What could they be?
I think they have something to do with interfering wave fronts. A small mound on the moon blocks the midsection of a photon from the sun. This forms something like what we see with the Schlieren effect but with even greater distance and multiple focal points.
https://youtu.be/4tgOyU34D44
Veritasium is so cool if they made a Steem account Steem value would soar.