A moon halo (née 22° halo) is caused when moonlight refracts through ice crystals suspended in the upper atmosphere. While not entirely uncommon, the optical phenomenon was quite a sight as it framed one of the Bay Area’s most iconic spans.
The aforementioned halo and supermoon kick off a series of celestial events, including a total lunar eclipse and super-blue moon.
According to San Jose Mercury News, “January’s super-blue moon will occur during a total lunar eclipse, when the Earth’s shadow will completely block the sun’s light from the moon.”
Look for the total lunar eclipse on the evening of January 31.