Copyright:
Dave Lane;
Rollover Annotation: Judy Schmidt
原文:
Why would the sky look like a giant fan? Airglow. The featured intermittent green glow appeared to rise from a lake through the arch of our Milky Way Galaxy, as captured last summer next to Bryce Canyon in Utah, USA. The unusual pattern was created by atmospheric gravity waves, ripples of alternating air pressure that can grow with height as the air thins, in this case about 90 kilometers up. Unlike auroras powered by collisions with energetic charged particles and seen at high latitudes, airglow is due to chemiluminescence, the production of light in a chemical reaction. More typically seen near the horizon, airglow keeps the night sky from ever being completely dark. Follow APOD on: Facebook, Google Plus, or Twitter
中文翻譯:
為什麼天空看起來像一個巨型的風扇？這是因為空氣發光（Airglow）。這幅插圖中的綠色閃光看似從湖泊中升起，穿過我們的銀河系弧形，拍攝於去年夏天的美國猶他州布萊斯峽谷附近。這個不尋常的圖案是由大氣重力波造成的，這是一系列交替的氣壓波動，隨著高度增加而增長，此次情況約在90公里高空。與由高能帶電粒子撞擊而產生的極光不同，空氣發光是由化學發光（chemiluminescence）引起的，這是在化學反應中產生光的現象。通常在地平線附近較為可見，空氣發光使得夜空從未完全黑暗。
#空氣發光 #空氣重力波 #銀河系 #猶他州 #布萊斯峽谷 #夜空 #科學奇觀 #宇宙探索 #天文學
來源:NASA每日圖片
