Astronomers have observed diverse features and characteristics of Pluto, which include mountains, valleys, and plains on its surface, a notable heart-shaped region named Tombaugh Regio, a delicate atmosphere made up of methane, nitrogen, and carbon monoxide, as well as multiple small moons such as Charon, Nix, Hydra, Kerberos, and Styx. The planet showcases past cryovolcanism geologic activities that involve icy materials, and on its surface, it harbors water ice, nitrogen ice, and different volatile compounds.