A perfect lunar halo was spotted in the sky of Pingtan county, Fujian province on March 31.

The unusually large and clear halo descended at around 8 pm, resembling a large colorful ring.

This phenomenon is caused by moonlight refracted from ice crystals in the upper atmosphere. The shape of the ice crystals focuses the light into a ring, said Deng Yiqin, a local weatherman.

Keen-sighted observers could make out the colors of the rainbow inside the ring. Usually, lunar halos are soft white and lack vivid colors.

A lunar halo appears over Pingtan, Fujian province, March 31. [Photo/ptnet.cn]