EVANSTON, Ill. — Except for the fact that we call it home, for centuries astronomers didn’t have any particular reason to believe that our solar system was anything special in the universe. But, ...

Across the galaxy, astronomers now see that planetary systems fall into four broad classes, and our own solar system, part of the rare Ordered group, is only one of them. At the same time, discoveries ...

The shape of a planet's orbit is one of its fundamental properties, along with its size and distance from its host star.

Astronomers have been searching for evidence that Planet Nine exists for years Becca Longmire is a digital news writer-reporter at PEOPLE. She has been working at PEOPLE since 2024. Her work has ...

There have been questions about a mysterious ninth planet in our solar system for nearly a decade. Pluto was unseated as number nine in 2006. Now, a group of international researchers say they may ...

Discover which planet is the fastest in the solar system. Learn why Mercury moves at 47 km/s, has the shortest year, and ...

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 ...

Jupiter is already the biggest planet by far in our solar system, but new research suggests it was somehow once even larger than it is now. Twice as large, in fact. To put that into context, those ...