Look at the Perfectly Circular Moon Shining Through the Clouds!

[relativelyslow]

11/23 10:41. the moon is shining through a circular opening in the clouds or something. seriously, the opening is a perfect circle. it is the weirdest thing!go look at it! what the heck?

 

[relativelyslow]

its actually not just an opening in the clouds; its like a ring! outside the ring i see stars and stuff so its not continuous cloud cover with an opening. i assume they are clouds because i don't know what else the light would reflect off of. does anyone know what's going on? this is the coolest thing

 

[russ_watters]

Ice crystals in the upper atmosphere this time of year act as prisms and re-direct the moonlight toward you. There are actually two possible rings at 22 and 44 degrees from the moon: http://home.hiwaay.net/~krcool/Astro/moon/moonring/

 

[Labguy]

its actually not just an opening in the clouds; its like a ring! outside the ring i see stars and stuff so its not continuous cloud cover with an opening. i assume they are clouds because i don't know what else the light would reflect off of. does anyone know what's going on? this is the coolest thing

Check out 12.2 on this link:
http://www.auf.asn.au/meteorology/section12.html
Lots of other neat stuff there too.

 

[relativelyslow]

thats cool. it seems kind of arbitrary that the radius of the circle around the moon is what it is. what do you mean two possible rings at 22 and 44 degrees? its hard to imagine ice crystals in florida but i suppose it is cold at that altitude.

 

[Entropy]

Yeah I noticed that too! First I thought it was just clouds but it was a clear night. I live in Florida and noticed it while grilling beer waursts with my dad.

 

[russ_watters]

thats cool. it seems kind of arbitrary that the radius of the circle around the moon is what it is. what do you mean two possible rings at 22 and 44 degrees? its hard to imagine ice crystals in florida but i suppose it is cold at that altitude.

Two things: the spacing of the rings is determined by the shape of the ice crystals and air gets a degree or two colder for every 1,000 feet of altitude.

 

[turbo]

thats cool. it seems kind of arbitrary that the radius of the circle around the moon is what it is. what do you mean two possible rings at 22 and 44 degrees? its hard to imagine ice crystals in florida but i suppose it is cold at that altitude.

The spacings are actually 22 degrees (light entering a side facet of an ice crystal and exiting through another) and 46 degrees (light entering a side facet and leving through an end facet, for instance). Those of us who live in the higher latitudes probably get to see more halos and more types of them than you Southerners. Here is a very comprehensive website on halos:

http://www.sundog.clara.co.uk/halo/halosim.htm

It explains how halos, arcs, sundogs, pillars, etc form.

 

[mbeeston]

so that's what that was, i was wondering about it :)