This article answers the question from someone asking whether it is possible to "touch" a rainbow.
Back to touching raindrops that make a rainbow: Suppose you turn on a sprinkler and see a rainbow in the sunlit spray. You can "certainly touch the spray" that generates the rainbow, Lee and Fraser write. By the way, just as you and your friend saw different views of your nose, "each of your eyes sees a slightly different rainbow," Lee e-mails.
However, unlike the nose-image location, we can't touch the location of the rainbow image. It is behind the rainbow (at the so-called antisolar point), much as the nose image is behind the mirror. But the antisolar point is too far away to touch. Being an image of the sun, the rainbow image location is at the same distance behind the raindrops as the sun is in front — "effectively at infinity," Fraser says. It seems strange a rainbow is as far away as the sun. But, try moving. The rainbow moves with you, just as the sun does.
Now, after reading that and the article, read some of the comments left behind. You'd think they didn't read the article at all!