2018年12月31日:女巫头星云-（The Witch Head Nebula）--原图下载
Image Credit & Copyright: Digitized Sky Survey (POSS II); Processing: Utkarsh Mishra
说明: 劳累叠着劳累，麻烦叠着麻烦…；烈火猛燃，大锅沸腾（沙翁名剧〈马克白〉之一幕)──或许，马克白应该转而就教于女巫头星云。这个外形颇让人惊吓的反射星云，离我们约有800光年远；它恶毒的脸孔，似乎在瞪视邻近、位在影像右端之外的猎户座亮星参宿七。这团编录号为IC 2118的星际尘埃与气体云，大小将近有70光年，其尘埃微粒不停的反射参宿七的星光。在这幅组合影像里，星云的色泽除了是受到参宿七强烈泛蓝星光的渲染之外，也因其尘埃微粒散射蓝光的效率高于红光。相同的物理过机制，也造就了地球白画的蓝天，只不过在地球大气中，散射光的粒子是氮和氧分子。
原文：
Image Credit & Copyright: Digitized Sky Survey (POSS II); Processing: Utkarsh Mishra
Explanation: Double,double toil and trouble;Fire burn, and cauldron bubble .... maybe Macbethshould have consulted the Witch Head Nebula.A frighteningly shapedreflection nebula, thiscosmic crone is about 800 light-years away though.Its malevolent visage seems to glare toward nearby bright star Rigel in Orion,just off the left edge of this frame.More formally known asIC 2118,the interstellar cloud of dust and gas is nearly 70 light-years across,its dust grains reflecting Rigel's starlight.In this composite portrait, the nebula's coloris caused not only by the star's intense bluish light but because thedust grainsscatter blue light more efficiently than red.The same physical process causesEarth's daytime sky to appear blue,although the scatterers inplanet Earth's atmosphere are molecules of nitrogen and oxygen.
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