Beyond the familiar planets lies a fascinating frontier filled with icy worlds, mysterious orbits, and cosmic curiosities.

Astronomers propose a new hypothetical planet, Planet Y, beyond Neptune, based on observed orbital anomalies in the Kuiper ...

On Aug. 24, 2006, the International Astronomical Union (IAU) decided that Pluto wasn't a planet anymore. Instead, Pluto is ...

Radioactive decay produced a warm internal ocean Dwarf planet Ceres, the unpleasant lump of icy rock orbiting between Mars ...

In 2006, and after much debate, the International Astronomical Union came up with a new definition for a planet. And for the first time, the term "dwarf planet" was used. Dwarf Planets ...

In Roman mythology, Pluto is the god and ruler of the dead. For a return mission to the dwarf planet, Howett and her ...

Astronomers discover GJ 2126 b, a giant planet with an extremely eccentric orbit, 124 light-years away, using HARPS data.

The waning Moon passes Jupiter, Venus, and Mercury before dawn, while Titan’s shadow transits Saturn in the sky this week.

For the first time since 2008, two new planets are being added to one of northern Maine's most famous — and scientifically accurate — roadside attractions. Dwarf planets Haumea and Makemake ...