马尼托巴上空的月华、月晕和切弧

2020 February 24

Moon Corona, Halo, and Arcs over Manitoba
Image Credit & Copyright: Brent Mckean

Explanation: Yes, but could you get to work on time if the Moon looked like this? As the photographer was preparing to drive to work, refraction, reflection, and even diffraction of moonlight from millions of falling ice crystals turned the familiar icon of our Moon into a menagerie of other-worldly halos and arcs. The featured scene was captured with three combined exposures two weeks ago on a cold winter morning in Manitoba, Canada. The colorful rings are a corona caused by quantum diffraction by small drops of water or ice near the direction of the Moon. Outside of that, a 22-degree halo was created by moonlight refracting through six-sided cylindrical ice crystals. To the sides are moon dogs, caused by light refracting through thin, flat, six-sided ice platelets as they flittered toward the ground. Visible at the top and bottom of the 22-degree halo are upper and lower tangent arcs, created by moonlight refracting through nearly horizontal hexagonal ice cylinders. A few minutes later, from a field just off the road to work, the halo and arcs had disappeared, the sky had returned to normal — with the exception of a single faint moon dog.

Tomorrow’s picture: Jupiter-sized magnet

马尼托巴上空的月华、月晕和切弧
影像来源及版权：Brent Mckean

说明：要是月亮变成了这个样子你还会去工作吗？正当这位摄影师准备开车去上班时，被数以百万计的正在下落的冰晶所折射，反射，甚至衍射的月光将我们所熟知的月亮形象变成了由光晕和光弧构成的奇妙景色。这幅图像由三张照片合成而来，是在两周前一个寒冷的冬日清晨在加拿大马尼托巴省拍摄的。彩色的圆环是月华，是由月亮视线方向的小水滴或小冰粒的量子衍射造成的。在它外围是六面柱形冰晶折射月光形成的22°半径的月晕。侧面是月狗，是降向地面的又薄又平的六面冰片折射光线的结果。在22度月晕的顶部和底部可见上、下晕切弧，这是月光被几乎水平的六角形冰柱体折射而成。在上班路旁的这个地点，几分钟之后月晕和切弧消失不见了，除了一个暗弱的月狗，天空又恢复了正常的样子。

明日一图预告：Jupiter-sized magnet