Moon double-image

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Herman
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Moon double-image

Postby Herman » Sat Jan 05, 2008 8:09 pm UTC

Perhaps like some other people here, I have aquired a reputation in my family as the Science DudeTM. So when my Grandma asked me about this, I couldn't let her down, but I couldn't find any good information on it either.

Anyway, Grandma reports that she saw a double-image of the moon yesterday in the early morning. One image was to the south and closer to the horizon than the other. Beyond assuring her that the moon doesn't come apart as a rule, I had no explanation. There's a reference to double-refraction in my optics textbook, but that only happens when the object is seen through two materials with different polarization axes. But air definitely isn't a crystal; there's no polarization going on. I also read up on mirages, which are caused by the different refractive indices of warm and cold air. But a mirage is just one image -- you don't see a copy of something, just something in the wrong place. Anyone know something about this?

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Re: Moon double-image

Postby skeptical scientist » Sat Jan 05, 2008 8:24 pm UTC

I have nothing. Atmospheric refraction could explain a mirage, but typically atmospheric refraction only takes place in an up-down direction, so one image would not appear south of the other. Furthermore, there would also be a great deal of distortion making it fairly clear what's going on, and a distinct double image would probably be quite impossible.

(You can find a lot of cool info about atmospheric optics at www.atoptics.co.uk, but I don't think there's anything there which would explain it.)

Had she perhaps been drinking? :P
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Herman
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Re: Moon double-image

Postby Herman » Sat Jan 05, 2008 8:40 pm UTC

I have nothing. Atmospheric refraction could explain a mirage, but typically atmospheric refraction only takes place in an up-down direction, so one image would not appear south of the other. Furthermore, there would also be a great deal of distortion making it fairly clear what's going on, and a distinct double image would probably be quite impossible.


I wouldn't regard the direction of the displacement of the image as a deal-breaker. She might have been mistaken, or I misheard her, or something. Ditto for distortion. The main thing is: can a mirage produce double images?

Edit: Distortion within reason, of course. A small amount is consistent with her observation, but she did say that both moons were crescent, so there couldn't have been that much distortion.

Also, she mentions that there was no window in the way.

Had she perhaps been drinking?


That hypothesis is similar to the Strong Anthropic Principle, in that it is philosophically valid, but as scientists, we are forced to ignore it since to assume it true would be to abandon our quest for knowlege as futile. :P

But I will look into her opthamological history...

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Re: Moon double-image

Postby yy2bggggs » Sat Jan 05, 2008 9:07 pm UTC

Herman wrote:Anyway, Grandma reports that she saw a double-image of the moon yesterday in the early morning. One image was to the south and closer to the horizon than the other.

It sounds like a moon dog to me (slap that, quoted, in google images).
But air definitely isn't a crystal

But air very commonly contains crystals.
Image

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Re: Moon double-image

Postby skeptical scientist » Sat Jan 05, 2008 9:27 pm UTC

yy2bggggs wrote:
Herman wrote:Anyway, Grandma reports that she saw a double-image of the moon yesterday in the early morning. One image was to the south and closer to the horizon than the other.

It sounds like a moon dog to me (slap that, quoted, in google images).

Yeah, that actually sounds possible now that you mention it was a crescent moon, since moondogs (and sundogs) are crescent shaped. For some reason I was picturing a full moon. But I'm not sure if a crescent moon would be bright enough to create visible ice halos since it's so much dimmer than a full moon.

You can find more info about sundogs at the atmospheric optics site I linked above. Does your grandmother live a northerly area? If not, we can probably rule out moondogs, but if so, it might be a possibility, but I think it's a weak one.
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Re: Moon double-image

Postby Herman » Sun Jan 06, 2008 5:15 am UTC

She lives in a beach resort town in southern New Jersey. Couple interesting things about this location:

1. There was a cold front from Canada going through the area right around then (= ice crystals in the upper atmosphere).
2. The town is virtually deserted in the winter (= no light pollution).

So... possibly it's a moondog? If so, cool! Thanks, guys.

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Re: Moon double-image

Postby antonfire » Sun Jan 06, 2008 5:28 am UTC

Alternate theory: Was your grandmother wearing glasses? Could that account for it?
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Re: Moon double-image

Postby M.qrius » Sun Jan 06, 2008 10:12 am UTC

antonfire wrote:Alternate theory: Was your grandmother wearing glasses? Could that account for it?

