Dwarf Planets
Intriguing Worlds of the Outer Solar System
Dwarf planets are celestial bodies that orbit the Sun and are massive enough to be round, but have not cleared their orbital path of other debris. The most famous dwarf planet is Pluto, which was reclassified from planet status in 2006.
Officially Recognized Dwarf Planets
- Pluto: Largest known dwarf planet, located in the Kuiper Belt
- Eris: Slightly smaller than Pluto, more massive
- Haumea: Egg-shaped due to rapid rotation
- Makemake: Cold, distant world in the Kuiper Belt
- Ceres: Largest object in the asteroid belt
Pluto's Demotion
In 2006, the International Astronomical Union reclassified Pluto as a dwarf planet because it had not "cleared its neighborhood" of other objects. Despite this, Pluto remains a fascinating world with mountains, glaciers, and a thin atmosphere.
New Horizons Mission
NASA's New Horizons spacecraft flew past Pluto in July 2015, revealing a complex world with a heart-shaped nitrogen glacier, ice mountains, and evidence of a subsurface ocean. It was the first spacecraft to visit Pluto.