The small world was found during a search for the hypothetical Planet Nine, and astronomers say the next time it will reach ...

Simulations show that the stars’ tug could send Mercury, Venus or Mars crashing into Earth — or let Jupiter eject our world from the solar system.

Our solar system’s origin story spans billions of years and involves clouds of gas, cosmic collisions, and planetary ...

In the cold, dark outskirts of planetary systems far beyond the reach of the known planets, mysterious gas giants and ...

In April, the scientific world—and the public—was abuzz with the thrilling news that a distant planet called K2-18b might ...

Astronomers have discovered a remarkable planetary system that challenges long-held assumptions about where planets can ...