A Halo Around the Moon

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Date : 2005. 05. 20. 23:03 (KST)
Object : A Halo Around the Moon.
Location : Gapyeong-gun, Gyeonggi-do
Camera : Canon EOS 20D digital camera.
Lens : Sigma 17-35mm(F2.8-4).
Focal Length : 17mm (DC 28mm)
F ratio : 3.5
Exposure : 13 sec.
ISO(ASA) : 200
Colorspace : sRGB
Exposure Mode : Manual exposure
Photographic Method : Fixed Tripod
Photographer : B. S. Yeom
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Have you ever seen a halo around the Moon?
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 Moon Halo. A similar Sun Halo may be visible during the day.
The picture was taken in near Seoul, South Korea. The distant planet Jupiter appears by chance just to the right of the Moon. Exactly how ice-crystals form in clouds remains under investigation.

달의 왼쪽에 있는 별은 처녀자리의 1등성인 스피카(Spica)이고, 오른쪽의 밝은 천체는 목성(jupiter)입니다. ^^ 28mm 화각으로는 잡기가 조금 어렵네요. 역시 1.6배 크롭바디 SLR 디지털 카메라에서 광각의 아쉬움은...

cf. 무지개는 보너스입니다. ^^