A ring of illuminated ice crystals encircle an Alaskan moon

Illustration for article titled A ring of illuminated ice crystals encircle an Alaskan moon

Our sun isn't the only object in the sky that can produce spectacular optical effects. Take this photograph taken by Sebastian Saarloos on a cold, starlit Alaskan night. This is what's called a "moondog" — a rainbow-like ring around the moon that's caused by the reflection of moonlight (which is reflected sunlight) from ice crystals in the upper atmosphere.

Advertisement

The slightly overexposed photograph shows misty mountains in the background, along with an icy halo that surrounds the moon. Interestingly, because all ice crystals tend to have the same hexagonal shape, the moon ring is always the same size; moondogs, also known as paraselanae, are typically seen at an angle of 22 degrees.

Photograph courtesy Sebastian Saarloos. It was taken on January 17, 2013 from Lower Miller Creek, Alaska, USA.

Advertisement
Illustration for article titled A ring of illuminated ice crystals encircle an Alaskan moon

Via NASA.

Share This Story

Get our newsletter

DISCUSSION

Spaceart
Ron Miller

The effect is caused by refraction, not reflection. Oh, and by the way...while high altitude ice crystals are usually the cause, in the case of this photo it's due to more low-lying ice crystals, which is why the halo is visible in front of the mountains.