Scientists at NASA’s Jet Propulsion Laboratory in Pasadena, California, have discovered why comets are encased in a hard, outer crust. This false-color four-image mosaic comprises images taken from a distance of 28.7 km from the center of Comet 67P/Churyumov-Gerasimenko on 3 February 2015. The mosaic measures 4.2 x 4.6 km. Image credit: ESA / Rosetta / NAVCAM / CC BY-SA IGO 3.0. Using a unique cryostat instrument called Himalaya, they show that...
