# What might have caused this "moon halo?" (Pics Inside) **URL:** \ **Category:** Factual Questions\ **Created:** [October 4, 2009, 5:30am UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519 "2009-10-04T05:30:36Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![Cyberhwk](https://avatars.discourse-cdn.com/v4/letter/c/7993a0/32.png) [@Cyberhwk](https://boards.straightdope.com/u/Cyberhwk)\ **Post date:** [October 4, 2009, 5:30am UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/1 "2009-10-04T05:30:36Z")
I came home from class the other night and noticed some strange halo around the moon. So I grabbed my camera to get the pictures below at various exposure levels. [Pic 1](http://img.photobucket.com/albums/v691/Cyberhwk/DSC_1657.jpg) [Pic 2](http://img.photobucket.com/albums/v691/Cyberhwk/DSC_1658.jpg) [Pic 3](http://img.photobucket.com/albums/v691/Cyberhwk/DSC_1659.jpg) [Pic 4](http://img.photobucket.com/albums/v691/Cyberhwk/DSC_1660.jpg) [Pic 5](http://img.photobucket.com/albums/v691/Cyberhwk/DSC_1661.jpg) So what the hell would have caused this? **This is not lens flare.** Or at least not from the camera, The bright dot under the moon is I think, but not the ring. I took the picture only because I noticed it through my own eyes. My only thought would be maybe the atmosphere somehow acted as a “lens” of it’s own and it was “flare” on the overcast sky, but then again I have no idea what I’m talking about. Couldn’t be a natural cloud formation. Way too uniform. 😕 ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [October 4, 2009, 5:42am UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/2 "2009-10-04T05:42:59Z")
Ice crystals in the air cause them. > **[Halo (optical phenomenon)](https://en.wikipedia.org/wiki/Halo_%28optical_phenomenon%29)** > > A halo (from Ancient Greek ἅλως (hálōs) 'threshing floor, disk') is an optical phenomenon produced by light (typically from the Sun or Moon) interacting with ice crystals suspended in the atmosphere. Halos can have many forms, ranging from colored or white rings to arcs and spots in the sky. Many of these appear near the Sun or Moon, but others occur elsewhere or even in the opposite part of the sky. Among the best known halo types are the circular halo (properly called the 22° halo), light p Th... Your pictures look a lot like the 22 degree halos in the above article. ---
**Author:** ![Cyberhwk](https://avatars.discourse-cdn.com/v4/letter/c/7993a0/32.png) [@Cyberhwk](https://boards.straightdope.com/u/Cyberhwk)\ **Post date:** [October 4, 2009, 6:34am UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/3 "2009-10-04T06:34:56Z")
That looks like it to me. Thank you. ---
**Author:** ![Zoe](https://avatars.discourse-cdn.com/v4/letter/z/a4c791/32.png) [@Zoe](https://boards.straightdope.com/u/Zoe)\ **Post date:** [October 4, 2009, 10:50am UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/4 "2009-10-04T10:50:54Z")
From the poem [“The Wreck of the Hesperus”](http://www.blupete.com/Literature/Poetry/Wreck.htm) by Longfellow: "I pray thee, put into yonder port, for I fear a hurricane. “Last night the moon had a golden ring, And to-night no moon we see!” ---
**Author:** ![Contrapuntal](https://avatars.discourse-cdn.com/v4/letter/c/e274bd/32.png) [@Contrapuntal](https://boards.straightdope.com/u/Contrapuntal)\ **Post date:** [October 4, 2009, 11:21am UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/5 "2009-10-04T11:21:20Z")
[It could be lost love.](http://www.youtube.com/watch?v=OqFfY1jFfz0) ---
**Author:** ![Henrichek](https://avatars.discourse-cdn.com/v4/letter/h/5daacb/32.png) [@Henrichek](https://boards.straightdope.com/u/Henrichek)\ **Post date:** [October 4, 2009, 11:36am UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/6 "2009-10-04T11:36:50Z")
> [@gazpacho](#): > > Your pictures look a lot like the 22 degree halos in the above article. It even has its own article: > **[22° halo](https://en.wikipedia.org/wiki/22%C2%B0_halo)** > > A 22° halo is an atmospheric optical phenomenon that consists of a halo with an apparent radius of approximately 22° around the Sun or Moon. Around the Sun, it may also be called a sun halo. Around the Moon, it is also known as a moon ring, storm ring, or winter halo. It forms as sunlight or moonlight is refracted by millions of hexagonal ice crystals suspended in the atmosphere. Its radius, as viewed from Earth, is roughly the length of an outstretched hand at arm's length. > Even though it is on... ---
**Author:** ![The\_Stafford\_Cripps](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/the_stafford_cripps/32/7167_2.png) [@The\_Stafford\_Cripps](https://boards.straightdope.com/u/The_Stafford_Cripps)\ **Post date:** [October 4, 2009, 3:29pm UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/7 "2009-10-04T15:29:57Z")
I saw one of these once when the moon was being eclipsed, which was a cool co-incidence. ---
**Author:** ![AHunter3](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ahunter3/32/368_2.png) [@AHunter3](https://boards.straightdope.com/u/AHunter3)\ **Post date:** [October 4, 2009, 5:03pm UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/8 "2009-10-04T17:03:19Z")
Less commonly, you can see them around the SUN. The ring is black when that happens. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [October 4, 2009, 7:52pm UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/9 "2009-10-04T19:52:49Z")
They occur just as commonly around the Sun; they’re just less noticeable because the glare of the Sun itself is so close. ---
**Author:** ![fiddlesticks](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fiddlesticks/32/18129_2.png) [@fiddlesticks](https://boards.straightdope.com/u/fiddlesticks)\ **Post date:** [October 5, 2009, 12:56am UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/10 "2009-10-05T00:56:59Z")
Saw those rings around the moon all the time in the winter growing up in Wisconsin. They were usually a good sign that snow was on the way in coming day or two. ---
