Did you see the 'halo' around the moon? What it is and when it might happen again

If you looked up at the night sky during the past 24 hours, you might have seen a ring around the moon. Viewers from all over the nation and even in other parts of the world were able to see the halo, leaving skywatchers wondering what it was.

According to Space.com, “The moon's halo or lunar halo is an optical illusion that causes a large bright ring to surround the moon. This striking and often beautiful halo around the moon is caused by the refraction of moonlight from ice crystals in the upper atmosphere.”

Scientists refer to this phenomenon as a 22-degree halo. According to Earth Sky, “They got that name because the radius of the circle is always approximately 22 degrees.”

Why is there a ring around the moon?

These halos are caused by high cirrus clouds positioned approximately 20,000 feet above the ground that contain tiny ice crystals. The halos result from the refraction and reflection of light by the ice crystals, and their appearance is associated with old weather folklore that suggests rain soon follows, according to Earth Sky.

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Through the same process, the same thing phenomenon can happen to the sun resulting in a sun halo.

How rare is a moon ring?

Moon rings or halos are not extremely rare. They are a relatively common optical phenomenon, but their occurrence depends on several factors, including the presence of high-altitude cirrus clouds containing ice crystals and specific weather conditions.

Moon halos are more commonly observed in colder climates and during the winter months in areas where temperatures are consistently cold and cirrus clouds are present. However, they can still occur in other seasons and locations under the right atmospheric conditions, like the recent moon halo visible in Arizona.

More sky-gazing:The Geminid meteor shower will be extra bright this year. Here's when it peaks in Arizona

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