Alan Stern, principal investigator for the New Horizon mission, reveals his biggest surprise so far as the probe closes in on Pluto. (Recorded 12 July 2015.)
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No. 1 New Horizons at Pluto
The long-awaited fly-by of Pluto by the New Horizons spacecraft, on 14 July 2015, was an event 85 years in the making, following Pluto’s discovery by Clyde Tombaugh in 1930. Since then, Pluto has gone from planet to dwarf planet, but despite protestations from the New Horizons team, its reclassification never really changed the mission or the importance of what it would find at Pluto.

Pluto’s close-up, now in colour
This enhanced colour mosaic combines some of the sharpest views of Pluto that NASA’s New Horizons spacecraft obtained during its 14 July flyby, revealing features smaller than half a city block on the dwarf planet’s surface. The wide variety of cratered, mountainous and glacial terrains seen here gives scientists and the public alike a breathtaking, super-high-resolution colour window into Pluto’s geology.