银河周围的彩色带状气辉

2022年3月13日

Colorful Airglow Bands Surround Milky Way
Image Credit & Copyright: Xiaohan Wang

Explanation: Why would the sky glow like a giant repeating rainbow? Airglow. Now air glows all of the time, but it is usually hard to see. A disturbance however — like an approaching storm — may cause noticeable rippling in the Earth’s atmosphere. These gravity waves are oscillations in air analogous to those created when a rock is thrown in calm water. Red airglow likely originates from OH molecules about 87-kilometers high, excited by ultraviolet light from the Sun, while orange and green airglow is likely caused by sodium and oxygen atoms slightly higher up. While driving near Keluke Lake in Qinghai Provence in China a few years ago, the photographer originally noticed mainly the impressive central band of the Milky Way Galaxy. Stopping to photograph it, surprisingly, the resulting sensitive camera image showed airglow bands to be quite prominent and span the entire sky. The featured image has been digitally enhanced to make the colors more vibrant.

Tomorrow’s picture: star hatchery

银河周围的彩色带状气辉
影像提供与版权: Xiaohan Wang（王笑寒）

说明: 为何天空发出像庞大彩虹的连绵辉光？因为有气辉。其实地球的大气随时都在散发辉光，只是一般的情况下难以察见。不过，当有风暴系统这类的扰动接近时，可能就会在地球的大气里激发出可见的涟漪。这种称为重力波的大气振荡，类似往平静水塘掷石所激起的水波。其中，泛红的气辉，可能是87公里高处附近受到太阳紫外光激发的OH分子，而橙色和绿色气辉，可能是源自稍高之处的钠原子和氧原子。当时开车经过中国青海省的克鲁克湖附近的这位摄影者，原先注意到的是壮观的银河系盘面，并停车拍摄。但所拍下的高灵敏相机影像，却很意外的也记录了绵延整个天空的清晰带状气辉。

明日的图片: star hatchery