A climber in Wales has spotted an extraordinary sight.
Sam Clack had spent four hours scaling Mount Snowdon when he spied what's known as a circular rainbow.
The effect was caused by the sun, which was behind Sam, projecting his shadow on to mist in the air, creating what looked like a multi-coloured halo. Its proper name is the magical-sounding Brocken Spectre, named after a peak in the Harz mountains of Germany, where it was first identified.
"I met a retired physics teacher [when I got to] the top," Sam revealed, "who managed to explain it - when he'd lifted his jaw from the floor. I have never seen one before and may never see another. It was definitely a privilege to have witnessed it."