Free Astronomy Magazine September-October 2014

14 SEPTEMBER-OCTOBER 2014 SMALL BODIES very different from the spherical one, but 67P/Churyu- mov-Gerasimenko goes beyond what we have seen so far, appearing almost like a contact-binary comet con- sisting of a round block resting on a second more elon- gated shaped block. In subsequent shots taken on 29 July from a distance of 1950 km, the two blocks appear bonded together by a “neck” probably formed by debris and dust. The entire structure measures more than 4 km on the longest axis and 3.5 km on the shortest. It is not yet en- tirely clear the mechanism by which a cometary nucleus can take that form, but it is likely to be the result of a collision at low speed between two independent nuclei –speed that in the case of 67P/Churyumov-Gerasimenko I n the background, a rendering of Rosetta entering into orbit around the comet. The artist could not have imagined the entire- ly different form of the nucleus. [ESA, image by AOES Medialab] Top left, a video showing the thousand faces of 67P/Churyumov- Gerasimenko photographed by OSIRIS during the approach phase. Left, an image of the comet taken on 8 August from just 81 km away. Very noticeable is its “neck”. [ESA/Rosetta/NAVCAM]