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Astronomy/Astronomy, specifically Earth to Sun relationships

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Question
I understand that if the Earth were to cease revolution around the Sun, it would then be pulled into the Sun as a result of the Sun's gravity. How long would it take (approximately) for the Earth to get close enough to the Sun through this process so that life on Earth would be severely compromised? Also, is there anything that (to your knowledge) could cause the Earth to no longer revolve around the Sun, and if so what? Thank you for your time.

Answer
The only thing that could stop our revolution would be a catastrophic collision with an object comparable in size to the Earth, which would immediately pulverize and melt the Earth and its surface ephemera, so for all practical purposes the answer is nothing can stop the revolution that wouldn't make the rest of your question irrelevant.

However, if we could magically stop the revolution without any other untoward event, the Earth would fall from its present position to the Sun's surface in just over 2 months. This is based on Kepler's Third Law, P-squared = a-cubed. a, the size of our orbit, would be cut in half (one end being where we are and the other end being at the Sun, which is only half the size of our current orbit), so a-cubed would be 1/8 as big as now. That would make P a little over 1/3 of a year. But that would be the time required to go from "here" to the Sun and back to "here" (once all the way around the new orbit), and of course once we reached the Sun, that would be the end of things, so the time required to reach the Sun would be only half of that, or just over 1/6 of a year.

However, we would find it uncomfortably warm well before we reached the orbit of Venus, and although the rate of fall would be slow at first, I'm sure (even without doing any calculations) that it wouldn't take more than two or three weeks to severely compromise life in most parts of the Earth, and no more than a month to kill it off everywhere.

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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, and an online catalog of NGC/IC objects.

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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