形似星系的火箭螺旋状烟尘

2024年3月12日

A Galaxy-Shaped Rocket Exhaust Spiral
Credit & Copyright: Seung Hye Yang

Explanation: What’s that over the horizon? What may look like a strangely nearby galaxy is actually a normal rocket’s exhaust plume — but unusually backlit. Although the SpaceX Falcon 9 rocket was launched from Cape Canaveral in Florida, USA, its burned propellant was visible over a much wider area, with the featured photograph being taken from Akureyri, Iceland. The huge spaceship was lifted off a week ago, and the resulting spectacle was captured soon afterward with a single 10-second smartphone exposure, before it quickly dissipated. Like noctilucent clouds, the plume’s brightness is caused by the Twilight Effect, where an object is high enough to be illuminated by the twilight Sun, even when the observer on the ground experiences the darkness of night. The spiral shape is likely caused by high winds pushing the expelled gas into the shape of a corkscrew, which, when seen along the trajectory, looks like a spiral. Stars and faint green and red aurora appear in the background of this extraordinary image.

Tomorrow’s picture: bird in red and blue

形似星系的火箭螺旋状烟尘
影像提供与版权: Seung Hye Yang

说明: 悬在地平线上方的物体是什么？这团看似奇特邻近星系的物体，实际上是受到摄影者背后阳光照耀的火箭羽状烟尘。尽管太空探险公司猎鹰9号火箭的发射地点，是美国佛罗里达州的卡纳维拉尔角，然而火箭的推进燃料火光之可见区域相当宽广，这张摄于冰岛阿克雷里镇的主题照片即可为见证。这艘庞大的宇宙飞船是在1星期前发射的，而这幅摄于发射后不久的影像，则是在发射烟尘消散前用智能手机进行10秒长曝光所得。就如同夜光云一样，这团烟尘之所以很明亮是因为暮曙光效应，意指对笼罩在夜幕下的地面观察者，如果所见的物体高悬、受到暮曙光时分太阳的照耀，会显得格外明亮。而其螺旋的外观，可能是烟尘受到沿视线方向的强风之吹袭，被推挤成拔塞钻的形状，故在视线方向看似螺旋。于这张精彩影像的背景里，还可见到恒星和淡淡的泛绿和泛红极光。

明日的图片: bird in red and blue