Free Astronomy Magazine September-October 2015

6 SEPTEMBER-OCTOBER 2015 PLANETOLOGY bodies, definitely not common in that desolate part of our sys- tem. Pluto has instead turned out to be a remarkably diversified (dwarf) planet, with an atmosphere more similar to that of Earth’s in terms of nitrogen con- tent percentage, but, above all, to be geo- logically active. Evidence of this unexpected fact first emerged from a picture of Pluto taken on 9 July by the Long Range Reconnaissance Imager (LORRI) of New Horizons, when the spacecraft was still 5.4 million km from the planet, after having already travelled more than 5 billion km in 9 and a half years. With a resolution of 27 km/pixel, this image allows to observe details barely hinted in the previous days’ recordings: the surface appears very varied, with large areas of different albedo and diverse cra- tering levels. The surface structure more 11 July, the sur- faces of Plu- to (above) and Charon (below) clearly reveal the presence of cra- ters, chasms and troughs. [NASA/ Johns Hopkins University Ap- plied Physics Lab- oratory/South- west Research Institute]