Our solar system has two ice giants, Uranus and Neptune, but there may have been a third. According to a new study published ...

Astronomers are closing in on one of the most tantalizing possibilities in planetary science, evidence that a previously unknown world may be lurking in the outer reaches of the solar system. The ...

New research suggests the moons of Jupiter and Uranus may hint that our planetary neighborhood once had a third ice giant.

There's a new object in the distant reaches of our solar system, and it might just offer clues to a long-standing cosmic mystery. Astronomers have cataloged a frozen minor planet called 2017 OF201, ...

An artist's impression of the planetary system surrounding LHS 1903, a small red dwarf star cooler and dimmer than our Sun. (European Space Agency) (CN) — For decades, astronomers thought they had ...

Scientists have discovered a bizarre planetary system where a rocky world orbits farther out than giant gas planets, defying ...

What can rocky planets orbiting in the outer parts of a solar system teach scientists about planetary formation and evolution? This is what a recent study published in Science hopes to address as a ...

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 ...

A NASA Hubble Space Telescope observation program called OPAL (Outer Planet Atmospheres Legacy) obtains long-term baseline observations of Jupiter, Saturn, Uranus, and Neptune in order to understand ...