Upload & Sell: Off
If you ever really see the moon with strong enough optics, you'll see the result of the atmosphere 'boiling'. It looks like a coin at the bottom of a swimming pool.
One single frame will be so soft it looks like something was wrong (missed focus, lens out of alignment, etc.). By 'stacking' multiple images, you collect the sharpest portions of the individual frames into one image.
I'm working on a 127-shot stack today.