Clyde Tombaugh began searching for a ninth planet in 1929 and stumbled upon Pluto the following year. In the decades since, our view of Pluto hasn’t changed much. All of that changes on July 14 when the New Horizons spacecraft, nearly 5 billion kilometers from home, slipped past Pluto and gave humankind its only look at this icy world (see "Rendezvous with Pluto," SN: 6/27/15, p. 16). Below are several milestones leading up to the 2015 Pluto flyby.
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