Well, I thought it was funny

How far away is a rainbow?

I can see a rainbow from my kitchen door. The bottom ends of the rainbow are clearly in front of the hills on the other side of the valley, which are about four miles away, so it appears to be about two miles away.

But a rainbow is a virtual image and it's always the same distance from you (the same as the horizon at sea is always about twenty miles away) so how far away is the virtual image? Does anybody know?

PS - the red is on the outside/top of the rainbow - in one of the books that my kids brought home from school, they had put red at the bottom. Sheesh! When remembering the colours, I like the following mnemonic best 'Richard of York got captured by Martians' (red, orange, yellow, green, cyan, blue, magenta)

PPS - except in the rare case of a double-rainbow, when there's a faint upside down rainbow above the main one.