Halos around the sun or moon are a sign of high thin cirrus clouds drifting 20,000 feet or more above our heads. They’re pretty common. We see many, many photos of halos, especially in the winter months but also at other times of year. The two in this post are particularly nice, though. They are two solar halos spotted over separate parts of Canada, at different times of day, yesterday.
What makes a halo? Those high thin cirrus clouds clouds contain millions of tiny ice crystals. The halos you see are caused by both refraction, or splitting of light, and also by reflection, or glints of light from these ice crystals.
The crystals have to be oriented and positioned just so with respect to your eye, in order for the halo to appear. In that way, you might say that each person sees his or her own personal halo.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Prior to that, she had worked for the University of Texas McDonald Observatory since 1976, and created and produced their Star Date radio series. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. In 2020, she won the Education Prize from the American Astronomical Society, the largest organization of professional astronomers in North America. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.
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