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I’ve been to Pluto

Clyde Tombaugh discovered Pluto in 1930 when he was 24, and was working at the Lowell Observatory in Flagstaff, Arizona. Pluto was a planet until 2006, when the International Astronomical Union finally defined what a planet was (“a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit”), which excluded Pluto from the definition. As it doesn’t meet the third criterion, Pluto is a “dwarf planet”.

Tombaugh died in 1997 and his ashes are on board the New Horizons spacecraft, now more than four billion miles from Earth, and are headed beyond his dwarf planet to Ultima Thule, which it will be flying past on 1 January 2019.

Picture source: NASA