Free Astronomy Magazine January-February 2016

6 JANUARY-FEBRUARY 2016 PLANETOLOGY comment the most relevant news and most significant images released during the last months of 2015 by the various teams of researchers of the mission. One of the main discoveries regarding Pluto was the deposits of exposed water ice, identified by the Ralph/Multispectral Visible Imaging Camera (MVIC) and high- lighted in blue in the image above. Almost the planet’s entire surface is covered by ice elements more volatile than water, and so far the researchers do not know why it has surfaced or remained exposed in these specific regions. It may not be acci- dental that these regions coincide with areas of land particularly reddened by the contemporary presence of complex mo- lecular chains called tholins, at the origin of which there are nitrogen and methane atoms ionized in the atmosphere by the Sun’s ultraviolet radiation. The more sig- nificant traces of water ice coincide with a section along the Virgil Fossa, stretching west of Elliot crater (inset left-side), and with Viking Terra (image top left). An- other concentration of water ice involves Baré Montes, on the border with Pluto’s “heart”. The framed area is about 450 km across. The outcrops of water ice are not other than the latest demonstration of the geo- logical variety of Pluto’s surface, well re- presented in the image below (a region adjoining the top part of the previous image), in which it is clearly evident the stark contrast between the corrugated A bove, the re- gions in which exposed water ice was detected (col- oured in blue). Be- low, a high-resolu- tion image of a vast area between Viking Terra and Tombaugh Regio. On the fol- lowing page, the two cryovolcanoes high-lighted by 3-D processing. [NASA/ Johns Hopkins Uni- versity Applied Physics Laborato- ry/Southwest Re- search Institute]