The Hubble Space Telescope has peered at Uranus, left, and Neptune to study the so-called "ice giant" planets, but little is known about their interior composition. - NASA / ESA / M. Showalter / L.

We actually know very little about what's going on inside Uranus and Neptune, causing researchers to propose that these ...

For generations, school posters have sorted the Solar System into tidy boxes: four small rocky planets near the Sun, two huge gas planets farther out, and, at the edge, a pair of “ice giants” – Uranus ...

Add Yahoo as a preferred source to see more of our stories on Google. When you buy through links on our articles, Future and its syndication partners may earn a commission. Neptune (left) and Uranus ...

A team of researchers is challenging our understanding of the Solar System planets interior. The composition of Uranus and Neptune, the two outer most planets, might be more rocky and less icy than ...

So, it came as a shock to many people when, in 1781, it was announced that a seventh planet, the first to be discovered since ...

The planets in the Solar System are typically divided into three categories based on their composition: the four terrestrial rocky planets (Mercury, Venus, Earth and Mars), followed by the two gas ...