Astronomy Picture of the Day——地球的蓝色时刻

Planet Earth at Blue Hour 
Image Credit & Copyright: Matthias Ciprian

Explanation: Nature photographers and other fans of planet Earth always look forward to the blue hour. That's the transition in twilight, just before sunrise or after sunset, when the Sun is below the horizon but land and sky are still suffused with beautiful bluish hues of light. On August 8 this early morning blue hour panorama scanned along the clear western sky, away from the impending sunrise. A breathtaking scene, it looks down the slopes of Mt. Whitney, from along the John Muir Trail toward rugged peaks of planet Earth's Sierra Nevada mountain range. Above the horizon a faint pinkish band of back scattered sunlight, the anti-twilight arch or Belt of Venus, borders the falling grey shadow of Earth itself. Subtle bands of light across the clear sky are anti-crepuscular rays, defined by shadows of clouds near the sunward horizon. Actually following parallel lines they seem to converge along the horizon at the point opposite the rising Sun due to perspective.

地球的蓝色时刻

摄影爱好者们总是期待着地球蓝色时刻的到来，那是黄昏的过渡，发生在日出之前或日落之后，这时太阳位于地平线下方，但陆地和天空仍然闪耀着美丽的蓝色光芒。这幅照片拍摄于8月8日清晨，蓝色的地球呈现了日出之前的晴朗西方天空。这是一幅震撼人心的照片，其中从惠特尼山的山坡向下俯瞰，沿着约翰·缪尔径一直延伸到内华达山脉的崎岖山顶。地平线上方散射的淡粉色光带是反辉光弧或金星带，与地球本身下落的灰色阴影相邻。而晴朗天空中的几束微弱光带是反曙暮辉，以地平线附近的云层阴影为界。实际上，由于视角的问题，这些平行光线似乎沿着地平线、在与初升太阳相对的一点汇聚。

高清原图地址：

https://apod.nasa.gov/apod/image/1910/2019-08-08-JMT19_1521-Pano-Edit.jpg

近期文章：

Astronomy Picture of the Day——空中的流星和银河

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Astronomy Picture of the Day——精灵闪电的高清影像

NASA

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