Expert: Philip Stahl - 5/22/2008

Question
Hallo Philip,
I am asking this question after an exhausting searched through the web.

I saw a phenomenon in which the sky where covered in a totally unified layer of clouds and the moon was placed in a "hole" in this unified layer. There was a PERFECT circular hole and the moon was set in the exact center of it. The radius of this "hole" was about 20 times the radius of the moon from where I saw it. I would also like to mention that there was neither eclipse nor halo. I am completely sure of it.

My friends how where with me noticed the exact same phenomena, also my mom who was in a mile away from me at that time.

My location was north Israel; it was about a few months ago at ~22:30 PM.

I noticed that about a year ago, you were asked a very similar question by a gay named Binh.
Here is the link to his question:
http://en.allexperts.com/q/Astronomy-1360/Cloud-ring-surounding-moon-1.htm

As I mentioned above, I am absolutely sure that there was no halo and no eclipse. What could it possibly be?

As a physics student I am positively sure that a satisfying answer does exist. It was too beautiful and terrifying to be just a lowly coincidence.

Please answer my question, I could not let this phenomena be accepted and forgot without an explanation.

Sincerely yours,
David

Answer
Hello,

Again, the only explanation I can come up with is a 22 degree lunar halo phenomenon, along the lines I explained to Binh. Under certain aspects (e.g. plate IXb in Minnaert's 'Light and Colour in the Open Air') it *does* appear the Moon is at the center of a mammoth "hole".

You mentioned about "20 times the radius of the Moon". Well, given the Moon is about a half degree in angular size, and a 22 degree halo would extend out about 11 degrees in annular radius, it would appear about twenty times bigger to your eye.

Another "giveaway' to this phenomenon, as Minnaert notes (p.190) is it typically occurs in Spring and in low humidity conditions.

Anyway, if this isn't satisfactory, you may wish to try to get hold of an expert in atmospheric physics. My specialty is solar physics, not atmospheric physics.

Hope this helps!