An object eight times the mass of Jupiter may have swooped around the sun, coming superclose to Mars' present-day orbit ...

Though the planets are always “aligned,” seeing more than four in the sky is more uncommon. February’s lineup is a chance to ...

The acid yellow moon Io that orbits Jupiter may be less than 30% the size of Earth, but is considered the most volcanic body ...

The number of planets that orbit the sun depends on what you mean by “planet,” and that’s not so easy to define ...

The formation of our solar system from a singular nebula raises an intriguing question: why did each planet develop with a ...

In a celestial event known as a great alignment the five planets will be discernible with the naked eye, but to see Neptune ...

Stargazers will be treated to a dazzling six-planet "alignment" this January.

NASA’s Juno mission found Io’s biggest volcanic eruption ever. The explosion was stronger than all Earth’s power plants ...

NASA's Juno spacecraft has spotted the most powerful volcanic eruption ever seen on the solar system's most volcanic body, ...

The article humorously imagines how planets would describe themselves if they were dating profiles. Each planet has a unique ...

Simpson and Chen ran mathematical models looking at how differently sized Earth-like worlds would have affected the rest of ...