TL;博士:这肯定是可能的从地球同步轨道,35786公里的高度。也有可能从一个高空气象气球。——一个关键的问题是,《终结者》并不是一条直线。由于地球的大气层,终结者是一个乐队,直径约1000公里,黑暗逐渐过渡,从阳光灿烂的。最多纬度阳光尤其是开始减少在日落之前至少10分钟,但可以继续户外活动半小时或更多日落之后。(反向适用于日出。)40分钟或更长时间跨度对应于一个非常宽的频段。即使是sr - 71几乎已经看到~ 1000公里宽乐队从阳光转换为黑。除了几乎没有被足够高,sr - 71的另一个问题是,他们的发展速度。苍蝇的东西更高比sr - 71但是苍蝇多,比需要一个sr - 71慢得多。 That would be a high altitude weather balloon. A high altitude weather balloon (30 km or higher) could see both the bright and bright sides of that 1000 km band, and it could see that band slowly moving. Even higher up (much higher up), that widish band doesn't look at that wide from the perspective of a geostationary satellite. Now it does looks a bit like a line. Just as is the case with a geostationary high altitude weather balloon, a geostationary satellite would be able to see the terminator (now a line rather than a band) move over the more or less stationary Earth.