Snapchat Planets turns your friendship ranking into a tiny social solar system, where being Mercury is elite and Neptune ...

The Solar System is far more diverse in size than it appears from Earth. From tiny rocky worlds to massive gas giants, each ...

CAPE CANAVERAL, Fla. — Astronomers have discovered a rare solar system in the Milky Way that boasts six planets orbiting in perfect rhythm like a cosmic orchestra, untouched by outside forces since ...

Some researchers see in this population the manifestation of an invisible presence, a new planet not yet discovered in the dark and cold confines of our solar system. Others, however, think that there ...

The rusty world is full of mysteries—and some of the solar system's most extreme geology. Learn more about Earth's smaller, colder neighbor.

It's an evocative idea that has long bedeviled scientists: a huge and mysterious planet is lurking in the darkness at the edge of our solar system, evading all our efforts to spot it. Some astronomers ...

On August 24, 2006, our solar system lost a planet. It wasn't by cataclysmic destruction, but rather by the vote of the International Astronomical Union, which declared that Pluto, considered the ...

In context: The Oort cloud is a cloud-like structure that scientists believe surrounds the Solar System, essentially behaving like the outermost limit of the Sun's gravitational influence in the Milky ...

There may be another world lurking between the orbital lines of our solar system. Astronomers in Japan have published their theory of an “Earth-like planet,” dubbed Planet Nine, that’s hiding in plain ...