直指月亮的火箭烟尘影子

2024年2月11日

Rocket Plume Shadow Points to the Moon
Image Credit: Pat McCracken, NASA

Explanation: Why would the shadow of a rocket’s launch plume point toward the Moon? In early 2001 during a launch of the space shuttle Atlantis, the Sun, Earth, Moon, and rocket were all properly aligned for this photogenic coincidence. First, for the space shuttle‘s plume to cast a long shadow, the time of day must be either near sunrise or sunset. Only then will the shadow be its longest and extend all the way to the horizon. Finally, during a Full Moon, the Sun and Moon are on opposite sides of the sky. Just after sunset, for example, the Sun is slightly below the horizon, and, in the other direction, the Moon is slightly above the horizon. Therefore, as Atlantis blasted off, just after sunset, its shadow projected away from the Sun toward the opposite horizon, where the Full Moon happened to be.

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直指月亮的火箭烟尘影子
影像提供: Pat McCracken, NASA

说明: 为何火箭发射烟尘的影子会直指月亮呢？在2001年初，亚特兰蒂斯号航天飞机发射时，太阳、地球、月亮和推进火箭都恰好排成一直线，造就了这个值得拍照留存的景观。首先，要让航天飞机的烟尘投射出长长的阴影，时间要是在日出或日落附近。只有在这种时分，影子最长且向地平线伸展。最后，如果又恰逢满月之时，太阳和月亮分落在天空的两侧；当落日刚没入地平面时，在另一端的天空，月亮会恰好浮出地平面。也因此，随着亚特兰提斯号在满月那天的日落后发射升空，推射火箭烟尘的影子，就直指东方刚升起的满月。