Pluto is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun.
In the aerospace context, Pluto was discovered in 1930 by Clyde Tombaugh. It is the second closest dwarf planet to the Sun and is located in the Kuiper Belt, a region of the solar system beyond Neptune that is filled with small, icy bodies.
One example of a spacecraft that has studied Pluto is NASA's New Horizons, which conducted a flyby of the dwarf planet in 2015 and sent back detailed images and data about its surface, atmosphere, and moons. Another example is the European Space Agency's (ESA) proposed ARIEL mission, which aims to study the atmosphere of Pluto and other Trans-Neptunian Objects (TNOs) in the Kuiper Belt.