Free Astronomy Magazine May-June 2016

11 MAY-JUNE 2016 PLANETOLOGY is surrounded by a thick atmosphere, composed mostly of hydrogen and helium, virtually free of water vapour and thus of oxygen, but at the same time also rich in car- bon. The massive presence on the planet of this element was already known, but the established absence of oxy- gen (at least in detectable amounts) now strengthens the hypothesis that the solid mass of 55 Cancri e is com- posed in substantial part of materials so rich in carbon that about one-third of the planet’s inner mass, where the temperatures and pressures are extremely high, maybe constituted of diamond. In short, an unpredict- able planet, far from the models imagined for the typical Earth-like planets, in which oxygen is instead a funda- mental component of the solid, liquid and gas mass. A ccording to a recent study by a team from the Univer- sity of Cambridge (UK), 55 Cancri e presents always the same hemisphere to its star. It follows that while in the lit hemisphere the temperatures can go up to 2,500 degrees C, in the dark one should not exceed 1,100 degrees C. It is very likely that due to the high temperature difference be- tween the two hemispheres, the atmosphere is swept by blustering blazing-hot winds. As shown in this video, it is possible that those extreme conditions are leading to the slow dispersion of the atmosphere. [NASA/JPL-Caltech] n