Pluto is so small that it's actually smaller than Earth's own Moon, yet it carries one of the most recognizable features in the solar system: a giant, heart-shaped glacier made of nitrogen and carbon monoxide ice, informally named Tombaugh Regio.
Pluto and its largest moon, Charon, are so close in size that they don't quite orbit like a normal planet-and-moon pair — instead, they both circle a shared point in empty space between them, locked together in a gravitational dance as a true binary system.