Unlikely. If someone is wearing glasses, and sees a second moon, he's going to want to look at it more closely: through his glasses.

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Re: Moon double-image

Postby Herman » Sun Jan 06, 2008 10:00 pm UTC

No, I don't think she was.

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Re: Moon double-image

Postby GinaLynn » Tue Feb 05, 2008 12:42 am UTC

Hi. This observance didn't happen recently, and I apologize for that. However, I thought that you guys might still find this interesting.

I was on picket duty in late October, 1995, when I saw something I will never forget. Around 10:00 a.m. I happened to look straight up in the sky and saw the moon. It appeared very large and was about 3/4 full (sorry, I don't know the proper term). After staring at it for a couple of minutes, it occurred to me that it was in the wrong part of the sky. That's when I looked southward, towards the horizon and saw it again. I did a double-, triple-, quadruple-take! I couldn't believe my eyes. I did a comparison and the moons were identical.

I was alone that day. picketing a less-used back entrance to Fred Meyer main office, in Portland, OR. I couldn't believe my luck - that day there was noone there to back me up as to what I was seeing! I even tried to stop a couple of bicyclists to get them to stop and look up to see what I was seeing. I guess they figured I was crazy since they wouldn't stop for me.

I continued to look back and forth, at the moon in the sky above and the one at the horizon. Until it made me dizzy. I kept expecting the one overhead to disappear. After awhile, I guess I got tired of looking at them, especially with noone to discuss them with. My attention wandered and before I knew it, it was afternoon and my husband was picking me up. I looked for the moons, but, of course, they were gone. He didn't believe that I had really seen what I had seen.

So that was that. Every so often, I Google the internet looking for any mention of two moons being sighted in the sky at once. This is the second one that I have found. The first one was about a double crescent moon (http://www.bautforum.com/astronomy/1623 ... post352187). Your sighting is closer to mine but different because of the difference in amount of separation of moons. The fact that the second moon was straight up made me think it was some kind of atmospheric reflection or mirage phenomenon.

Let me know what you think of my experience, okay?

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Re: Moon double-image

Postby Herman » Tue Feb 05, 2008 1:03 am UTC

Cool! First independent personal description I've heard. Thanks, and thanks for the PM. Might've missed it. Glad to know this is real, and tickled to know it's pretty rare.

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Re: Moon double-image

Postby 3.14159265... » Tue Feb 05, 2008 4:09 am UTC

If this observation happened 1400 years ago ish we should all become Muslims.
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Re: Moon double-image

Postby Johnny B. » Wed Mar 19, 2008 8:14 pm UTC

During the recent lunar eclipse I witnessed a similar thing. As the moon was coming out of eclipse, a second moon appeared just to the left and below the moon. It was bluish green and a reverse image of the moon. Over the next few minutes it migrated farther away from the moon. Then the clouds rolled in and, for me, the eclipse was over. I sent a photo to an astronomer who shared it with colleagues and they all want to tell me that it was an artifact of the camera. But I could see it plainly with my naked eyes, so that can't be it. I am convinced that it was caused by some sort of atmospheric condition, but I don't know what. I wasn't drunk and I'm not a member of the aluminum foil helmet crowd. I will try to contact a meteorologist and if I learn anything useful, I will post it.

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Re: Moon double-image

Postby skeptical scientist » Wed Mar 19, 2008 8:31 pm UTC

Johnny B. wrote:During the recent lunar eclipse I witnessed a similar thing. As the moon was coming out of eclipse, a second moon appeared just to the left and below the moon. It was bluish green and a reverse image of the moon. Over the next few minutes it migrated farther away from the moon. Then the clouds rolled in and, for me, the eclipse was over. I sent a photo to an astronomer who shared it with colleagues and they all want to tell me that it was an artifact of the camera. But I could see it plainly with my naked eyes, so that can't be it. I am convinced that it was caused by some sort of atmospheric condition, but I don't know what. I wasn't drunk and I'm not a member of the aluminum foil helmet crowd. I will try to contact a meteorologist and if I learn anything useful, I will post it.

Can you post the picture too?

(I will allow a picture of this, even though you've only got one post, since it would be interesting and relevant to the topic and you seem not to be a spammer. - gmalivuk)
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Re: Moon double-image

Postby Johnny B. » Fri Mar 21, 2008 6:26 pm UTC

I'm fairly inexperienced with online forums. What is an acceptable file size, and is jpeg the best format?

