OBSERVING Celestial Calendar Pluto Has the Last Laugh For a non-planet, Pluto sure shows some amazing planetary traits. Ten years after being downgraded from Ninth Planet to "dwarf planet" and "just a large Kuiper Belt object" (yes, for good reasons), Pluto can laugh in astronomers' faces. The New Horizons flyby a year ago - data are still trickling back through the spacecraft's slow link - has revealed that this supposedly dead ice-asteroid beats some of our favorite planets at their own game. Pluto is more geologically active than Mercury or Mars, sporting a giant, recently formed plain of upwelling frozen nitrogen. Unlike Mercury, Pluto has a thin but significant atmosphere. The atmosphere displays some 20 scenic layers of haze at high altitudes, and lowlying hazes as well that give sunset landscapes an eerily Multifarious Pluto, in exaggerated color. NASA / JHUAPL / SWRI 19h 13m 17 21 19h 12m 25 29 June 2 -21° 6 10 19h 09m 19h 10m 19h 11m 19h 0 / 14 18 22 26 30 July 4 8 12 SAGITTARIUS -21°15' -21°30' -21°45' 48 July 2016 sky & telescope