For the first time, astronomers have detected radio signals from a planet beyond our solar system, according to a study ...

A new study suggests that our solar system’s smallest planet has shrunk by up to 30 percent since its birth roughly 4.5 ...

Astronomers found a Neptune-sized planet orbiting backwards around its star, but the usual explanation for its bizarre path is nowhere to be found.

Astronomers have confirmed a world less than a million years old as the youngest known planet, using data from archives.

The solar system's smallest planet has gotten smaller still.

Purple is only the latest entry in Mars’s surprisingly broad color chart.

Astronomers have confirmed a Jupiter-size planet less than a million years old, making Elias 2-24 b the youngest known planet and giving scientists a rare look at a world still being born. Its ...

Two decades ago, Pluto was reclassified as a dwarf planet, sparking an enduring debate. NASA Administrator Jared Isaacman says he wants to “make Pluto a planet again.” ...

Twenty years after Pluto lost its planetary status, the debate continues as scientists still disagree over what defines a planet.

Radio signals detected at a planet beyond our Solar System ...