Auriel's Bow

Use the special power of Auriel's Bow - a Dawnguard item. You obtain the bow at the climax of the Dawnguard main quest (Forgotten Vale / Touching the Sky). Its power: shoot a Sunhallowed or Bloodcursed Elven arrow into the sun (fire a Sunhallowed arrow skyward on a clear day) to trigger the effect. Craft the special arrows with Knight-Paladin Gelebor, then fire one at the sun.