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Thread: Seeking a decent optical explanation for how we saw 2 crescent moons last night

  1. #1
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    Question Seeking a decent optical explanation for how we saw 2 crescent moons last night

    Hello there - and HELP

    First of all - we are both OLD scientists and use to KNOWING --- so this is driving us crazy.

    Last night when I looked up at the thin crescent moon (harvest moon color) - I saw two overlapping images. Now - did I say we are OLD? Anyhow - I thought it was my eyes. (I am a Biophysicist - I look to biology). Then my husband said to me - "Do you see TWO images of the moon up there???"

    At that point we knew it was physics and not biophysics where the answer was to be found. But this husband that I have had for 42 years (did I mention we are OLD?) - he has a doctorate in physics and has been teaching all that time and he is use to figuring out answers to all the odd questions he gets from his students. And he can not develop a satisfying explanation - backed up by science facts - for what we saw.

    On the internet I found two other times when people saw two crescent moons -
    1. one was on a blog and it occured in 2005 in St Louis.
    2. the other was in 2005 (different day and in Washington state) and it was reported right here on BAUT. (But no one seemed to give any explanation except "mirage" and no detailed "the light beams go here and here because of this and that gives you two images and you will always see it when these conditions exist.")

    Which is how I found this forum on "Q&A" which tells me that my space and astronomy questions will be answered.

    I sure to hope so.

  2. #2
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    This explanation was give in the old thread: Mirage

    http://en.wikipedia.org/wiki/Mirage

    Scroll down to the sections Inferior and Superior Mirage.

    BTW, Welcome to the forum. If "Mirage" isn't the correct answer then someone here will know what the correct answer is.

  3. #3
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    Welcome, Donna and David... All very good explanations require the fullest of scrutiny...
    This 'Wickie' article link supplied by Tuscon Tim is the most logical explanation and I would buy into it as the best bet...
    but... How late after sunset? what atmospheric conditions between you and said target, the moon. Lets face it we know there is but one moon so its only the light path refraction that could cause this double image. Were you looking through glass? A whole new set of elements arises if you were. Just thinking about this is good for my mind, thank you. I hope we are helping...

  4. #4
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    How far apart were the images; how much did they overlap?

    A mirage generated by the air would normally not hold still; it would be wavy.

  5. #5
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    Quote Originally Posted by Delvo View Post
    A mirage generated by the air would normally not hold still; it would be wavy.
    Check out the wiki entry: Superior Mirage. It states that they can be more stable.

  6. #6
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    I think one diagnostic feature for mirage would be whether the images of the moon were stacked one above the other close to the horizon, or not.
    If they were side by side, then we probably have a problem using "mirage" as an explanation. Also, the higher above the horizon the effect appeared, the less likely you are to be seeing a mirage.

    (And, since you are OLD, I am forced to ask if you both happened to be wearing bifocal lenses. )

    Grant Hutchison

  7. #7
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    Were you seeing pairs of anything else that night? Just two cressent moons?

    I'm thinking a crazy temperature inversion caused a couple layers of atmosphere to refract the moons light funky. I'd think you'd see some double stars around it too though since you say it was just a couple slivers of the moon. My super scientific explination.

    It didn't look like ( ) that did it? Or more like ))?

  8. #8
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    You wouldn't necessarily see doubled stars, if one mirage image was desaturated compared to the other. The stars might then drop out of visibility, while the crescent moon would still be visible, only fainter.

    Grant Hutchison

  9. #9
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    Talking equally old

    Donna. You learn something everyday. Never heard of it till now.thanks

    There is a neat trick with Iceland Spar though,,(calcium carbonate crystals). They do double refraction....take a piece of paper, put one small dot on it with a pencil, ask somebody how many dot's there are, hold up the clear spar for them to look through, then place it over the dot...now there's two.
    It separates the light into two polarization planes, if you rotate the crystal over the dot, one moves, the other doesn't, if you get a piece of polaroid, one disappears the other doesn't....fun.

  10. #10
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    The first question should be: What planet do you live on?

    If Donna and Dave live in a different solar system, two crescent moons could appear on a regular bases...
    It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. ― Arthur Conan Doyle, Sherlock Holmes

  11. #11
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    Were you near the ocean?

  12. #12
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    Question

    is it possible an metal alloy was giving off light from the sun


    but couldnot be detected or any such?

  13. #13
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    I think I have seen the same thing. Was it two images of the cresent moon nested in one another and almost overlapping? I thought it was my glasses, but I am nearsighted, so I could barelly tell there was a moon when I took them off.

    Thing is, I had the same thing happen with my alarm clock. Its a digital display, and I could see two images if the numbers overlapping one another. This I could see without my glasses, but the doctor I went to the next day couldnt find anything wrong (wasnt seeing double then either).