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Re: Moon double-image

Postby gmalivuk » Fri Mar 21, 2008 8:33 pm UTC

For file size, try to keep it on the order of 100KB, I'd say. Also, say, no bigger than 800x600 if you're going to post it right in here. If you have a much higher-quality image that takes up more memory than that, link to it from a smaller picture. JPEG is acceptable.
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Re: Moon double-image

Postby skeptical scientist » Sat Mar 22, 2008 3:57 am UTC

gmalivuk's edit wrote:(I will allow a picture of this, even though you've only got one post, since it would be interesting and relevant to the topic and you seem not to be a spammer. - gmalivuk)

Good point - I completely forgot about that rule, sorry.
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Re: Moon double-image

Postby gmalivuk » Mon Mar 24, 2008 5:57 pm UTC

skeptical scientist wrote:
gmalivuk's edit wrote:(I will allow a picture of this, even though you've only got one post, since it would be interesting and relevant to the topic and you seem not to be a spammer. - gmalivuk)

Good point - I completely forgot about that rule, sorry.

No problem at all. It's not your job to make sure others adhere to every rule we've got. I just figured I'd mention that a moderator was okay with it, since sometimes people don't post links that would actually be useful and helpful because they did know about the rule and worried about breaking it.
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Re: Moon double-image

Postby Nebulae » Tue Mar 25, 2008 5:42 am UTC

It's just a cloaked death star in orbit. Don't worry about it.

Honestly though, that's really cool. I wonder if you had a telescope, if you'd be able to discern the cause of the moon image.

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Re: Moon double-image

Postby xsitement » Fri Oct 21, 2011 12:56 am UTC

I found your forum searching for a simular experience. My older brother and I both saw it in the early morning hours of sunrise while delivering papers one Sunday morning, 1974. Just as the sun was about to rise in the eastern sky, the moon was just about above and there was this large "planet or moon" (compared to the largest full moon I have seen, my brother and I say conservitivly 4 to 8 times larger. I remember seeing the surface of the object very distinctly and it glowed an ugly red. It appeared so close that we thought it was crashing into Earth. It remained in the sky for about 30 min as we completed our route, we did not want to even walk in the direction of the object but forced ourselves to deliver in that direction. Once we arrived home in complete fear and told our Mom, who reacted like any parent with little kids. The object was gone once the sun was up and everything else in the sky was out shined. It was not Mars, it was not the moon, I cant think of a position where an atmopheric condition would mirage and magnify the moon's image. Also the face of the moon is very recognisable, we usually see the same side, and what we saw did not have same surface, once again, it was so large and close in the morning sky, I could see clear detail of the poc marked surface and the glowing red hue. We never discussed it after that, just once in a while my brother and I reflect and think it was something extraordinary we experienced. Has anyone ever seen such an anomoly and anyone have speculation?

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Re: Moon double-image

Postby iChef » Fri Oct 21, 2011 4:52 am UTC

That's no moon......
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Re: Moon double-image

Postby gmalivuk » Fri Oct 21, 2011 12:02 pm UTC

xsitement wrote:Has anyone ever seen such an anomoly and anyone have speculation?
One of my personal speculation is: it was the moon, or an image of the moon. Because I do not believe that you remember the viewing conditions from a night more than 35 years ago well enough to actually determine that there's no way it was the moon or an image/mirage of the moon.

Another possibility is that it was a cloud being lit up by the still-below-the-horizon sun.
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Re: Moon double-image

Postby cpt » Fri Oct 21, 2011 1:04 pm UTC

What ever happened to that picture that was supposed to be posted? Was it removed after ~3 years, or just never posted?

EDIT: After using my brain, Johnny B's post count answers that one.

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Re: Moon double-image

Postby Bobster » Thu Mar 08, 2018 2:04 pm UTC

I witnessed a similar crescent moon double image. The moon was setting, about 20 degrees above the horizon, and was late summer in Maine, 2017. The crescents overlapped slightly, one above the other with the lower one slightly offset to the left. It was a cool evening, not yet dark, but there was reported to be a layer of warm air above what we were experiencing. Originally I saw it while driving, but stopped and saw it again while not looking through the car's glass. I also saw it both with and without glasses on. Had not been drinking. And my wife saw the exact same thing as I did. It lasted about 20 minutes and then was gone. I did take a photo with my phone camera, but that showed no sign of the second moon image.


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