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.)
Have you ever seen a dwarf planet? Of the five within our solar system recognised by the International Astronomical Union – Ceres, Pluto, Haumea, Makemake and Eris – only Ceres can be considered bright and easy to locate. It reaches opposition in the constellation of Scorpius on 29 May at magnitude +7, an easy binocular object if you follow our guide.