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Astronomy/View of Earth from Moon

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Expert: - 4/25/2011


Question
I enjoy doing little brain exercises, but I cannot find enough info on the web to satisfy my curiosity.  My question is this: If someone were observing Earth from the side of the Moon facing us, would they be able to map or observe the whole Earth or are they limited to seeing only a portion limited by the orbital path of the Moon? Thank you.

Answer
To a first approximation, the Moon moves north and south during one orbital period (27.3 days) the same way the Sun does during one year. On any given day, the Moon might not be visible from some part of the Earth (just as the Sun isn't, during some seasons), and someone on the Moon would be unable to see that part of the Earth. But over the course of 27.3 days, every part of the Earth would see the Moon at some time, and all of the Earth would be visible from the Moon.

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Volunteer

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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