Free Astronomy Magazine September-October 2015

7 SEPTEMBER-OCTOBER 2015 PLANETOLOGY markedly visible in this image is a long dark region lying on the equator, provisionally called “whale” due to its odd shape. Of partic- ular scientific inter- est immediately ap- peared the tran- sition territories between the “whale’s tail” and the planet’s western edge, where for the first time were noticed some unusual polygo- nal formations, that in the next 14 July flyby would not be possible to observe in detail, since located in the opposite hemi- sphere to that framed by the spacecraft’s instruments. On 11 July, at a distance of 4 mil- lion km from Pluto, LORRI photographs the hemisphere constantly facing Charon (the one not visible during the flyby) and acquires the best ever picture of 4 large areas, apparently circular and wide nearly 500 km each, all arranged along the equa- tor and adjacent to the “whale”. Already glimpsed during previous recordings, they now show a complex structure that leaves us uncertain as to their nature. That image will remain for decades the best ever image of the hemisphere not covered by the New Horizons’ flyby. 11 July, New Ho- rizons cap- tures, from a dis- tance of 4 million km, the best ever image of the op- posite hemisphere to that of the fly- by. [NASA/Johns Hopkins Univer- sity Applied Phys- ics Laboratory/ Southwest Re- search Institute] 13 July, Pluto and Charon photographed in colour, later enhanced to highlight terrains of varying composition. The distance between the two objects has been reduced. [NASA/Johns Hopkins University Applied Physics Laboratory/ Southwest Research Institute]