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Re: [Phys-L] Where is the sky?



Ah yes a commonly held misconception. The moon certainly looks bigger on
the horizon, but if you look at it through a tube, it looks the same size as
overhead. Actually, using simple geometric optics one would expect it to be
a hair smaller on the horizon because you are farther away, but your brain
makes it seem bigger because you compare it with nearby objects. As I was
writing this I noticed John M.'s post which points this out very nicely.
Your senses can deceive you. Everyone should read one of the books about
optical illusions where they point out these things. Actually everyone
should be aware that your senses and memories are very fallible, so we use
writing and measurement instead of just remembering observations.

John M. Clement
Houston, TX


But the rising and setting moon does not have a larger angular size.

Alex. F. Burr


In a message dated 8/23/2013 1:14:34 P.M. Mountain Daylight
Time, bnettles@uu.edu writes:

I haven't done it, but I expect that the spectral
measurement of moonlight from a rising and setting moon will
be much "redder" than the overhead moon, but the larger
angular size causes the light to be coming through a more
diffuse path and so the redness isn't as pronounced

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