The full moon appears in the night sky, surrounded by an ethereal halo caused by the moon's light passing through ice crystals in the atmosphere. Photo / Alex Robertson
The full moon appears in the night sky, surrounded by an ethereal halo caused by the moon's light passing through ice crystals in the atmosphere. Photo / Alex Robertson
Opinion
If you were admiring the full moon earlier this week you might have noticed a ring around the moon (pictured).
Known as a moon halo or 22-degree halo, the phenomenon is surprisingly common.
“A halo forms when light passes through ice crystals in the atmosphere, typically within thin high cloudslike cirrostratus,” Kgolofelo Dube, a meteorologist with MetService said.
“As the light enters and exits these crystals, it bends, with most rays being deflected at an angle of around 22 degrees, creating a bright circular ring around the moon,” Dube said.
These lunar halos are more common in winter, although they do occur all year round.
The high cirrus cloud associated with halos usually indicates impending unsettled weather, according to space.com, and the phenomenon has even inspired poetry.
“If the moon show a silver shield, Be not afraid to reap your field; But if she rises haloed round, Soon we’ll tread on deluged ground,” is one reference by George Latimer Apperson that appears in the Dictionary of Proverbs.
So if you see a halo around the moon, it might mean some bad weather soon.
