Pluto is a complex and mysterious icy world located far out in the Kuiper Belt, a ring of icy bodies beyond Neptune. For a long time, it was considered our solar system's ninth planet!
In 2006, scientists reclassified Pluto as a "Dwarf Planet" because it shares its orbital neighborhood with many other icy objects. Even though it is small (it's actually smaller than Earth's Moon!), it is packed with fascinating features.
When the New Horizons spacecraft flew past Pluto in 2015, it revealed a stunning landscape, including mountains made of solid water ice and a massive, heart-shaped glacier made of frozen nitrogen!