jillian Scudder answered on 17 Jun 2015:

      The main force that drives the collision is just plain old gravity! The fact that there are two galaxies behaves sort of like the moon does to our planet, but even more extreme. So, like the water gets stretched towards the moon, the stars and gas in a galaxy get stretched out towards the other galaxy. If they collide face to face (very rare), then you also get shock waves within the gas, because that’s a pretty hard collision – like belly-flopping into a pool. But the vast majority of what happens within the galaxy is due to the impact of gravity!

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