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wowsosquare t1_j99cnp1 wrote

Reply to comment by Davicho77 in The Tadpole galaxy by Hubble, Its eye-catching tail is about 280,000 light-years long. Also known as UGC 10214 and Arp 188, it is a disrupted barred spiral galaxy located 420 million light-years from Earth in the northern constellation Draco. Credit Image: NASA/ESA/HST/STScI. by Davicho77

>When two galaxies come close to each other...

I thought this was going to be The Talk about when the Mommy galaxy and the Daddy galaxy give each other a very special hug. Was disappoint.

THAT SAID, when galaxies collide, how does it effect what's happening on a any given planet or solar system in the colliding galaxies? Because for the most part everything just zips right past everything else, right? There's very little matter actually colliding

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Kossimer t1_j99xp0w wrote

Right, almost no matter at all collides. The biggest change any star system may find is being ejected from its galaxy, but everything inside the star system keeps orbiting as normal, the planets around the star don't mind. Star formation may be invigorated by colliding and collapsing dust clouds. If life exists on a planet in a colliding galaxy, the other galaxy looming large in the sky would make observation and science virtually impossible for any part of space behind it.

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wowsosquare t1_j99y89i wrote

What about all the dust and hydrogen that's in the interstellar medium and maybe More dense in solar aysi... could the relative speeds of colliding galaxies give you all those dangerous effects of traveling at high speeds?

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Kossimer t1_j9bhim2 wrote

The interstellar medium is less dense outside of galaxies, but it's already very sparse and it doesn't do much. It makes no difference to a star system that might be outside of a galaxy.

A star would have to make a near pass with a black hole or a neutron star to be slingshot into relativistic speeds, which almost certainly would not happen to a single star in a galaxy collision, statistically speaking. A star does not need to travel nearly the speed of light to escape a galaxy, but stars also almost never escape anyway because galactic collisions are so rare and are one of the few events capable of doing it. More likely, a star that escapes a galaxy is somewhere in a tail of matter being pulled away slowly from its home galaxy via a collision like pictured in the post, in a small chunk that the galaxy's gravity never recaptures.

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