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Archive 2013 · Moon's Heading. The Doppler Effect?
  
 
OldProf
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p.1 #1 · p.1 #1 · Moon's Heading. The Doppler Effect?


Took this picture last year at the celery fields in Sarasota, Florida. Upon inspection of this picture only, I could tell which direction the moon is moving.

The beauty and power of science (physics in this case) never cease to amaze me.

Please contribute to this thread and make a guess about its heading and direction of motion.

Cheers
and Good Luck
Saba





Can you tell from this picture in which direction the moon is heading?



Edited on Feb 09, 2013 at 09:42 PM · View previous versions



Feb 08, 2013 at 12:42 AM
lanon
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p.1 #2 · p.1 #2 · Moon's Heading. The Doppler Effect?


I am not sure about the direction, but could you tell me what size lens you used to take this photo, or was it telescope mounted? Great detail


Feb 08, 2013 at 01:39 AM
CosmicCruiser
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p.1 #3 · p.1 #3 · Moon's Heading. The Doppler Effect?


the moon's heading east at one diameter per hour.



Feb 08, 2013 at 01:56 AM
OldProf
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p.1 #4 · p.1 #4 · Moon's Heading. The Doppler Effect?


lanon wrote:
I am not sure about the direction, but could you tell me what size lens you used to take this photo, or was it telescope mounted? Great detail

I am not sure of the camera. Could be my D300 or D7000. The lens was a Nikkor 400mm f/3.5 manual focus together with a Nikkor 301 2x teleconverter. It was mounted in my biggest Manfrotto tripod using a Kirk Enterprises ball head. It was about 6 minutes after moon rise.

Thanks for looking




Feb 08, 2013 at 03:34 AM
OldProf
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p.1 #5 · p.1 #5 · Moon's Heading. The Doppler Effect?


CosmicCruiser wrote:
the moon's heading east at one diameter per hour.



Hello Robert,
You are, are of course absolutely correct! However, in this particular picture it is not moving 90 degrees to the right.

Thanks for your interest and looking.
Cheers
Saba



Feb 08, 2013 at 03:40 AM
Greg Campbell
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p.1 #6 · p.1 #6 · Moon's Heading. The Doppler Effect?


Please define 'heading.'

Apparent motion in the sky?
Change in orbital distance?





Feb 08, 2013 at 06:00 AM
OldProf
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p.1 #7 · p.1 #7 · Moon's Heading. The Doppler Effect?


Hello Greg,
Sorry for being vague about "heading". I mean the angle in the picture at which the moon would be moving. For example 0 degrees would be straight ahead. 90 degrees would be to the right; 270 degrees to the left etc. I hope this clarifies things.

Thank you for your interest
Cheers
Saba



Feb 08, 2013 at 12:33 PM
Jim8EL
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p.1 #8 · p.1 #8 · Moon's Heading. The Doppler Effect?


OldProf wrote:
...I am not sure of the camera. Could be my D300 or D7000. The lens was a Nikkor 400mm f/3.5 manual focus together with a Nikkor 301 2x teleconverter. It was mounted in my biggest Manfrotto tripod using a Kirk Enterprises ball head. It was about 6 minutes after moon rise.

Thanks for looking


D7000...it's in the EXIF.



Feb 08, 2013 at 01:06 PM
Greg Campbell
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p.1 #9 · p.1 #9 · Moon's Heading. The Doppler Effect?


It will be moving to the upper right, headed toward the '1' on a 12 hour clock.

Why do you ask?



Feb 08, 2013 at 02:31 PM
OldProf
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p.1 #10 · p.1 #10 · Moon's Heading. The Doppler Effect?


Thanks for the tip Jim.

Love your wildlife pictures and landscapes (including the cafeine and octane ones). The family name seems familiar too. Sort of like "Mattar".
Cheers
Saba



Feb 08, 2013 at 03:01 PM
 

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Jim8EL
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p.1 #11 · p.1 #11 · Moon's Heading. The Doppler Effect?


Thank you Saba. Nice shot.
Jim



Feb 08, 2013 at 03:32 PM
OldProf
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p.1 #12 · p.1 #12 · Moon's Heading. The Doppler Effect?


Greg Campbell wrote:
It will be moving to the upper right, headed toward the '1' on a 12 hour clock.

Why do you ask?

Thanks for the question Greg

The picture (and every other large one taken of the moon for that matter) illustrates the rare case of an optical doppler effect. The reflected sunlight's color, from the moon to the earth, is shifted according to how the moon is moving relative to us. It is in the order, from high to low frequencies: violet, indigo, blue, green, yellow, orange and red.

The subtle Doppler effect will be most visible at the circumference of the moon. Notice the blue color at the circumference in the upper right range between 9:30 to 12:00 to3:30 on the 12 hour clock. The maximum blue color is, as you correctly noted, at 1:30 and is the direction of motion of the moon! In the lower left range from 3:30 to 6:00 to 9:30 the circumference is yellow!

An even more subtle form of the Doppler effect becomes apparent if you magnify the circumference to the pixel level around 1:30. There you will see the blue to red layers stacked perpendicular to 1:30. Really fascinating.

