In an article posted by Space.com (https://www.space.com/galaxies-collide-and-warp-hubble-image.html) Hubble releases a new image of the aftermath of a near galactic collision. The galaxies involved, NGC 4485 and NGC 4490 (not pictured), passed near by one another and as a result the larger combined gravity of NGC 4490 caused a stream of gas and stars to be ripped away from NGC 4485 and the galaxy to become significantly warped. This stream of gasses and stars made me wonder, what if there were life on a planet orbiting one of those stars? What would they see?
The stars we see in our own night sky, for the most part, are members of our own galaxy. We can see other galaxies in our night sky if you have a powerful enough telescope but the large part of the things we see are in our (relative) backyard. What would lifeforms on those stars stretched between NGC 4485 and NGC 4490 see? Would their night sky be more black than ours? Would they see more galaxies than we can see? One of the prime issues we can’t see many galaxies with small telescopes is because of all the light coming from other stars blocking them out, as well as our own industrial light pollution.
I imagine that would be a beautiful sight seeing the stars around your home star being pulled into another galaxy but beyond those relatively close stars the empty ocean of space opening up for you to see. What would their scientists think? Would they realize that they are victims of a near collision of galactic proportions? Would they have better insight into the laws of gravity and relativity then we have had? Would they reach the same conclusions as we have about the universe? Would they be able to see more of it as a result of being outside their home galaxy?
What would the night sky look like for a planet orbiting a star that was flung from it’s home galaxy and is adrift in the deep ocean of space? With no neighboring stars what would they see? Would they have a night sky full of galaxies the way ours is full or stars? Would their nearby galaxies take up most of their viewing? How would their scientific exploration of the universe differ from our own?
We know that in a few billion years, long after the earth is gone and our star is a white dwarf, that our galaxy and the Andromeda galaxy will collide. Not a near miss, not a graze, not a gentle nudge, but a full blown head-on collision. Based on models of this collision we can assume that several stars will be thrown from both galaxies. What will life be witness to during that collision? Will there be descendants of humans around to see it really begin? I hope so. I hope our spices evolves and is able to become interstellar and eventually intergalactic and has the best seats in the house to watch the collision and the combining of two super-massive blackholes. I imagine that will be a beautiful and terrifying sight to see.