噴發的埃特納上空的光柱
Light Pillar over Erupting Etna
來源：Davide Caliò｜發表日期：2025-02-24
熔岩流可以延伸到天空嗎？不能，但熔岩流發出的光可以。火山光柱就是一種非常不尋常的效果。更典型的情況是，光柱是由太陽光造成的，因此表現為在太陽昇起或落下時向上延伸的明亮光柱。另外，在路燈和房屋燈的上方也出現過其他光柱--有些光柱色彩斑斕。不過，這個光柱是由噴發的火山岩漿發出的紅光照亮的。這座火山就是義大利的埃特納火山，這張照片是在二月中旬的一個清晨拍攝的。火山熔岩流上方的低溫在火山上方的空氣中或埃特納火山噴出的冷凝水蒸氣中形成了冰晶。這些冰晶（大部分朝向地面，但會飄動）反射走火山口的光線。
原文：Can a lava flow extend into the sky? No, but light from the lava flow can. One effect is something quite unusual -- a volcanic light pillar. More typically, light pillars are caused by sunlight and so appear as a bright column that extends upward above a rising or setting Sun. Alternatively, other light pillars -- some quite colorful -- have been recorded above street and house lights. This light pillar, though, was illuminated by the red light emitted by the glowing magma of an erupting volcano. The volcano is Italy's Mount Etna, and the featured image was captured with a single shot during an early morning in mid-February. Freezing temperatures above the volcano's lava flow created ice-crystals either in the air above the volcano or in condensed water vapor expelled by Mount Etna. These ice crystals -- mostly flat toward the ground but fluttering -- then reflected away light from the volcano's caldera.
※ 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。