Pluto Demoted Day is on 24th August, and we are busting out our telescopes to get in the spirit of planetary study! Can you believe that after nearly 80 years as an official planet, Pluto was demoted down to a dwarf planet? The International Astronomical Union (IAU) in 2006 determined that since Pluto is not the dominant object in its orbit around the sun, it could no longer be an official planet.
Other large bodies — like Pluto’s own moon, are found in its region.
History of Pluto Demoted Day
Pluto was discovered in 1930 by astronomer Clyde Tombaugh, making it the ninth planet in our solar system. Pluto is a relatively cold planet that exists outside the orbit of Neptune.
After its discovery, Lowell Observatory had over 1,000 suggestions for what to name the newly found planet. The eventual winner was Pluto, named after the Roman god of the underworld.
In 1992, questions arose around Pluto’s legitimacy as a planet after the discovery of large objects in its region, including one that actually had a larger mass than Pluto itself.
Eventually, in 2006, the International Astronomical Union (IAU) settled on a definition for ‘planet,’ which ultimately excluded Pluto. From that point forward, it has been known as a ‘dwarf planet.’
A dwarf planet is defined as is a celestial body that orbits the sun and has enough mass to assume a nearly round shape but that has not cleared the area around its orbit and is not a moon.
