The sun shines through Martin's Hole, a natural gap just underneath the jagged ridge of Mount Grosses Tschingelhorn (2849 metres/9347 feet) near the eastern Swiss alpine village of Elm on Wednesday. Twice a year, about eight days before the start of spring and again about eight days after the beginning of autumn, the rising sun sends its rays through the 19-meter wide hole in the mountain face before clearing the ridge.