Category: insight

Near-true-color image of Pluto taken by New Horizons spacecraft on 13 July 2015. On 14 July 2015, the New Horizons spacecraft became the first spacecraft to flyby Pluto. During its brief flyby, New Horizons made detailed measurements and observations of Pluto and its moons.

Pluto was discovered in 1930 by Clyde Tombaugh, and was originally considered the ninth planet from the Sun. After 1992, its status as a planet fell into question following the discovery of several objects of similar size in the Kuiper belt. In 2005, Eris, which is 27% more massive than Pluto, was discovered, which led the International Astronomical Union (IAU) to define the term “planet” formally for the first time the following year. This definition excluded Pluto and reclassified it as a member of the new “dwarf planet” category (and specifically as a plutoid). Some astronomers believe Pluto should still be considered a planet. (read more)