銀河系形狀的火箭排氣螺旋
A Galaxy-Shaped Rocket Exhaust Spiral
來源：Seung Hye Yang｜發表日期：2024-03-12
地平線那邊是什麼？看起來像是附近的一個奇怪的星系，實際上是一個普通的火箭排出的煙羽--不過是不尋常的背光。 雖然 SpaceX 獵鷹 9 號火箭是從美國佛羅里達州卡納維拉爾角發射升空的，但其燃燒的推進劑在更廣闊的區域都能看到，這張照片就是從冰島阿庫雷裡拍攝的。一週前，這艘巨大的宇宙飛船升空，所產生的壯觀景象很快就被智慧手機拍攝下來，曝光時間僅為 10 秒鐘，隨後迅速消散。與夜光雲一樣，羽流的亮度也是由黃昏效應造成的，即物體高度足夠高，即使地面上的觀察者身處黑夜，也能被黃昏的太陽照亮。螺旋形狀很可能是由於強風將排出的氣體推成了開瓶器的形狀，沿著軌跡看，就像一個螺旋。在這幅非凡影像的背景中，出現了星星以及微弱的綠色和紅色極光。
原文：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.
※ 本文由萌芽機器人自動轉貼自每日一天文圖（Astronomy Picture of the Day，APOD），原文為英文，正體中文是透過 DeepL 翻譯及 OpenCC 進行自動處理，內容僅供參考，若有任何錯誤之處還請見諒！
關於每日一天文圖：每日一天文圖網站是美國國家航空暨太空總署與密西根理工大學提供的服務，網站每天提供一張影像或圖片，並由天文學家撰寫扼要說明其特別之處。