Three suns spotted in China: Rare optical phenomenon appeared over Inner Mongolia [VIDEO]

A rare celestial phenomenon has stunned people in China. They witnessed the rare phenomenon, which gives the illusion of three suns appearing in the sky.

A video of the celestial phenomenon, which was taken in Hulunbuir, Inner Mongolia, on November 28, shows the sun in the centre, while two small coloured patches or phantom suns on the left and the right side.

This phenomenon is called "sundog." According to scientists, the phenomenon occurs when the temperature goes down below minus 30 degree Celsius and when the sun interacts with vapour and ice crystals.

A resident who filmed the rare phenomenon said, "Look, there are three suns in the background."

Residents in Hulunbuir said they have seen this incident happen twice in a day and the first occurrence recorded in the morning lasted for around two hours, according to Pear Video.

Zhao Kexin, who works at the Hulunbuir Meteorological Station, said: "sun dog" often occurs in the region during winter, according to Daily Mail.

What is Sundog?

Sundogs, also known as mock suns, are visible when sunlight shines through ice crystals in the air. According to Live Science, sundogs are formed "from hexagonal ice crystals in high and cold cirrus clouds or, during very cold weather. These ice crystals act like prisms, bending the light rays passing through them."

"As the crystals sink through the air they become vertically aligned, refracting the sunlight horizontally so that sundogs are observed," Live Science explained.

This phenomenon mostly occurs when the "sun is lower on the horizon in January, April, August and October." It can happen anywhere and at any time of the year.

There have been mentions of sundogs by several Greek and Roman authors. "Two mock suns rose with the sun and followed it all through the day until sunset," Greek philosopher Aristotle (384 B.C. – 322 B.C.) noted.