Hubble snaps aftermath of galactic pile-up The Hubble Space Telescope has captured an impressive image demonstrating what happens when two spiral galaxies crash into each other at high speed: Galaxy NGC 2623 captured by the Hubble Space Telescope The European Space Agency's Hubble site explains: "Studies have revealed that as galaxies approach one another, massive …
Err, probably not. Unless you lived to be at least a couple hundred thousand of our earth years (I gather that's the time scale of these events), In which case you might notice a good number of stars getting a good bit brighter over time, and the local Milky Way (if yours was a disc galaxy) getting a side street.
I suspect your question is a rhetorical one, but I think it's a fascinating subject so I'm going to throw in my two cents.
I think it would depend where in the galaxy said star system existed, near the edges and you would probably just notice a flurry of new star formation and the possibility of your system being flung out of the galaxy. None of which would matter anyway in human timescales.
Near the centre and you would be looking at the possibility of outer planet orbit anomalies (due to passing larger stars), which in turn can stir up a load of cometary debris and asteroids that dwell in the outer shell of the system which may then start a long journey to the inner solar system - which can be bad news if you live on a particularly unlucky planet.
Apart from that, there is always the risk of colliding black holes which cause Gamma Ray Bursts. I'm sure you know that you don't want to be near one of those when they go off and I'd imagine that when galaxies collide the objects with most mass find each other pretty quick.
There's a chance that a galactic collision could result in another star coming close enough to disturb the orbit of your planet sufficiently to eject it from its own planetary system, but you'd see it coming. Galactic collisions also occur over time scales that far exceed those experienced by humans.
If you hang around for a bit longer you might just see Andromeda collide with the Milky Way. The collision will play out over millions of years, but you'll have waited 3 billion years for it to occur so what's a few million more?
I imagine the sky might get quite interesting, assuming of course that we haven't drowned it out with streetlights...
Although "high speed" wrt galactic collisions is still a pretty slow collision in our timescales.
The paper on the ESA website indicates (after a very brief skim) that many of the "new, young" stars are between 1 and 100 million years old...
For reference our galaxy is ~100,000 light years across, so a pair of milky way's colliding at .9c would still take 60 thousand years to have a "midpoint" collision...
"Just one thing puzzles me: how is it that we see galaxies colliding at these sharp angles? "
Simplistic explanation: the Big Bang starts it all, hurling stuff outwards. Bits of that stuff clump together to form galaxies. Some galaxies get a bit dense and explode, causing Smaller Bangs and hurling stuff outward *from that point*. If you have two galaxies on different radials from the Big Bang do that, they may well throw stuff right at each other.
Great image
A big factor is really whether the galaxies have an active or inactive black hole in the middle. ours is inactive as is andromeda so when we crash we wont notice. The chances of a 3 body inteaction with another star is so remote thats its virtually zero.
The problem is really about dust and gas. although its near vaccum densities , there is a lot of it...an awful lot. If gas clouds become gravitationally linked it will compress untill...like our sun ...it goes supernova and greates a new star.
If you are within a few million light years , you are in for a very bad day . Gamma ray bursts from the explosion will destroy pretty much everything organic at high levels. You'll get a nice suntan for a few milliseconds then you're toast.
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