"Rings are mostly made of ice and small rocks," said William Saunders, a planetary scientist at NASA's Langley Research Center. "Saturn's are mostly ice, Jupiter's are mostly dust, and Uranus' and ...

Today, it’s believed that Jupiter and Saturn, the largest planets, were the first to fully form, both within a few million ...

Astronomers find evidence of a possible ninth planet beyond Neptune, reigniting the debate about the formation of the Solar ...

U.S. astronomers hunting for "Planet Nine" have instead stumbled on what appears to be a new dwarf planet in the solar system's outer reaches.

Scientists' hunt for a mysterious planet at the edge of our solar system might have turned up results. A US-trio appears to ...