This sort of halo is called a 22 degree halo by skywatchers. You can see them around both the sun and moon. They’re caused by ice crystals in the air. They bear that name because the radius of the ring is always approximately 22 degrees. Yuri Beletsky works for the Carnegie Observatories, based at Las Campanas in northern Chile, home to the twin Magellan telescopes, and site of the future Giant Magellan Telescope. Yuri is a fantastic nature photographer; you can follow his Nightscapes on Facebook. He posted this image on Facebook on August 10, 2019, and wrote: Even when the weather is bad, we astronomers, never lose hope. Cloudy weather, it’s the worst nightmare for us. But at the same time the nature can surprise us with stunning views during those nights. Here is an amazing 22 degree halo around the moon just above the Magellan telescope 🙂 The brightest ‘star’ on the left is the planet Jupiter. Besides, you can see some stars through the clouds. I hope you’ll enjoy the view.
Source: Spectacular moon halo seen over Magellan telescope in Las Campanas, Chile