B Why does the moon appear tilted?

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The discussion centers on the phenomenon of the moon appearing tilted, challenging the common explanation that it is merely an optical illusion. The original poster argues that this explanation fails to account for the laws of light transmission, suggesting that light travels in straight lines, which complicates the idea of moon tilt. They draw an analogy with a football illuminated by a light source to illustrate their point, questioning why similar reasoning cannot apply to the moon and sun. The conversation also references various resources for further understanding, including links to explanations of the lunar terminator illusion. Ultimately, the discussion seeks to clarify the mechanics behind the moon's appearance and invites further documentation on the topic.
Jackamus
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TL;DR
Observing a waning gibbous moon at about 8.00am one morning it appeared that its direction of illumination, a downwards angle of about 45º, could not be coming from the sun as the sun was much lower in the sky.
Researching this I found that the usual explanation was that it was an 'illusion'. However this explanation, in my opinion, does not stand-up to the laws governing the transmission of light. I proposed that as light travels in a straight line this poses a problem for moon tilt.
Most of the explanations appealed to the curved lines on panoramic photos whilst others appealed to the great circle of an imaginary celestial sphere.
I used, as an example, a football illuminated by a bright light. It is easy to see the direction of the light from observing the illuminated part of the football and tracing back in a straight line to the light. Why cannot the same reasoning be applied to the moon and sun since it is only a matter of scale?
 
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What? Do you have any documentation of this phenomena or did you just observe with your eyes? And it sounds like you are saying that the moon isn't illuminated by the sun...? Huh?
 
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