十二月的仲夏夜

2023年12月23日

A December Summer Night
Image Credit & Copyright: Ian Griffin (Otago Museum)

Explanation: Colours of a serene evening sky are captured in this 8 minute exposure, made near this December’s solstice from New Zealand, southern hemisphere, planet Earth. Looking south, star trails form the short concentric arcs around the rotating planet’s south celestial pole positioned just off the top of the frame. At top and left of center are trails of the Southern Cross stars and a dark smudge from the Milky Way’s Coalsack Nebula. Alpha and Beta Centauri make the brighter yellow and blue tinted trails, reflected below in the waters of Hoopers Inlet in the Pacific coast of the South Island’s Otago Peninsula. On that short December summer night, aurora australis also gave luminous, green and reddish hues to the sky above the hills. Aurora shine as atoms and molecules in the upper atmosphere are excited by collisions with energetic particles. An upper atmospheric glow distinct from the aurora, a pale greenish airglow caused by a cascade of chemical reactions excited by sunlight, can be traced in diagonal bands at top left.

Tomorrow’s picture: a cosmic cocoon

十二月的仲夏夜
影像提供与版权: Ian Griffin (Otago Museum)

说明: 这幅在今年冬至附近，摄于地球南半球的纽西兰之8分钟长曝光影像，记录了静谧夜空的缤纷色彩。在这片南眺的视野里，恒星旋绕着顶缘外头的南天极，曳出短短的同心圆弧状星轨。在影像的中左方，有南十字群星的星轨及煤袋星云所造成的黝黑斑块。其中，南门二及马腹一的明亮泛黄与泛蓝星轨，更倒映在南岛奥塔哥半岛太平洋沿岸胡珀斯湾的海面上。此外，在12月的这个仲夏夜里，南极光也为山丘上方的天空抺上明亮的绿与红晕。左上角斜贯的淡绿光带，则是大气受到阳光激发的一连串化学反应所发出的气辉，这种高层大气的辉光，显然有别于因高能粒子撞击而触发的极光。

明日的图片: a cosmic cocoon