土卫十二的彩色影像

2023年4月30日

Saturn’s Moon Helene in Color
Image Credit: NASA, JPL-Caltech, SSI; Processing: Daniel Macháček

Explanation: Although its colors may be subtle, Saturn’s moon Helene is an enigma in any light. The moon was imaged in unprecedented detail in 2012 as the robotic Cassini spacecraft orbiting Saturn swooped to within a single Earth diameter of the diminutive moon. Although conventional craters and hills appear, the above image also shows terrain that appears unusually smooth and streaked. Planetary astronomers are inspecting these detailed images of Helene to glean clues about the origin and evolution of the 30-km across floating iceberg. Helene is also unusual because it circles Saturn just ahead of the large moon Dione, making it one of only four known Saturnian moons to occupy a gravitational well known as a stable Lagrange point.

Tomorrow’s picture: stars with colors

土卫十二的彩色影像
影像提供: NASA, JPL-Caltech, SSI; 影像处理: Daniel Macháček

说明: 尽管其颜色或许很平淡，但土卫十二（Helene）不管怎么看都是个谜样的天体。在2012年，当时绕行土星的卡西尼号宇宙飞船，俯冲到离这颗娇小卫星不到1个地球直径的距离，并为它拍下了一批上面这种前所未见的细致影像。而在上面这幅影像里，除了可见到寻常的撞击坑和山丘之外，更记录了看起来异常平滑的带纹原野。行星天文学家正在检视土卫十二的这些细致影像，一点一滴的收集攸关这座30公里宽漂浮冰山的起源和演变之线索。土卫十二的其他不寻常之处，还有它绕行土星的轨道位置，正好在大卫星土卫四（Dione）的前方，这使它成为现知的4颗、位于名为稳定拉格朗日点（重力井）里的土星卫星之一。