    I have a couple possibilities if you are seeing the same thing.

    I think it is biological since I saw it in more than one place.
    It could be caused by looking at a really bright light. I think this cause one time I saw this was after driving a couple hours with no sunglasses, and another was when we were running some really bright argon plasma.

    My other theory is it may have been some wierd side effect of diabetes. Problem is I dont know how long I have been diabetic.

    Hope this helps

  14. #14
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    Post

    The diabedeas thing could be true my dad just died from it and i know his vision he said was blury and sometimes saw two of 1 thing but i dont know how long hes had it.




    the problem is this only hapened to him 2 times if i remembered right
    becaus it was from when we get back from vacation he seems to go through the symptums of diabetes
    Last edited by liflessdreamer; 2007-Aug-20 at 08:50 PM. Reason: inserting sentences

  15. #15
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    Seriously, there is a good possibility that what you witnessed was like a Fressnel lensing effect due to one or more inversions in the the atmosphere along the line of sight. Just as the bottom of clear lake is displaced by the refractive index at the surface, the true location of the moon and stars can be slightly displaced when there is a sudden change in the temperature of an air mass.

    I would also suspect this would more likely happen during a crescent moon, than a full one, because the solar disruption/shearing of the atmosphere is more likely ~40 degrees from the sun than the 180 deg angle of a full moon.
    It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. ― Arthur Conan Doyle, Sherlock Holmes

  16. #16
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    Mirage both types

    I think it might be as in the picture I am going to try and attach. I think this scenario qualifies for both types of mirage that the Wiki article refers to.


    [IMG]file:///C:/Documents%20and%20Settings/cgraham/My%20Documents/My%20Pictures/2007-08-30/Save0209.JPG[/IMG]
    Attached Images Attached Images

  17. #17
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    These might seem obvious questions, but-

    were you observing through a window? Internal reflections can cause double images, especially when looking through double glazing.

    If outside, was there a chill wind blowing? In which case the answer might be biological after all- a slight wind can make the eyes water, leading to double images. If I am cycling at night, I often see double images of stars or planets and so on until I clear the water from my eyes. Blinking is not always enough.

  18. #18
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    I have to ask... Had you both been drinking? Were your eyes crossed? This produces double vision, but would be noticeable as everything would be double.

    On the more serious note, other substances can cause slight doubling of the vision, most notable when looking at more distance objects. Some things found in certain foods (kava) can relax a person enough to the point where their eyes are undergo what's called exaggerated convergence (cross-eyedness), which, of course, produces two images.

    However, to give you folks the benefit of the doubt, I agree that it was probably just a sharp change in the atmosphere along the line of viewing (density) which produced a very slight double image.

  19. #19
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    Here's another sighting, supposed at 60 degees altitude!

    Here's another actual photograph
    at sunset that shows a slight hint at a double image trying to form.

    This one looks like the camera was jostled, but maybe its real.

  20. #20
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    Guess I am not the only one

    Hey Donna and David,
    I thought I needed to go to doctor to get my eyes checked when I saw two crescent moon. I looked at it with my right eyes shut and I saw two crescent and tried it with other eye and I saw two crescent. Then I looked at stars but they were not overlapping. I thought I was going crazy and then searched internet and here I am. Well, now that I know that it's some physics I am glad I am not crazy. Thanks for posting this!
    Quote Originally Posted by Donna and/or David View Post
    Hello there - and HELP

    First of all - we are both OLD scientists and use to KNOWING --- so this is driving us crazy.

    Last night when I looked up at the thin crescent moon (harvest moon color) - I saw two overlapping images. Now - did I say we are OLD? Anyhow - I thought it was my eyes. (I am a Biophysicist - I look to biology). Then my husband said to me - "Do you see TWO images of the moon up there???"

    At that point we knew it was physics and not biophysics where the answer was to be found. But this husband that I have had for 42 years (did I mention we are OLD?) - he has a doctorate in physics and has been teaching all that time and he is use to figuring out answers to all the odd questions he gets from his students. And he can not develop a satisfying explanation - backed up by science facts - for what we saw.

    On the internet I found two other times when people saw two crescent moons -
    1. one was on a blog and it occured in 2005 in St Louis.
    2. the other was in 2005 (different day and in Washington state) and it was reported right here on BAUT. (But no one seemed to give any explanation except "mirage" and no detailed "the light beams go here and here because of this and that gives you two images and you will always see it when these conditions exist.")

    Which is how I found this forum on "Q&A" which tells me that my space and astronomy questions will be answered.

    I sure to hope so.

