Dwarf Planets

NASA is facing a plutonium shortage that may thwart future missions.

The Department of Energy has made its first plutonium-238 in a quarter century.

A rare type of plutonium has been found in the crust below the deep sea, offering new clues as to how heavy metals form in star explosions and mergers.

Strange hexagonal diamonds may have been jettisoned into space when a dwarf planet collided with a large asteroid around 4.5 billion years ago.

A new model exploring the dwarf planet Ceres suggests radioactivity deep in the small world may have created criss-crossed geology at its surface.

A new computer simulation suggests that dwarf planet Ceres may have been flung by the gravity of gas giant Jupiter into the asteroid belt during the volatile era of planet formation.

In 2006, and after much debate, the International Astronomical Union came up with a new definition for a planet. And for the first time, the term "dwarf planet" was used.