Take a look at this. Watch it a few times...See what you can see.
If you saw one of the dots moving you saw the same thing I did. What is that moving dot you might be thinking...I have the answer. That dot is Pluto, once a fully fledged planet, now just a dwarf planet hanging out in the far outer reaches of the solar system.
The two images were taken almost exactly 24 hours apart. The dots that stay still are stars in the background, and anything which moves is in our solar system. This is one of the ways of finding asteroids and Kuiper belt objects. Take images a day or two apart then flip back and forth between them to see if anything moves.