For 70 years, Pluto was considered the tiniest and most distant planet in our solar system. And many still classify it that way. But new discoveries of Pluto-like worlds—smaller and farther out—have caused some astronomers to rethink how they think about Pluto.

In 2006 the IAU reclassified it—and its siblings out there—as a dwarf planet.

No matter how you classify it, this icy and remote outpost is an odd little world. Its size, composition, moon, and orbit place it in a class by itself compared to the other planetary-mass objects.

From its surface, the sun is a mere point of light only 250 times brighter than the moon. A year on Pluto is the equivalent of 248 years on Earth.