Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2006 April 11
探索宇宙! 每天发布一张有专业天文学家的简短解释和说明的反映我们迷人宇宙的不同影像或照片。
http://www.bjp.org.cn/files/2006 ... irds_wilson_big.jpg2006 年 04 月 11 日
A Sun Halo over Utah
Credit & Copyright: Doug Wilson
Explanation: Have you ever seen a halo around the Sun? This fairly common sight occurs when high thin clouds containing millions of tiny ice crystals cover much of the sky. Each ice crystal acts like a miniature lens. Because most of the crystals have a similar elongated hexagonal shape, light entering one crystal face and exiting through the opposing face refracts 22 degrees, which corresponds to the radius of the Sun Halo. A similar Moon Halo may be visible during the night. The picture was taken in Gunlock, Utah, USA. A flock of birds was caught by chance in the foreground. Exactly how ice-crystals form in clouds remains under investigation.
犹他州上空的日晕
版权及影像提供：Doug Wilson
你见过围绕在太阳的光晕吗？这一相当常见的景象发生在包含了成千上万的微小冰晶的高空稀薄云层覆盖天空时。每个冰晶的作用就像一个微型棱镜。由于多数冰晶是相似的六边形柱体，光进入冰晶的一个面和通过相反的一面离开便折射了22度，这与日晕的半径相符合。与之相似的月晕可以在夜间看到。图片拍摄于美国犹他州的Gunlock。一群在前景飞过的鸟偶然的被捕捉在这照片里。云中的冰晶如何形成现在还在研究中。
演讲: APOD 编辑今晚(4月11 日)在普林斯顿给公众的谈话
Lecture: APOD editor to give public talk in Princeton tonight (April 11)
Tomorrow's picture: binary black hole