Asked by: Tom Roberts, Liverpool
A rainbow isn’t a fixed object that hangs in the sky. It’s an illusion formed between the sunshine, the rain and your eyes. Light bounces out of the raindrops at an angle of 40° for red light, and 42° for blue. And that’s true wherever you stand, so as you move, the rainbow moves too and you can never catch it.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.