Clyde Tombaugh was born on February 4th, 1906. In 1930, when he was just 24 years old, he discovered a planet out beyond Neptune, dubbed Planet X. He found it on one of thousands of photographs of starfields, in Gemini the Twins. This constellation is visible in the east after sunset tonight, but Planet X has since wandered off into the other half of the sky, and can now be found in the constellation Sagittarius. After Tombaugh’s discovery, a naming contest was held: the winning entry for the newly found world was Pluto - in mythology, the brother of Jupiter and god of the far-flung underworld. Tombaugh died in 1997, just nine years before the New Horizons probe was launched to Pluto, and the same year – 2006 - that the International Astronomical Union voted to downgrade Pluto to dwarf planet status. New Horizons reached Pluto in July, 2015 and sent back incredible pictures of this distant world, as well as its five moons.