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Segment: News Items
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Segment: Who's That Noisy
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Who's That Noisy
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Answer to last week - radio noise from Saturn
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Segment: Questions and E-mails
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Question #1 - Orbit of Phobos
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It was mentioned that Phobos is falling to Mars because it's orbiting faster than the planet's rotation and that the Earth's moon is spiraling out because it's orbital period is longer than a day.
Could you check on this? I'm not knowledgeable enough about the mathematics involved (we're talking about a three-body system since Phobos' orbit is influenced by Deimos) and it doesn't add up with what I've been taught about orbits.
It seems to me that orbital speed doesn't involve a planet's rotational speed at all. A stable orbit is dependent on altitude and the masses of the objects involved. As the orbit increases distance from the planet the slower the object needs to go to remain stable. In other words, the higher the orbit, the slower the orbital velocity.
Earth and Mars have very much the same periods (24 hours vs 24 hours, 40 minutes) and if your statement held true, they'd have very much the same geosynchronous orbit altitude. Yet a geosynchronous orbit over Earth is about twice that of Mars. Please see:
http://www.alcyone.com/max/writing/essays/geostationary-orbits.html
Vernon Balbert
Oregon
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Segment: Interview
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Segment: Science or Fiction [ Click Here to Show the Answers ]
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Segment: Quote of the Week
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Quote of the Week
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"Nothing is so fatal to the progress of the human mind as to suppose that our views of science are ultimate; that there are no mysteries in nature; that our triumphs are complete, and that there are no new worlds to conquer."
Sir Humphrey Davy
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