There are lots of other planets circling other stars. They discovered a whole new solar system with one telescope. At first it didn't work until a lot of astronauts went up and repaired it. I learned about it from the book Boy, Were We Wrong About the Solar System!.
They discovered Neptune before they discovered Pluto. At first they thought there were just seven planets. But then they discovered that Saturn was shifting for no reason. Then they discovered Neptune! A few years later, they discovered Pluto!! After that they discovered a comet that passed every 37 years.
