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

Most planet-forming disks have warps that can lead to planets on inclined orbits, which could explain where the tilt of Earth's orbit came from.

Pluto hasn't been a planet for almost 20 years. In the early 2000s, scientists discovered several objects of a similar size to Pluto. So, during the summer of 2006, members of the International ...

All eight of the solar system’s “major” planets appear in this illustration, but the actual number of planetary bodies orbiting our star is far greater.

Though Pluto has formally been considered a dwarf planet for almost two decades, it still has many lessons left for planetary scientists — including hints about how the solar system formed.

Astronomers using a pair of planet-hunting satellites discovered a solar system with at least six planets rotating around a star in perfect sync with each other.

Astronomers have discovered a brand new type of planet outside our solar system that, even in its infancy, is already bigger ...

Such synchrony may occur when planets first form, but astronomers theorize that as time goes on, its likely for orbits to get knocked out of rhythm.

Astronomers have discovered a rare in-sync solar system with six planets moving like a grand cosmic orchestra, untouched by outside forces since their birth billions of years ago. The find ...