南极光与国际太空站
Aurora Australis and the International Space Station
Image Credit: NASA, ISS Expedition 71
Explanation: This snapshot from the International Space Station was taken on August 11 while orbiting about 430 kilometers above the Indian Ocean, Southern Hemisphere, planet Earth. The spectacular view looks south and east, down toward the planet’s horizon and through red and green curtains of aurora australis. The auroral glow is caused by emission from excited oxygen atoms in the extremely rarefied upper atmosphere still present at the level of the orbiting outpost. Green emission from atomic oxygen dominates this scene at altitudes of 100 to 250 kilometers, while red emission from atomic oxygen can extend as high as 500 kilometers altitude. Beyond the glow of these southern lights, this view from low Earth orbit reveals the starry sky from a southern hemisphere perspective. Stars in Orion’s belt and the Orion Nebula are near the Earth’s limb just left of center. Sirius, alpha star of Canis Major and brightest star in planet Earth’s night is above center along the right edge of the southern orbital skyscape.
Looking Up: International Observe the Moon Night
Tomorrow’s picture: If the Moon could smile
南极光与国际太空站
影像提供与版权: NASA, ISS Expedition 71
说明: 这张快照是国际空间站于8月11日在 地球南半球印度洋上空约430公里处拍摄的。向南方和东方的地平线看去，影像中红色和绿色的南极光，呈现出壮观的景象。这些极光是由仍然存在于与国际太空站相同轨道高度的极其稀薄的高层大气，其中的氧原子受到激发而发射的。绿色光芒来自于100至250公里高空的氧原子辐射，而氧原子所辐射的红色光芒则可延伸至高达500公里的高空。除了这些南极光的光芒之外，这张从近地轨道拍摄的景色，也从南半球的视角观测星空。猎户座腰带和猎户座星云中的恒星位于中心左侧的地球边缘附近。地球夜间最亮的恒星，天狼星，也就是大犬座的α星，位于南轨道天景右边缘的中心上方。
仰望: 国际观月夜
明日的图片: If the Moon could smile
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