Guest star (astronomy)

In astronomy, a guest star is when we see something new and bright in the sky that wasn't there before. It's kind of like when you go out in your backyard and see a shooting star – it's something you don't usually see and it's really exciting!

Guest stars usually happen when a star explodes in a big, bright burst known as a supernova. This makes the star shine really brightly for a short period of time, sometimes even as bright as an entire galaxy full of stars!

Scientists study guest stars to learn more about how stars are born, live, and die. They can also use guest stars to help figure out how old the universe is and what it was like in the past.

So, a guest star is like a special visitor in the sky that scientists study to learn more about the universe.