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Waning gibbous moon


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Can anyone explain why on the 14 Oct 2022 at 7.00 UTC at location (Lat 52.339 Long 0.419)does the waning gibbous moon (Alt 39º) appear to be illuminated from a different direction, i.e. slightly upwards, than from the sun which is only at Alt 5º? The azimuth difference is 149.83º.

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It looks like that because of perspective... the moon looks to be illuminated from a different angle if the rays were falling on it from a "flat" perspective... but because of the distances and the sky is spherical, add to that refraction, the rays do not travel in a straight line from our perspective but in a curve... OK this is getting a bit hard to explain without sounding like a flat earther.

NOW I know that light travels in a straight line, but here we're talking from our perspective which looks curved.

See the image, the RA and DEC lines are straight lines, but due to the fact that they are straight around a spherical earth, this is how they are from our perspective, they appear curved, same goes with sunlight illuminating the moon...

see my crude illustration of the SUN & moon added to the skymap, simulating rays travelling on the 23h-11h line... the moon looks to be illuminated from a "wrong" angle... even though those lines are really straight but appear curved from our miniscule perspective. 

 

This was harder to put into words than when I visualised it....

Did that make sense?

 

 

RA DEC ILLUSTRATE.jpg

Edited by MarsG76
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