Free Astronomy Magazine September-October 2015

8 SEPTEMBER-OCTOBER 2015 PLANETOLOGY Always on 11 July, the spacecraft turns its instruments also on Charon, showing a surface pockmarked with chasms and cra- ters, of which, among the first, the largest to be framed lies in the southern hemi- sphere and it is longer and deeper than our Grand Canyon. It is the first hint of the disintegration processes affecting the satellite’s surface. The largest of the visible craters is instead a hundred kilometres across and its bright ejecta suggest that it must have formed over the last billion years. The crater’s dark floor may indicate that it is composed of a different type of ice than that of the surface, or that the ice at its bot- 13 July, the LORRI in- strument takes the most beauti- ful image of Plu- to’s globe. [NASA/ Johns Hopkins University Applied Physics Laborato- ry/Southwest Re- search Institute]