Arun
Last Activity: 7 Years ago
A rainbow is a reflection of sunlight, diffracted into its spectrum, on water droplets in the atmosphere. The spherical shape of water droplets aligns the spectrum into a band of parallel rays.
Since it is a reflection of the sun, a rainbow can only be seen at the geometric locus of points in the sky that form a specific angle between the sun, themselves and the observer. That locus is a circle and at the center of the circle should be the point in sky directly opposite to the sun, since the droplets reflect the light backwards at a 40-42 degree angle from the incident trajectory.
Fully circular rainbows have been observed from airplanes, with the airplane's shadow at their center