  21. #21
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    Hi PuzzledBrad, welcome to Cosmoquest. It's not a problem, but you're responding to an almost 7 year old post, and the original poster hasn't been here since 2008 (when we were still at bautforum.com).
    ____________
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    "Your right to hold an opinion is not being contested. Your expectation that it be taken seriously is." -- Jason Thompson
    "This is really very simple, but unfortunately it's very complicated." -- publius

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  22. #22
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    It's too bad the original poster didn't return and say how
    high above the horizon the Moon was, and whether the
    double images were stacked vertically or in some other
    orientation.

    -- Jeff, in Minneapolis

  23. #23
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    On Friday nigh 8/29/14, while driving east of Pittsburgh, PA around 9:30 PM, we saw what appeared to be two crescent moons. One was large and the other was much smaller. (I would compare it to a silver dollar and a pencil top eraser.) It looked like the smaller body was orbiting in front of the the larger one, much like what happens during an eclipse. (The smaller body was near the front edge of the larger body.) They were bright enough to clearly define both shapes. I called the local TV station and the weatherman offered an explanation of ice crystals and halos. That was no halo. I'd like to know if there were any asteroids nearby? Or was this an atmospheric illusion?

  24. #24
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    karizmah,

    It was probably some kind of atmospheric effect. The fact that
    one image was much larger than the other should help a lot in
    pinning down exactly which illusion it is, but I don't know, myself.
    Different-size images are what you get with internal reflections
    in a camera lens. I don't know how else you can get them.
    An internal reflection in a flat window would be the same size
    as the unreflected image.

    -- Jeff, in Minneapolis

  25. #25
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    I wanted to add to this thread, because I just saw what Donna and/or David described for the first time and had a difficult time finding anything about it at all online.

    I searched for "double moon", "moon with appendage", "moon with tail", and "moon refraction" hoping that those keywords would work.

    I saw this phenomenon on April 27, 2017 in Nashville, TN at 8:00pm, with the moon about 45 degrees altitude.
    The moon was a very thin crescent, and a slightly overlapping, thinner crescent was below and to the right of it.

    I'd love to see some more information about this effect!

  26. #26
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    Welcome to Cosmoquest, chh. It's no problem at all to revive a 10 year old thread, especially if you're looking for an explanation for an apparently rare phenomenon.
    ____________
    "Dumb all over, a little ugly on the side." -- Frank Zappa
    "Your right to hold an opinion is not being contested. Your expectation that it be taken seriously is." -- Jason Thompson
    "This is really very simple, but unfortunately it's very complicated." -- publius

    Moderator comments in this color | Get moderator attention using the lower left icon:
    Recommended reading: Forum Rules * Forum FAQs * Conspiracy Theory Advice * Alternate Theory Advocates Advice

  27. #27
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    Having a mostly constant effect in one eye -- that still has my ophthamologist puzzled -- I had a search term to try: moon ghost image.

    Were the 2 moons of equal brightness, or was one brighter? Did it look like the ones at Cosmic Variance: Ghost Moon?, or others from hits on those terms?

    Come to think of it, on rare occasions my 2 images are of equal brightness, but usually one is a dim image, shifted up about one-quarter degree.

    I'm not saying you have my eye issue, but maybe those terms will lead you somewhere. I don't have time to investigate right now. Good luck at getting an answer. Let us know if you do.
    Last edited by 01101001; 2017-Apr-28 at 11:59 PM.
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    Skepticism enables us to distinguish fancy from fact, to test our speculations. --Carl Sagan

  28. #28
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    While I'm asking questions, the next must be about physical viewing conditions: unaided eyeball? dry? teary? both eyes? glasses? contacts? eye surgery? camera? telescope? window? time? sky? lighting? weather?

    The simplest explanation if it were just a standard-issue eyeball capturing 2 images of the moon, is some unusual air condtions that gently split the paths of photons somewhere between you and the start of space.
    0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 ...
    Skepticism enables us to distinguish fancy from fact, to test our speculations. --Carl Sagan

  29. #29
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    Maybe there was a very thick pane of glass that doubled the image.

  30. #30
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    Hi, everyone,

    Im new here and found this forum because I saw something super weird this morning, just 20 minutes ago at 6:22am Pacific Time. I live in San Jose, California. I saw a crescent moon very high up in the sky, and then a tiny crescent moon very low to the horizon between the tree tops. I was using binoculars and I wear single focal nearsighted eyeglasses. I cant see the real moon and the baby moon in the same lens area. What I mean is, when Im pointing the binoculars at the real moon, the round space that I see the real moon in is not large enough to contain the baby moon. I must move the binoculars and point them way down in order to see the baby moon, at which time the real moon has gone out of the round lens area. So, considering that Im not seeing the two moons in a single lens area, is that a mirage effect?

    Thank you,
    nonnynu

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