What is the rainbow with the sun as the center?

Solar halo is a light phenomenon formed by refraction when sunlight passes through ice crystals in clouds, which surrounds the sun in a ring shape and is colored. The appearance of solar halo often indicates that the weather will change to some extent.

Halo is a colorful (or white) halo or light arc around the sun formed by cirrus clouds and cirrostratus, and the color bands are arranged in infrared purple. Solar halos are sometimes called "sun flail", including total halos and intermittent halos.

According to experts, the solar halo is formed by the refraction or reflection of ice crystals when sunlight passes through cirrostratus. When light enters the ice crystals in cirrostratus, it is refracted twice and dispersed into light of various colors in different directions. In fact, when there is cirrostratus, there are countless ice crystals floating in the sky. The ice crystals in the same circle around the sun can refract the light of the same color into our eyes, forming an internal infrared purple halo. When cirrostratus composed of ice crystals appears in the sky, one or more colored rings often appear around the sun, and sometimes many colored or white spots and arcs appear, which are collectively called halo.

The following websites all have pictures.

As for your second question, I don't know.