Pluto, the former planet and the farthest object ever classified as a planet from the Sun, was discovered in February 1930 by a young scientist named Clyde W. Tombaugh. Working for the Lowell Observatory, an organization in Arizona long dedicated to finding the planet, he confirmed many scientists’ hunches. The ninth planet in our solar system, it was also the smallest. Its size would later come to haunt it, as it is actually smaller than our own moon.
Named by a young girl who won an international contest, Pluto became a hotspot for scientific activity in the mid-20th century, as it was too far away for most telescopes to discern. Its dimensions and properties remained a mystery for a long time, with one of its only known characteristics being its moons. Of its five moons, Charon, the largest, is almost as large as Pluto itself. They share a singular point of rotation, like two ballerinas spinning around one point.
Pluto’s status as a planet was cast into doubts by the end of the 20th century, as new discoveries, like its position in the Kuiper Belt, a ring of Pluto-like dwarf planets, and the discovery of Ceres, made leading astronomers define the term “planet”. Unfortunately for Pluto, their guidelines did not include Pluto, and by 2006, Pluto was demoted to a dwarf planet. This was due to its not meeting the International Astronomical Union’s guideline of clearing its own orbit, or namely, Charon. However, many still dispute the decision, and call for its reinstatement as the ninth planet.
In January of 2006, NASA launched a space probe to explore the farthest reaches of our solar system, along with Pluto. Named New Horizons, the probe carried the ashes of Pluto’s discoverer, Clyde W. Tombaugh. On July 14th, 2015, New Horizons passed by Pluto, capturing high resolution photos of the dwarf planet, and helped scientists crack some of the enigmatic planet’s most elusive mysteries.
Although Tombaugh died in 1997, his chance discovery of Pluto, found while staring at before and after photos of the universe, he also discovered many asteroids around Earth’s orbit.
New Horizons is also scheduled to fly past more of the Kuiper Belt’s dwarf planets, many of which remain undiscovered.