While riding at the head of a camel caravan over the dunes of Erg Chebbi, southern Morocco, Koren Bosworth (Member 60,716) spotted a double rainbow reaching right across the sky. Rainbows form when the sunlight is separated into its constituent colours as it’s reflected and refracted by raindrops. You need your back to the Sun to see one. And when you do, try to look for the head of your shadow. Though Koren’s wide-angle lens has splayed out the curve of her desert rainbow, you’ll find in reality – just like she did – that the head of your shadow is always positioned exactly at the centre of your rainbow’s arc.