Blue moon last night!

[Superfluous J]

90% is nonsensical and pulled out of nowhere, true, but it's easy to figure out what the guy meant. The Moon takes 100% of an orbit to go around Earth. 90% of that time, it's outside of the "potential supermoon zone" and 10% of the time it's inside that zone. If the Moon is inside that zone when it's full, then it's a Supermoon.

Now you can argue if those zones should be based on circular arc, actual length of the elliptical arc, or time it takes the Moon to pass through (all 3 different) but it's pretty obvious the guy didn't mean "Whenever the Moon is closer to the Earth than the Moon ever gets to the Earth."

Give the guy a break. He's an astrologer. I'm impressed he even knows the Moon has a perigee.

[Tw1]

My photo from that night.

Not even edited.

Though I may have tweaked the camera's white balance.

Edited August 4, 2015 by Tw1