In the cold, dark outskirts of planetary systems far beyond the reach of the known planets, mysterious gas giants and planetary masses silently orbit their stars—sometimes thousands of astronomical ...

Astronomers have found thousands of exoplanets around single stars, but few around binary stars—even though both types of stars are equally common. Physicists can now explain the dearth.

A planet circling at a sharp 90-degree angle to the orbits of its two host stars has now been confirmed. This discovery challenges long-standing ideas about how planets form and orbit in the cosmos.

There could be a ninth planet in our Solar System after all - and no, it's not Pluto. Instead, it's the theoretical Planet X, also called Planet Nine, a wide-orbit planet that would circle the Sun ...

The small world was found during a search for the hypothetical Planet Nine, and astronomers say the next time it will reach its closest point to the sun is in the year 26186. By Kenneth Chang Kenneth ...