Dwarf planets

NASA's Dawn spacecraft has lost another orientation-maintaining reaction wheel, but the failure doesn't threaten the probe's continuing work at the dwarf planet Ceres, agency officials said.

New observations reveal that the far-flung object 2014 UZ224 (informally known as DeeDee, for "Distant Dwarf") is about 395 miles (635 kilometers) wide — big enough to claim "dwarf planet" status.

The only mountain on Ceres may slowly disappear over a few hundred million years, spreading out like honey on a plate.

Pluto's status as a "dwarf planet" is once again stirring debate. This comes as some planetary scientists are trying to have Pluto reclassified as a planet – a wish that's not likely to come true.

The location of newfound water-ice deposits on Ceres are linked to wild swings in the dwarf planet's tilt over the eons, a new study suggests.

On the dwarf planet Ceres, volcanoes rage — but instead of hot lava coming out of them as on Earth, they spew brine and ice.

NASA's Dawn spacecraft has spotted organic molecules — the carbon-containing building blocks of life — on Ceres for the first time, a new study reports.

NASA's New Horizons spacecraft flew past Pluto in the July 2015, snapping several photos of the dwarf planet and its giant, heart-shaped geographical feature.

The dwarf planet Ceres may once have harbored many ice volcanoes, all but one of which have flattened out and vanished into the dwarf planet's surface, a new study suggests.