0 a dwarf planet that is farther away from the sun than Neptune, and is the second largest dwarf planet in the solar system --
1 a large, round mass of matter ninth in order of distance from the sun, after Neptune, considered in the past to be a planet --
The spacecraft are now past Pluto and out of the heliosphere – the area around the Sun.
Astronomers, the scientists who study space and planets, decided that Pluto was too small and too far away from our sun to be called a planet.
