Astronomers say they have evidence that there may be a hidden planet in our Solar System. Named 'Planet Y', the Earth-sized ...

Think you know Pluto? From icy plains to planetary debates, this quiz dives deep into the mysteries of our solar system’s most controversial—and captivating—dwarf planet.

A new face has been added to the solar system's family portrait: Scientists have discovered a new dwarf planet looping around the sun in the region beyond Pluto.

The Solar System has a new most-distant member, bringing its outer frontier into focus. New work from Carnegie’s Scott Sheppard and Chadwick Trujillo of the Gemini Observatory reports the ...

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

For three-quarters of a century, schoolkids learned that our solar system has nine planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.

Unnamed Dwarf Planet is the first to get its name after a Chinese Water God, calling it Gonggong, which is a creature from Chinese folklore. Find out more here.