As (hopefully) a future astrophysicist, I have some pretty coolness about this for you

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It's called gravitational lensing. Light is affected by gravity. So when a source of big gravity (like a black hole or a solar system) is in between the earth's telescopes and a source of light (like another solar system), the light of this solar system that is sent out is bended by the gravity into our telescopes, creating the illusion of a bunch of solar systems around the gravitational field. Of course those solar systems aren't there and are just reflections of the 1 solar system behind the source of gravity.
Clarification:
The grey arrows are the actual paths the light follows, whereas the orange ones are what we appear to see

None of those blue solar systems are there, they're all reflectations of 1 solar system behind the larger yellow one

This is the most famous one, Einstein discovered the phenomenon and this was the 1st time it was observed

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