Pluto was discovered on this day in 1930 by American astronomer Clyde Tombaugh. Millions of American children grew up learning Pluto as our solar system's distant ninth planet until it was downgraded to a dwarf planet in August 2006 by the International Astronomical Union. Swipe through to learn more about Pluto and why it's no longer considered a planet. We have more about dwarf planets from Dornsife Physics and Astronomy Professor Vahe Peroomian at the link in our bio. 📸: nasa, Creative Commons #Pluto #PlutoDay #SolarSystem #Space #Planets #DwarfPlanet