A ring or circle of light around the sun or moon is called a halo by scientists. We get many messages throughout each year from people who've just spotted a ring around the sun or moon. The night before Hurricane Sandy made landfall on the U.S. mainland on October 29, 2012, for example, many on the U.S. East Coast saw a lunar halo. The night of the landfall itself, as clouds from Sandy covered the U.S. East, many in the U.S. Midwest and West saw a halo. We do not know if Sandy was responsible for these halos, but in fact lunar and solar halos are associated with nearby storms. Solar and lunar haloes are pretty common, but they're so mysterious-looking that people often express amazement upon seeing them. They want to know: what causes a halo around the sun or moon? EarthSky Facebook friend Randy Miller in Anderson, Indiana saw this lunar halo on the night Sandy made landfall on the U.S. mainland, October 29, 2012. On the night Sandy made landfall, lunar halos were seen as far west in the U.S. as the state of Washington. EarthSky Facebook friend Susan Jensen in Odessa, Washington saw and photographed this delicate halo, as Sandy was carving its path of destruction along the U.S. East Coast. There's an old weather saying: ring around the moon means rain soon. There's truth to this saying, because high cirrus clouds often come before a storm. Notice in these photos that the sky looks fairly