Lunar Halo Over San Bartolomé Milpas Altas, Guatemala
August 23, 2019
Photographer: Denis Hernández
Summary Authors: Denis Hernández; Jim Foster
Featured above is a composition of 6 photographs showing a 22-degree halo around the Moon as observed from San Bartolomé Milpas Altas, Guatemala, on August 12, 2019. The elevation here is 6,860 ft (2,090 m). Light pollution from a nearby community, primarily street lighting, made capturing this image a bit of a challenge. However, I climbed onto the roof of my house and was surprised to see just how bright and beautiful this halo appeared when much of the extraneous light had been blocked out.
22-degree halos are caused by minimum deviation of light through the 60-degree prisms of hexagonal ice crystals. They take shape when moonlight is redirected by ice crystals in cirrifrom clouds. If most of the crystals are randomly oriented, then the refracted light from the myriad crystals will form a circle of light.
Photo Details: Camera: SONY ILCE-3500; Software: Adobe Photoshop CC 2017 (Windows); Exposure Time: 30.000s; Aperture: ƒ/5.6; ISO equivalent: 100; Focal Length (35mm): 30.