Sun- Moon anomaly

Got a beginners' question? No matter how elementary, our friendly forum community and magazine writers will answer it.

Re: Sun- Moon anomaly

Postby Graeme1858 » Sun Sep 16, 2018 6:17 pm

I just took the dog for a walk along the top of the Great Lines at Chatham. There's a good view of the horizon to the South and this evening a good view of the Sun and the Moon. At 17:20 they were both level in the sky but the Moon's terminator was indeed not vertical! I would say that the apparent anomaly is caused by the fact that the Sun has not yet set. They both look at the same height in the sky but the Sun is 400 times further away so they only look the same height from our perspective. The Moon is at first quarter phase today so the terminator is right through it's middle. I'm guessing that at sunset when the Sun is on the horizon and the Moon is due South, the perspective or parallax or whatever is causing the anomaly will sort it's self out and the terminator will be vertical.
Miranda 10x50 Binoculars
Celestron CGX 9.25" SCT
Posts: 223
Joined: Tue Jul 24, 2018 2:32 pm
Location: Kent, UK, 51°28’N 0°38’E


Return to Ask a silly (astronomy) question

Who is online

Users browsing this forum: No registered users and 0 guests