The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define ...

Our Solar System is simple—one star, planets orbiting around it. But what happens in a system with multiple stars? Scientists ...

Stargazers will be treated to a rare seven-planet alignment in February. This is what scientists hope to learn.

Worlds with liquid water could have formed just 200 million years after the big bang from the remains of the earliest ...