Love your lanscapes and macro pictures. They are also accompanied by a unique sense of humor.
Take care and cheers
Saba

PS. This should not be misinterpred as a form of chromatic abberation.



Feb 08, 2013 at 03:43 PM
Older Fossil
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p.1 #13 · p.1 #13 · Moon's Heading. The Doppler Effect?


OldProf wrote:
Thanks for the question Greg

The picture (and every other large one taken of the moon for that matter) illustrates the rare case of an optical doppler effect. The reflected sunlight's color, from the moon to the earth, is shifted according to how the moon is moving relative to us. It is in the order, from high to low frequencies: violet, indigo, blue, green, yellow, orange and red.

The subtle Doppler effect will be most visible at the circumference of the moon. Notice the blue color at the circumference in the upper right range between 9:30 to 12:00 to3:30 on the
...Show more

Call me skeptical! I don't have the time right now to calculate the magnitude, but from my understanding of the physics, at the relative velocities involved, the wavelength shift should be miniscule and not detectable by our vision.

Also, the motion most people ascribe the moon is mostly apparent motion caused by the earth's rotation. The actual orbital motion of the moon is in the opposite direction from its apparent motion and is actually orbiting in the same direction as the earth's rotation. But the earth rotates much faster making the moon's apparent motion seem to go the opposite direction. This is why the moon rises about 53 minutes later each day.

I'll side with imperfect optics for this effect.

Art



Feb 08, 2013 at 05:30 PM
JimFox
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p.1 #14 · p.1 #14 · Moon's Heading. The Doppler Effect?


Hi Saba,

What a cool looking shot of the moon you got here. As to the direction it's heading, I would say it should be heading to the printer to get printed and put up on your wall...

Jim



Feb 08, 2013 at 06:24 PM
stanparker
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p.1 #15 · p.1 #15 · Moon's Heading. The Doppler Effect?


Some of you fellows are clearly brilliant, and I am so far behind you I haven't even learned to care which direction or how fast the moon travels. As long as someone else tells me the rise/set/phase, I'm good. Great shot of the moon.


Feb 08, 2013 at 06:36 PM
NCAndy
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p.1 #16 · p.1 #16 · Moon's Heading. The Doppler Effect?


Looks like CA to me, doppler or not. Great shot though.


Feb 08, 2013 at 06:49 PM
Jon Joshua
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p.1 #17 · p.1 #17 · Moon's Heading. The Doppler Effect?


Yeah. Looks like CA, but it wouldn't follow around the curvature of the moon at the top of the picture where there are darker spots.


Feb 08, 2013 at 08:47 PM
OldProf
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p.1 #18 · p.1 #18 · Moon's Heading. The Doppler Effect?


Older Fossil wrote:
Call me skeptical! I don't have the time right now to calculate the magnitude, but from my understanding of the physics, at the relative velocities involved, the wavelength shift should be miniscule and not detectable by our vision.

Also, the motion most people ascribe the moon is mostly apparent motion caused by the earth's rotation. The actual orbital motion of the moon is in the opposite direction from its apparent motion and is actually orbiting in the same direction as the earth's rotation. But the earth rotates much faster making the moon's apparent motion seem to go the opposite direction.
...Show more


Art, I think you are right about the magnitude of the shift. A simple back-of-the-envelope calculation, the earth would have to rotate 1000 times faster to cause a Doppler shift from blue to yellow. I will look into it further and try to get the true relative velocities (speed and direction).

That's the beauty of science and scientists. Every phenomenon can be challenged and scientists accept these challenges and rethink things until the phenomena or effect is fully understood.

Thank you for your comments. They are very helpful!
Saba



Feb 09, 2013 at 09:41 PM
Greg Campbell
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p.1 #19 · p.1 #19 · Moon's Heading. The Doppler Effect?


Visual Doppler? No, that's just not going to happen.

First off, as Fossil points out, the moon's velocity through space is entirely inadequate to produce a gross color shift. A sensitive spectrometer might see a very, very tiny wavelength/color shift, but to go from eg. blue to green would require MUCH more speed, on the order of 20% the speed of light. (See http://www.asterism.org/tutorials/tut29-1.htm )

Secondly, orbital velocity will not produce any significant spectral shift. Radial velocity (change in distance over time) is what you want. The moon's distance does vary during the course of it's orbit (by +/- 12,000 miles), but this occurs over many days, resulting in a rather low radial velocity that peaks somewhere in the low 1xx miles per hour range. The redshift this would produce would be completely, utterly, absolutely undetectable by the human eye.

One more point: Since the moon it gravitationally locked, with one side more or less facing the Earth at all times, you're not going to get much rotational velocity either.

Also consider that ALL the wavelengths emitted by the object are shifted. Depending on the direction of travel, ultraviolet or infrared will be shifted into the visual spectrum. If the object is not strongly colored in the first place (the moon is a pretty dismal dark grey with few emission peaks), there may be little apparent change.



Feb 10, 2013 at 05:55 AM
astro-ep
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p.1 #20 · p.1 #20 · Moon's Heading. The Doppler Effect?


Greg Campbell wrote:
Visual Doppler? No, that's just not going to happen.




Sure. Take a look at a car at night. When it's traveling away from you, it's red-shifted.





Feb 10, 2013 at 03:54 PM
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