Question

why no rainbow is observed from the surface of the moon

Answer 1

It does not rain on the moon.
http://en.wikipedia.org/wiki/Rainbow

Answer 2

Wait. I heard that there is liquid on the moon. If there's liquid, and the sun can shine on the moon, why is there no rainbow?

Answer 3

Don't you need an atmosphere to make a rainbow visable?

Answer 4

That's true.

Answer 5

The angular difference between the red and blue rays is 1.6 degrees. The moon is so far away that the spectrum as seen on earth is spread over a thousand miles by the time the spectrum reaches the moon.