參宿七和巫婆頭星雲
Rigel and the Witch Head Nebula
來源：Simone Curzi｜發表日期：2024-10-31
在星光的照耀下，這個陰森恐怖的面孔在黑暗中閃閃發光，彎曲的輪廓讓人聯想到它的俗名--巫婆頭星雲。事實上，這幅迷人的望遠鏡肖像給人的感覺就像是一位女巫將目光定格在獵戶座明亮的超巨星參宿四上。更正式的名稱是 IC 2118 ，巫婆頭星雲的跨度約為 50 光年，由反射參宿七星光的星際塵粒組成。巫婆頭星雲的顏色不僅是由裡傑爾的強烈藍光造成的，還因為塵粒散射藍光的效率比散射紅光更高。同樣的物理過程也會使地球白天的天空呈現藍色，儘管地球大氣中的散射體是氮和氧分子。參宿七和這顆佈滿灰塵的宇宙老嫗相距大約 800 光年。不過今晚你可能還是會在你家附近看到幾個女巫，所以祝你萬聖節平安快樂！
原文：By starlight, this eerie visage shines in the dark with a crooked profile evoking its popular name, the Witch Head Nebula. In fact, this entrancing telescopic portrait gives the impression that a witch has fixed her gaze on Orion's bright supergiant star Rigel. More formally known as IC 2118, the Witch Head Nebula spans about 50 light-years and is composed of interstellar dust grains reflecting Rigel's starlight. The color of the Witch Head Nebula is caused not only by Rigel's intense blue light, but because the dust grains scatter blue light more efficiently than red. The same physical process causes Earth's daytime sky to appear blue, although the scatterers in Earth's atmosphere are molecules of nitrogen and oxygen. Rigel and this dusty cosmic crone are about 800 light-years away. You may still see a few witches in your neighborhood tonight though, so have a safe and Happy Halloween!
※ 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！
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