2019 October 17

Moons of Saturn Image Credit: Cassini Imaging Team, SSI, JPL, NASA

Explanation: On July 29, 2011 the Cassini spacecraft’s narrow-angle camera took this snapshot and captured 5 of Saturn’s moons, from just above the ringplane. Left to right are small moons Janus and Pandora respectively 179 and 81 kilometers across, shiny 504 kilometer diameter Enceladus, and Mimas, 396 kilometers across, seen just next to Rhea. Cut off by the right edge of the frame, Rhea is Saturn’s second largest moon at 1,528 kilometers across. So how many moons does Saturn have? Twenty new found outer satellites bring its total to 82 known moons, and since Jupiter’s moon total stands at 79, Saturn is the Solar System’s new moon king. The newly announced Saturnian satellites are all very small, 5 kilometers or so in diameter, and most are in retrograde orbits inclined to Saturn’s ringplane. You can help name Saturn’s new moons, but you should understand the rules. Hint: A knowledge of Norse, Inuit, and Gallic mythology will help.

土星的卫星 影像来源: Cassini Imaging Team, SSI, JPL, NASA

说明：2011年7月29日，卡西尼号宇宙飞船的窄角照相机拍摄了这张快照，它从土星环上方捕捉到了五颗土星的卫星。它们从左到右分别是直径为179公里和81公里的小卫星土卫十和土卫十七，直径为504公里和396公里的明亮土卫二和土卫一，以及旁边的土卫五。土卫五是土星第二大卫星，直径为1528公里，被影像的右侧边缘所切断。那么土星有多少颗卫星呢？新发现的20颗外围卫星使其已知卫星的总数达到82颗，因为木星的卫星总数为79颗，所以土星是太阳系新加冕的卫星之王。这些新发布的土星卫星都非常小，直径约为5公里，而且大多数都位于与土星环面交错的逆行轨道上。你可以为这些土星的新卫星命名，但是你应该先了解命名的规则。提示一下：了解北欧、因纽特和高卢神话将会有帮助。