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A Ring Around The Moon

Unlike Saturn, which has actual, physical rings, the ring you can sometimes see around the moon is merely an optical illusion.

ring around the moon

Photo: finnur.malmquist (flickr)

Meteorologists call the ring sometimes seen around the moon a "halo effect," because diffracted light rays create a halo around a bright object.

You’ve seen pictures of the planet Saturn, surrounded by its system of rings, but would you be surprised if you looked up at night to see a ring around the moon?

In fact, it’s sometimes possible to see just this. There’s even a folk rhyme about it: When there’s a ring around the moon, rain or snow is coming soon. Is there really, sometimes, a ring around the moon?

An Optical Illusion

Unlike Saturn, which has actual, physical rings, the ring you can sometimes see around the moon is merely an optical illusion.

It’s an effect of our own atmosphere that meteorologists call a “halo effect,” because diffracted light rays create a halo around a bright object.

How It Works

Moon halos are caused by tiny ice crystals that have gathered twenty thousand feet above the ground, as thin, wispy clouds. These clouds are so thin, you might not notice them at night, if it weren’t for their effect on the moonlight. Incoming light rays from the moon are bent, or diffracted, by these ice crystals at an angle of 22 degrees.

This means that in addition to the direct moonlight, you will also see diffracted moonlight in a circle 22 degrees away from the moon. This is about the distance of your fist, held at arm’s length.

Like a rainbow, this halo can even be slightly colored; red on the inside, and blue on the outside.

Yes, it can mean that rain or snow is coming soon. Those high, wispy clouds could be the forerunners of storm clouds right behind them.

  • http://pulse.yahoo.com/_UBC27IZBMYVXPRSU3CT4ZT44WQ Diz Mex Stepn Out Of Tex

    checking it in bloomington indiana what a trip

  • donna garcia

    seeing it in san antonio, beautiful

  • http://pulse.yahoo.com/_MFSJD7WO6XQDFDUTTGHE6MMA5Y xXCooookiess!Xx

    here in indiana!

  • http://pulse.yahoo.com/_PPO6P3X2IYD35JQD25MBMH4PTY Brandy

    Saw this @ 10:40 i was out with my dogs and i sent out a text to like 50 people to go check it out as well so amazing. London ohio

  • Anonymous

    wish they would say what bad weather has happened in the past!  its beautiful!  completely amazing! seeing it in south lebanon ohio for hours now!

  • Anonymous

    wish they would say what bad weather has happened in the past!  its beautiful!  completely amazing! seeing it in south lebanon ohio for hours now!

  • http://twitter.com/Jolynn_14 Jolynn!:)

    My dad walks outside the house says its really bright and looks up and sees a ring around the moon first time seeing this and just thought that it was beautiful!!!!

  • http://profile.yahoo.com/_HSDXKQWVAXCGWCACTBQEOYFY3E Dina

    OH WOW I JUST WENT TO TAKE THE TRASH OUT TONIGHT AND WAS LIKE ITS LIGHT OUTSIDE FOR IT TO BE 10:00 AND THEN I NOTICE A RING ROUND THE MOON IT WAS SO PRETTY KINDA EPIC I CALLED MY 8 YR OLD SON OUT TO LOOK AND EXPERIENCE THIS WITH ME SO BEATIFUL LOVED IT ( SAW THIS FROM JOHNSTOWN,PA)

  • http://profile.yahoo.com/MNESNL2PFPKPONRCMK2XVIZHP4 JAMIE B

    CHEMTRAILS CHEMTRAILS CHEMTRAILS  CHEMTRAILS CHEMTRAILS

     THEY SPRAY YOU LIKE A ROACH FOR THEY FEEL YOU ARE FAR LESS THAN THAT

  • http://profile.yahoo.com/CMKI5THCJKVDGHYJECSMH36PUI Diamonary

    saw it while i was taking tha trash out thought the world was coming to an end little brother thought planets were falling haha. HOUSTON TEXAS

  • http://profile.yahoo.com/DDZ4OPJI6BMIHKMF63KKLDQDNY sunny

    hello, here in CALIFORNIA

  • PumkinPie14

    Was out with my friends tonight at the park. Saw it.. It is beautiful. My friends think its good luck. Had the best night ever. (:
    OVERLAND PARK, KS

  • racingkid1

    I just saw it and showed my mom too. It’s frakkin awesome!
    MARENGO, IL

  • http://profile.yahoo.com/SGYDG2AWVZ7D63FK452DT26YI4 Sarah Shelton

    New Halo effect on Oct. 30 2012 in Columbus IN. It is beautiful!

  • neverendingdreams07

    It is awesome tonight, I have never seen a ring around the moon that big! 

  • http://www.facebook.com/krasimira.valkanova KrasiMira ValkaNova

    I saw it today for a first time here in eastern europe….wow
    mesmerizing…
     

  • Haley Marie

    I saw it tonight in Northern U.S. Definately spooky, yet totally worth freezing your butt off! One of the coolest things I’ve seen my entire lifetime.

  • Valarie Wasson

    There’s a huge, beautiful ring around the moon tonight!

  • http://profile.yahoo.com/GQDLB4QCDJ2W7WO2VCEYSG2XV4 Gods Child

    I saw it too and I asked  my family to come outside to see it the little ones were amazed :O
    and it happen on Christmas eve O:)

  • http://profile.yahoo.com/BP47FYQVKMX2DLJRKFT6MH4ECA CookieMonstersGirl

    I am here in denton NC and we can see it clear as a bell this amazing sight of the ring around the moon!!

  • tlwalden07

    Same here in Asheboro, NC. It is very beautiful. My son had me to go outside to look at it, and I called the rest of the family. Wonder what weather is on the way?

  • anthony

    her now in philippines so beautiful :)

  • Anubhav

    Here in Amritsar,India theres a Halo Effect seen… Awsum…!

  • shadieladie32

    I saw it a couple nights ago with my boyfriend and it was beautiful. It was a full circle around it. I tried to get other people to see but no one else. So we figure it was meant for us.

  • http://www.facebook.com/kayla.morris1 Kayla Maughan

    just seen the ring around the moon. it was fasinating

  • http://www.facebook.com/scott.rusbatch Scott Warren Rusbatch

    I’m in New Zealand and I just saw the halo effect, it looks awesome.

  • ozatasmay

    From my tarrace i saw it in India.

  • HAKURU_15 NETWORKS

    the answer is very simple: forerunners

  • tripti

    halo effect

  • Narayana Bhargav

    halo effect today in mysore,
    karnataka,india

  • Manu Nair

    halo effect today in thrissur kerala

  • Mary

    saw this tonight (10/9/14) in tuscaloosa, alabama. i do not believe it was 22 degrees tho, looked much larger.

  • Mike Jones

    Saw this tonight. 12/7/14. Robertsdale, Al. Pretty Cool..

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