People in Bengaluru witnessed a rare phenomenon on Monday morning as a rainbow circled the sun creating a halo around the star.
The halo seen across Bengaluru, owing to clear skies, was visible for over an hour as the striking colours appeared covering the Sun. The rare occurrence takes place due to the dispersion of light.
Social media went abuzz with the pictures of the Sun’s halo as people took to Twitter to share pictures of the event over Bengaluru skies.
What is Sun’s halo?
The halo that appeared around the Sun is a 22-degree ring that appears due to the dispersion of light as white light passes through ice crystals found in upper-level cirrus clouds, causing the halo to have colours. According to the University of Illinois, “The halo is a ring of light 22-degrees from the Sun or Moon and is the most common type of halo observed and formed by hexagonal ice crystals.”
The clouds contain millions of tiny ice crystals, which refract, split and even reflect the light to give an impression of a circular rainbow ring. The crystals have to be oriented and positioned just so with respect to your eye, in order for the halo to appear.
Light undergoes two refractions as it passes through the ice crystals and the bending that occurs depends on the ice crystal’s diameter. In a 22-degree halo, the kind seen in Bengaluru, light enters from one side of the ice crystal and exits through another, being refracted on both entry and exit. The two refractions bend the light by 22-degrees from its original point, producing a ring of light around the Sun or the Moon.
Seen around the Moon, lunar halos are mostly colourless as moonlight is not very bright. However, in the case of the Sun, these colours are more noticeable and appear as bright as a rainbow.
The phenomenon seen in Bengaluru was witnessed last year as well, while another such ring was seen in Tamil Nadu’s Rameswaram.
