Can asteroids come from other galaxies?

In theory,yes. But then the asteroid would have to somehow get ejected from its solar system AND its galaxy (which would require a truly catastrphic event), travel the gazillions of miles to the other galaxy and eventually enter another solar system. This is very unlikely.

There is nothing that forbids an asteroid from drifting and joining another galaxy, but gravity says that this is extraordinarily unlikely.

The reason for this is that asteroids would be formed though the condensation of space dust and gas in an emerging solar system somewhere. For an asteroid to leave its solar system, something would have to push it away. There are few things that can propel an asteroid to a speed high enough to escape the gravity of a whole galaxy *without* blowing it up, but even if one was to find a supernova that would oblige, the asteroid would have to careen through our galaxy at the same speed it left its original one, and that essentially means 'no stopping', An asteroid from another galaxy would just speed though ours and end up leaving it as well.

The only mechanism one can think of that would actually make matter from another galaxy join ours is if the galaxy interacts with ours (collision, merging, or our galaxy 'swallowing' a smaller one that wandered too close). Those events are rare, but in such circumstances, the asteroids would remain bound to its original star, the whole star system would be joining a new galaxy.

Where Does Asteroids Come From

Very unlikely. All the asteroids we know of are in stable orbits around the Sun, and were formed in our own Solar System at the same time as the Sun and planets. There's a remote possibility that a few may have come from neighbouring star systems, but zero that they come from other galaxies. Do you realize just how far away other galaxies are?

Highly unlikely but not impossible

Galaxies are many millions of light years away so there has not been enough time to cross that distance since the universe began.

Also the gravity field of a galaxy is enormous.

Ant asteroid ejected from a galaxy will probably travel for a million years then turn round and go back

The probability for an asteroid or two from a Planetary system of a Star located a dozen Parsecs from us to somehow reach our system, dodging all those huge gravitational bodies (massive stars mostly) on its way, is too too low. For that the Asteroid must acquire to possess an incredibly high velocity.

Even with that almost zero-like probability, what with the trillions of chunks from the space debris, one might reach us in a ten or twenty thousand years.

Remember ! Our star, the Sun doesn't have such a heavy-weight stellar role to attract these passing chunks.

First ask where our system's asteroids came from.

Theory has it that the solar system condensed from a vast cloud of dust and gas that drifted along until shocked by a supernova or stellar winds and collapsed under it's own gravity.This Gass is primarily hydrogen left over from the big bang itself but it's full of dust created in the deaths of first generation stars.All the element we know exist naturaly were there, created in the supernovas of the first gint stars and possibly many others.

Eventualy the sun lit up and fierce solar winds many thousands of times as intense as today,raked all the light weight gass away to the outer solar system to form the gas giants.The heavier dust and debris stayed in close and congealed over many trillions of collisions into the rocky planets we have today.

The "Asteroid Belt" is a bad gravity zone between the orbits of Mars and Jupiter so it kept the bits and pieces bumping around and moving to fast to condense into a planet.That process is still ongoing.

As Jupiter and Mars flow along in their orbits,the asteroids slide toward them just a bit. So the asteroids are always doing "The Wave" as these two planets pass them.When the two planets are directly across the asteroid plane from each other the two planets gravities battle each other and all this adds up to constantly disturbing the asteroids otherwise peacefull orbits.

They bump around and change course and sometimes get tossed out of the belt alltogether and start "wandering" around the solar system.When they wander they always wander toward the sun unless they are lucky enough to catch a gravity boost from a moon or planet and get into a somewhat circular orbit. Others will crash into the planets and moons or the sun itself.

Gravity whips from jupiter and it's moons could potentialy eject an asteroid from the solarsystem but it would be a real longshot since most asteroids are below jupiter in the gravity well.To get on out far enough for jupiter to grab it it would have to do a real fast and realy close run at the sun and miss,likely also picking up a gravity boost from venus or earth.

To get one out of the galaxy would likely take a supernova.But then it would be ejecta and not asteroidal.

The distance is so large between galaxies it's unlikely an asteroid could have crossed the distance from the nearest in this way. It would take a huge amount of gravity boosts to get up to cosmologicly practical speeds.

Voyager two, the grand tour Probe launched in the seventies used gravity boosts from Jupiter Saturn to gain and escape velocity to leave the solar system.I't going over three times the distance from Earth to Sun every year.It's still not out of our solar system. 93,000,000x3.3 per year.It will never leave the galaxy.Likely it will fall into a very long eliptical orbit and eventualy fall back toward the Sun.

There is nothing in theory that prevents it. But insofar as asteroids are products of the formation of solar systems, it is more likely that they will remain within the gravitational influence of their parent stars rather than drifting in the deep space between stars or, even less likely, the far deeper space between galaxies.

Probably not in this solar system. It may be the case that asteroids are hurtling between galaxies somewhere else but so far scientists only know so far as our solar system and the asteroid belt.

I was a bit late getting here, but Lordy lordy.....Asteroids are possibly the best exlample of "other places" I refuse to correct my spelling 'cos as I'm busy with off worldly stuff at the present. Print pages while I'm gone. I know where I am.