The illumination of this shot is an optical illusion. light appears to be radiating from directly behind the arch, however that is somewhat false.
The inner arch is colored orange by the setting moon 90 degrees to the left. The cloud streaks are picking up a slight hint of dawn from the sun rising 90 degrees to the right.
The star trails are a combination of 28 three-minute exposures. The clouds only appeared for the last two exposures.
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Copyright Colin H. Sillerud
This image may not be used without my written permission.