Twilight Arch Delicacy

The past couple months have been super busy with the move to Philadelphia, but I finally have some time to post-process some of this summer's photos before dental school starts. In June we hiked up to the Delicate Arch (the one on Utah license plates) and stayed up there for a few hours till the stars came out. There was so little light pollution that I was able to get this great shot! Can you guess what the amber light is down in the valley?