Free Astronomy Magazine January-February 2016

7 JANUARY-FEBRUARY 2016 PLANETOLOGY and cratered surface billions of years old (left side), and the almost immaculate smooth stretch of ice, whose age is prob- ably less than 10 million years old; a sure sign of a geologically alive planet, per- haps even in our days. The framed scene is about 530 km across and the smaller recognizable structures reach about 250 metres in width. On the top and side, we instead see the evidence of another surprising discovery made on Pluto, two giant elevations ex- tending as far as 150 km, at the top of which there is a depression that reveals its likely volcanic nature. In the case in point,