The refraction of light (in this case sunlight) through ice crystals is known as a 22-degree halo. Photo / Jim Birchall
A strange halo effect around the sun excited people on the Hauraki Plains near Thames on Tuesday morning.
A HC Post reporter snapped pictures of the phenomenon, which witnesses have described as looking like the Death Star from the movie Star Wars. Sadly for fans of the science fiction franchise,
the explanation for the halo is fully grounded in science fact.
MetService meteorologist Peter Little said the optical phenomenon is caused by the refraction of light through ice crystals, and is known as a "22-degree halo".
"The cloud type associated with these halos is commonly cirrostratus."
Little directed people to a blog on the MetService site about atmospheric optics that describes clouds high in the atmosphere that combine with ice crystals and act like prisms. The prisms separate the various wavelengths of light from one another and sometimes create a rainbow colour effect.
