Before you can obtain this achievement, you must first acquire Auriel’s Bow by completing the quest
“Touching the Sky”. The quest is given by
Serana while she is your follower and is the second to last quest in the Dawnguard storyline. She will travel with you to the Forgotten Vale and the bow will be given to you by
Gelebor after locating him in Darkfall Cave. You must then kill Gelebor’s brother, Arch-Curate Vyrthur, before he will turn over the bow.
Upon killing Arch-Curate Vyrthur, Gelebor will reward you with Auriel’s Bow along with 12 Sunhallowed Elven Arrows and 12 Normal Elven Arrows. Gelebor will then inform you that he will craft more Sunhallowed Elven Arrows if you give him Normal Elven Arrows. The Normal Elven Arrows can also be given to Serana and she will anoint them with her blood transforming them into Bloodcursed Elven Arrows.
How Auriel’s Bow Affects the Sun:Firing a Bloodcursed Elven Arrow into the sun will cause it to eclipse and cast an ugly red corona until it sets that evening. This effect will be gone the following morning.
Firing a Sunhallowed Elven Arrow into the sun will cause it to flare up and it will cast rays of light that will damage nearby enemies. This effect has a fairly short duration.
To obtain the achievement, the player must fire either a
Sunhallowed Elven Arrow or a
Bloodcursed Elven Arrow into the sun. Obviously, this requires the sun to be in the sky, so you cannot do this at night. You can, however, still fire the arrow into the sun through cloud cover.
To fire the bow, equip it (and be sure to equip the Sunhallowed or Bloodcursed Elven Arrows as well), aim at the sun and then hold down
and release. The achievement will unlock as soon as the arrow affects the sun.
If nothing happens when you fire the bow, try unequipping everything (armor and weapons). Then re-equip the bow and arrow and try again. That worked for me for some reason. **Cheers to Elder Martin for the tip**
Good luck and enjoy Skyrim on the One!