You've probably seen the striking image on your Instagram feed: a towering wall of stone cut down the center by what appears to be a glowing stream of lava flowing down the rock face.
The sight at Yosemite National Park — not actually a lava flow but a waterfall streaming down the face of El Capitan and illuminated spectacularly by a February sunset, has captured the interest of millions and drawn flocks of park visitors.
Next year, for the second year in a row, reservations will be required to enter the park during peak time for the "firefall," as the phenomenon is known.
