In 2005 an object larger than Pluto was discovered in the Kuiper Belt. This discovery would call Pluto's planetary status into question and help create a new term, Dwarf Planet.

With a diameter of about 880 miles, the dwarf planet is about two-thirds the size of Pluto—and about three times the size of the 277-mile-long Grand Canyon—making it the 25th largest object in ...

For the better part of a century, we believed there were nine planets in our solar system, with Pluto being the farthest from the sun. Since the discovery of more Pluto-sized dwarf planets, that ...

On Friday morning (March 6), NASA's Dawn spacecraft will arrive at Ceres, becoming the first probe ever to orbit a dwarf planet. Ceres is the largest object in the asteroid belt between Mars and ...

With the help of computer simulations, this dwarf planet's history may reveal clues about icy worlds in the solar system.

A dwarf planet called 50000 Quaoar that orbits beyond Neptune appears to have a ring that shouldn't be there, at 7.4 times more distant than the planet's radius.

In terms of sheer weirdness, few objects in the solar system can compete with the dwarf planet Haumea. It has a strange shape, unusual brightness, two moons, and a wild rotation. Its unique ...

Seven interesting facts about the dwarf planet Ceres, which NASA's Dawn spacecraft will begin orbiting on Friday (March 6).