Though Pluto has formally been considered a dwarf planet for almost two decades, it still has many lessons left for planetary scientists — including hints about how the solar system formed.

The dwarf planet also has one provisional moon, which is nicknamed MK 2. Discovery: March 31, 2005. Size: 888 miles in diameter (1/9 the size of Earth) Distance from sun: 4.3 billion miles.

Dwarf planets are smaller planets that do not meet all three categories of a planet. According to NASA, they are round in shape and orbit the sun, but don’t clear their orbital path.

For the dwarf planet candidate, one trip around the sun takes over 24,000 years. Its orbit challenges a proposed path for a hypothetical Planet Nine.

With this structure, the dwarf planet would get gradually muddier and less frozen at lower depths. A NASA spacecraft got a closer look at Ceres' surface between 2015 and 2018 through the ...

The ring in question orbits Quaoar, a small dwarf planet that lies more than 4 billion miles from the sun—roughly 44 times the distance between Earth and our star.

All 19 detections of the dwarf planet 2017 OF201, from August 2011 to October 2018. Credit... Cheng et al., arxiv.org, 2025 ...