A giant sun halo was spotted shining bright above the mountains in Lao Cai, Vietnam.

Footage from May 10 shows the optical phenomenon surrounding the sun. According to locals, residents flocked to the streets to get a glimpse of the rare sight.

A sun halo is caused by the refraction of ice crystals that form in Earth's lower atmosphere.

Video captured the moment of A giant sun halo that appeared in Lao Cai, Vietnam.

According to locals, the halo of the sun suddenly appeared at midday, causing everyone to flock to the street to see the rare and strange phenomenon. The sun's halo is very large and covers the entire area. Everyone can see the sun's halo.

Scientists say this halo is caused by sunlight shining through the clouds overhead. These clouds have a structure of ice crystals.

When sunlight hits it, it is refracted, creating colorful circles. The halo of the sun also has 7 colors like the rainbow (red, orange, yellow, green, blue, indigo, and purple) but the order of colors is arranged in reverse.

According to scientists, the halo around the moon is usually frequency occurs more often, while the halo is very rare and is considered an interesting weather phenomenon.