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Astronomy/Sun influence on Moon

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Expert: - 11/19/2010


Question
Dear expert,

Thank you for your answer about Sun's influence on Moon's geocentric velocity.

So since Sun's acceleration on Earth is equal to Sun's acceleration on Moon,
does this ensure that, if Sun's gravity were put off, Moon would be still 384,400km (in mean) away from Earth?
If it wouldn't, how long would be its new orbital radius?



                               Sincerely

Answer
That's correct. Whether the Sun exerted a force on the Moon or not, the Moon's basic orbit would be the same as now. The main difference (as I think I explained in my earlier note) is that the orientation of the Moon's orbit is gradually changing as a result of the Sun's gravitational effects. If the Sun didn't pull on the Moon, the changes in its orbital orientation would almost entirely disappear.

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Courtney Seligman

Expertise

I can answer almost any question about astronomy and related sciences, such as physics and geology. I will not answer questions about astrology and similar pseudo-scientific rubbish.

Experience

I have been a professor of astronomy for over 40 years, and am working on an online text/encyclopedia of astronomy.

Publications
Astronomical Journal, Publications of the Astronomical Society of the Pacific (too long ago to be really relevant, but you could search for Courtney Seligman on Google Scholar)

Education/Credentials
I received a BA in astronomy and physics and a MA in astronomy, both from UCLA. I was working on my doctoral dissertation when I started teaching, and discovered that I preferred teaching to research.

Awards and Honors
(too long ago to be relevant, but Phi Beta Kappa and Sigma Xi still keep trying to get me to become a paying member)

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