行星际空间里的地球

2024年11月23日

Interplanetary Earth
Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA & NASA / JHU Applied Physics Lab / Carnegie Inst. Washington

Explanation: In an interplanetary first, on July 19, 2013 Earth was photographed on the same day from two other worlds of the Solar System, innermost planet Mercury and ringed gas giant Saturn. Pictured on the left, Earth is the pale blue dot just below the rings of Saturn, as captured by the robotic Cassini spacecraft then orbiting the outermost gas giant. On that same day people across planet Earth snapped many of their own pictures of Saturn. On the right, the Earth-Moon system is seen against the dark background of space as captured by the sunward MESSENGER spacecraft, then in Mercury orbit. MESSENGER took its image as part of a search for small natural satellites of Mercury, moons that would be expected to be quite dim. In the MESSENGER image, the brighter Earth and Moon are both overexposed and shine brightly with reflected sunlight. Destined not to return to their home world, both Cassini and MESSENGER have since retired from their missions of Solar System exploration.

Tomorrow’s picture: interstellar journey

行星际空间里的地球
影像提供: Cassini Imaging Team, SSI, JPL, ESA, NASA & NASA / JHU Applied Physics Lab / Carnegie Inst. Washington

说明: 2013年7月19日人类达成了一项行星际创举，在一天内从太阳系不同的二颗行星（最内围的水星及最外围的庞大环系气态土星）为地球拍照。在当时由绕行土星的卡西尼号太空船拍摄的上左图里，地球是土星环系下方的淡蓝小光点。于同一天，地球各地的人们也各自拍下了许多土星影像。上右影像，则是由当时绕行水星的信使号所拍摄的，其中地球及月亮系统漂浮在黝黑的太空里。信使号拍摄的这张影像，是它寻找预期极为昏暗的水星天然小卫星工作的一部分。在信使号拍摄的影像里，左侧的地球和右侧的月亮，因为反射阳光，故极为明亮而过度曝光。不会再返回地球的卡西尼号和信使号，已先后从探索太阳系的任务除役。