NASAさんのインスタグラム写真 - (NASAInstagram)「Specular Spectacular: During its mission, our Cassini spacecraft captured the sun glinting off of Titan's north polar seas, seen in this near-infrared, color mosaic from August 21, 2014. The sunglint, also called a specular reflection, is the bright area near the 11 o'clock position at upper left. This mirror-like reflection, known as the specular point, is in the south of Titan's largest sea, Kraken Mare, just north of an island archipelago separating two separate parts of the sea. The southern portion of Kraken Mare displays a "bathtub ring" -- a bright margin of evaporate deposits -- which indicates that the sea was larger at some point in the past and has become smaller due to evaporation. The deposits are material left behind after the methane & ethane liquid evaporates, somewhat akin to the saline crust on a salt flat. Image credit: NASA/JPL-Caltech/University of Arizona/University of Idaho #Saturn #Titan #Sunglint #SolarSystem #NASA」4月22日 0時37分