When we look up at the night sky, each twinkling dot looks like a single star. Many of them aren’t. Astronomers now know that more than half of all sun-like and bigger stars come in pairs or larger groups. Two stars orbiting each other are called a binary system. Three or four together are called triple or quadruple systems. A few systems have five, six, even seven stars all bound together by gravity. (The most common stars in the galaxy, tiny red dwarfs, are mostly single - so if you count every star, more than half are loners.)
The reason most stars come in groups is that they form together. When a giant cloud of gas collapses to make stars, it usually breaks up into several lumps, each one becoming its own star. They end up locked into orbit around each other from the beginning.
Our Sun is one of the lonely exceptions - a single star, no companion. That used to be considered normal, but new surveys keep finding more multi-star systems out there. Star Wars style planets with two sunsets aren’t science fiction; they exist for real, orbiting binary stars across the galaxy.
