Posted on 07/22/2003 7:21:52 PM PDT by vannrox
Correct. The Earth's orbital period is a direct result of the distance and eccentricity of its orbit, not the rotation of the planet itself.
Actually do to a continuous (very slight) loss of mass from the Sun, the orbital period of the Earth is actually decreasing over time, not increasing. However, this is an extremely tiny amount. Even over 4.5 billion years the AU which is approximately 93 million miles (mean distance from the Earth to the Sun) has changed by about 28 thousand miles (~.0003%)
Note: different parts of the Sun rotate at different rates.
Not poppy-cock.
The reason the Moon keeps one face to the Earth (Its rotation on its axis matches the period of its orbit) is it is tidally locked to the Earth. This tidal locking will eventually cause the Earth and Moon to keep one face to each other.
Here is a more in depth explanation. The total angular momentum of the earth moon system, which is spin angular momentum plus the orbital angular momentum, is constant. (The Sun plays apart also) Friction of the oceans caused by the tides is causing the Earth to slow down a tiny bit each year. This is approximately two milliseconds per century causing the moon to recede by about 4 centimeters per year. As the Earth slows down, the Moon must recede to keep the total angular momentum a constant. In other words as the spin angular momentum of the earth decreases, the lunar orbital angular momentum must increase. Here is an interesting side note. The velocity of the moon will slow down as the orbit increases.
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