When the moon looks bigger when it's near the horizon ...
Discussion
I thought it was just an optical illusion due the mind being confused by the moon and horizon features normally being separate references and then being seen together, however ...
Wiki said:
Can anyone explain?Fallout said:
Thanks for that. 
mybrainhurts said:
mybrainhurts said:
Pretty sure that this is the explanation - optical illusions like this that rely on cognitive processing don't tend to be replicated by cameras.The orbit is slightly elliptical so there is a difference in apparent size caused by this - I think if I remember its about 10% maximum between the closest approach and the furthest. As thats a gradual process over the course of the orbit, I doubt you would be able to perceive it.
I've not watched the YouTube links but in short; viewing the moon at a low position in the sky involves the image being affected by the content of the atmosphere to a much greater extent.
The image is basically magnified by the water content present in our atmosphere because you are viewing it at an angle such that there is more of our atmosphere present for the light to transmit through.
HTH
The image is basically magnified by the water content present in our atmosphere because you are viewing it at an angle such that there is more of our atmosphere present for the light to transmit through.
HTH
Censorious said:
The image is basically magnified by the water content present in our atmosphere because you are viewing it at an angle such that there is more of our atmosphere present for the light to transmit through.
HTH
This is easily demonstrated as being a false explanation by examining a multiple exposure moonrise photograph.HTH
Measure the diameter of the moon at each exposure and you will see they are identical (in this case - about 50 pixels)
Moonhawk said:
Censorious said:
The image is basically magnified by the water content present in our atmosphere because you are viewing it at an angle such that there is more of our atmosphere present for the light to transmit through.
HTH
This is easily demonstrated as being a false explanation by examining a multiple exposure moonrise photograph.HTH
Measure the diameter of the moon at each exposure and you will see they are identical (in this case - about 50 pixels)
Are you saying that it always appears the same size but is merely an optical illusion with regard to perspective as suggested above by someone; is that the correct answer?
I wonder whether it is perhaps more generally explained by a higher atmospheric water/dust content irrespective of the position in the sky.
Censorious said:
Accepted but you have not given your definitive answer to this phenomenon.
Are you saying that it always appears the same size but is merely an optical illusion with regard to perspective as suggested above by someone; is that the correct answer?
I wonder whether it is perhaps more generally explained by a higher atmospheric water/dust content irrespective of the position in the sky.
It's an optical illusion (as explained in the video in post #2)Are you saying that it always appears the same size but is merely an optical illusion with regard to perspective as suggested above by someone; is that the correct answer?
I wonder whether it is perhaps more generally explained by a higher atmospheric water/dust content irrespective of the position in the sky.
If it were to do with atmospheric water/dust magnifying the image - the effect would be visible to a camera as well as our eyes.
Moonhawk said:
Censorious said:
Accepted but you have not given your definitive answer to this phenomenon.
Are you saying that it always appears the same size but is merely an optical illusion with regard to perspective as suggested above by someone; is that the correct answer?
I wonder whether it is perhaps more generally explained by a higher atmospheric water/dust content irrespective of the position in the sky.
It's an optical illusion (as explained in the video in post #2)Are you saying that it always appears the same size but is merely an optical illusion with regard to perspective as suggested above by someone; is that the correct answer?
I wonder whether it is perhaps more generally explained by a higher atmospheric water/dust content irrespective of the position in the sky.
If it were to do with atmospheric water/dust magnifying the image - the effect would be visible to a camera as well as our eyes.
So say Hangonamo, brother of Geronimo, but Geronimo not so sure...
Uhhm, interesting but...
How does this hypothesis explain that the moon can be viewed above the same landscape some nights from the same location and appear larger than on other occasions?
I still wonder whether atmospheric refraction plays a part; it can appear to be more common at certain times of year hence the term "harvest moon"
How does this hypothesis explain that the moon can be viewed above the same landscape some nights from the same location and appear larger than on other occasions?
I still wonder whether atmospheric refraction plays a part; it can appear to be more common at certain times of year hence the term "harvest moon"
Censorious said:
Uhhm, interesting but...
How does this hypothesis explain that the moon can be viewed above the same landscape some nights from the same location and appear larger than on other occasions?
You do have to factor in the fact that the moon is in an elliptical orbit - and so does actually appear larger (and brighter) in our skies depending on where it is in that orbit. The difference in the moons apparent size can be as much as 14-15% between apogee and perigee. Such occurrences are entirely predictable and there are online calculators that tell you when the closest approaches will occur. When a Perigee coincides with a full moon - that is when we get what is commonly referred to as a "super moon". This has nothing to do with atmospheric magnification though.How does this hypothesis explain that the moon can be viewed above the same landscape some nights from the same location and appear larger than on other occasions?
If the atmospheric effect were a real effect - there would be reams of data describing it, making specific predictions and scientific theories explaining how the effect arises (as there are for most other optical phenomena in our atmosphere).
Of course if you feel science has overlooked a legitimate phenomena - it would be easy for anyone on this thread to gather sufficient data to demonstrate it. All you need is a camera with a fixed focal length. Take images of the moon at different times of year and at different elevations - especially when you observe what you consider to be a moon that is larger than average. Examine the photographs and compare the size. Voila - proof. Then submit your analysis to one of the many peer reviewed scientific publications for consideration. Thats the great thing about science - pretty much anyone can do it.
Edited by Moonhawk on Wednesday 16th April 17:17
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