**Author:** ![Baggins111](https://avatars.discourse-cdn.com/v4/letter/b/9fc29f/32.png) [@Baggins111](https://boards.straightdope.com/u/Baggins111)\ **Post date:** [October 5, 2009, 3:19am UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/11 "2009-10-05T03:19:35Z")
> [@Chronos](#): > > They occur just as commonly around the Sun; they’re just less noticeable because the glare of the Sun itself is so close. Sun dogs ---
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [October 5, 2009, 4:21am UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/12 "2009-10-05T04:21:20Z")
FWIW…as I type this (Monday morning, 12:20 AM, Atlantic City area) there is a halo around the moon just a you have pic-ed in the OP. ---
**Author:** ![Serenata67](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/serenata67/32/10646_2.png) [@Serenata67](https://boards.straightdope.com/u/Serenata67)\ **Post date:** [October 5, 2009, 12:23pm UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/13 "2009-10-05T12:23:02Z")
> [@fiddlesticks](#): > > Saw those rings around the moon all the time in the winter growing up in Wisconsin. They were usually a good sign that snow was on the way in coming day or two. I remember that’s why my parents always told us. Kinda surprisingly, though. My mom’s a doctor (biologist) and my dad’s a physicist. And I don’t think the halo-snow coincidence is supported by any hard science. _Or is it?_ ---
**Author:** ![Lanzy](https://avatars.discourse-cdn.com/v4/letter/l/74df32/32.png) [@Lanzy](https://boards.straightdope.com/u/Lanzy)\ **Post date:** [October 5, 2009, 3:30pm UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/14 "2009-10-05T15:30:27Z")
I was always told this means its going to rain. ---
**Author:** ![Anne\_Neville](https://avatars.discourse-cdn.com/v4/letter/a/b9e5f3/32.png) [@Anne\_Neville](https://boards.straightdope.com/u/Anne_Neville)\ **Post date:** [October 5, 2009, 4:15pm UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/15 "2009-10-05T16:15:33Z")
> [@Serenata67](#): > > I remember that’s why my parents always told us. Kinda surprisingly, though. My mom’s a doctor (biologist) and my dad’s a physicist. And I don’t think the halo-snow coincidence is supported by any hard science. _Or is it?_ The halo is caused by ice crystals in cirrus clouds. There are often a lot of cirrus clouds in front of storm systems. An oncoming storm produces conditions that are favorable for halos. In the winter in Wisconsin, my understanding is that a storm system is more likely to produce snow than rain. ---
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [October 5, 2009, 9:26pm UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/16 "2009-10-05T21:26:34Z")
You say the blue dot is a lens flare; yet, why is it in different locations in the consecute photos? I guess I am assuming the photos were taken back-to-back. …Did you take the moon photos at different times of the night? ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [October 5, 2009, 11:25pm UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/17 "2009-10-05T23:25:15Z")
> [@](#): > > > [@](#): > > > > : > > Originally Posted by Chronos > > They occur just as commonly around the Sun; they’re just less noticeable because the glare of the Sun itself is so close. > > Sun dogs Not quite – there’s a subtle but profound difference between a 22 degree halo and a sun dog. The halo is caused by randomly oriented crystals, with the rays passing between faces that make a 60 degree angle with each other. (Usually these are the non-adjacent faces of hexagonal rods or plates, but there ARE cases where the plate has an equilateral triabgle cross-section). Sun dogs are caused by plates (or, rarely, hexagonal rods) that are oriented so that the hexagonal cross=section is horizontal. Hence, they appear as blobs of light on either side of the sun (if there happen to be ice crystals there). When the sun is on the horizon, the sun dogs lie right on the 22 degree halo. But as the sun rises, the sun dogs start to move _outside_ the 22 degree halo, always remaining level horizontally with the sun. They are rarely seen above a few tens of degrees, and they vanish above 40 degrees due to total internal reflection. You can get lunar equivalents of sun dogs – called "moon dogs’ or “paraselenae”, but they’re much rarer. Sun dogs, on the other hand, are incredi9bly common. They’re more common than rainbows, although most people don’t know to look for them. ---
**Author:** ![Cyberhwk](https://avatars.discourse-cdn.com/v4/letter/c/7993a0/32.png) [@Cyberhwk](https://boards.straightdope.com/u/Cyberhwk)\ **Post date:** [October 6, 2009, 8:19am UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/18 "2009-10-06T08:19:37Z")
> [@Jinx](#): > > You say the blue dot is a lens flare; yet, why is it in different locations in the consecute photos? I guess I am assuming the photos were taken back-to-back. …Did you take the moon photos at different times of the night? Not really, but I did have to reset the camera every time I took a picture. So I assume the angle wasn’t exactly the same every time. ---
**Author:** ![Floppy\_Joe](https://avatars.discourse-cdn.com/v4/letter/f/3bc359/32.png) [@Floppy\_Joe](https://boards.straightdope.com/u/Floppy_Joe)\ **Post date:** [October 6, 2009, 6:42pm UTC](https://boards.straightdope.com/t/what-might-have-caused-this-moon-halo-pics-inside/512519/19 "2009-10-06T18:42:06Z")
This is a Sun Halo. I took this back in May 2002… [Sun Halo](http://raineyranch.mrainey.com/gallery/albums/userpics/10002/normal_SunRing1.JPG)