Question

When and where does a rainbow appear in the sky? List the phenomena of light in proper sequence which occurs during the formation of a rainbow. Why can a rainbow not be seen from the surface of the moon?

Answer 1

A rainbow appears in the sky after rainfall when the sun is shining. It is seen in the part of the sky opposite the sun.

The phenomena of light involved in rainbow formation, in proper sequence, are:

1. Refraction: Sunlight enters raindrops and is refracted (bent) because light travels slower in water than in air. Different wavelengths of light are refracted at slightly different angles.
2. Reflection: The refracted light then reflects off the inner surface of the raindrop.
3. Dispersion: As light is refracted and reflected, it is dispersed into its constituent colors (spectrum) because different wavelengths (colors) of light bend at slightly different angles.
4. Second refraction: The dispersed light then exits the raindrop, undergoing a second refraction as it passes from water to air.

A rainbow cannot be seen from the surface of the moon because:

A rainbow requires sunlight to be refracted and reflected by water droplets in the Earth's atmosphere. On the moon, there is no atmosphere, and hence no water droplets to cause refraction and reflection of sunlight. Therefore, a rainbow cannot be formed on the moon's surface.