When Did Pluto Become a Dwarf Planet?

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Pluto became a dwarf planet in 2006. Upon being stripped of its title as a planet, Pluto joined two other celestial bodies, called Eris and Ceres, in the category of dwarf planets. The decision to reclassify the former planet was made by the International Astronomical Union (IAU).

Dwarf planets are much the same as their larger cousins; they share the same physical and chemical compositions and go through the same life processes, from formation through maturity and eventually death. However, according to National Geographic, the primary difference between dwarf planets and regular planets is that dwarf planets do not “clear the neighborhood” around their orbits. This means that they never become gravitationally dominant, and share their orbital spaces with celestial bodies of similar sizes. Pluto classifies as a dwarf planet because it shadows Neptune, the closest regular planet, in its orbital path around the sun. Pluto also journeys around the sun with its moon, Charon, which is similar in size to Pluto. Although the orbital path of Pluto varies in diameter, the dwarf planet averages a distance of 3.7 billion miles from the sun. Given this great distance, Pluto’s surface is permanently frozen, and the small planet’s average temperature is roughly -365 degrees Fahrenheit.