Astronomers have found a distant world that challenges planetary formation theory, with a rocky planet where gas giants should be.

Our solar system is a smashing success. A new study suggests that from its earliest period — even before the last of its nebular gas had been consumed — Earth’s solar system and its planets looked ...

A small red dwarf star in the Milky Way has drawn attention after astronomers mapped four closely orbiting planets around it.

Deep in the older, denser reaches of the Milky Way, there is a red dwarf star that shouldn’t exist — or at least, its family ...

The search for an unknown planet in our solar system has inspired astronomers for more than a century. Now, a recent study suggests a potential new candidate, which the paper’s authors have dubbed ...