If the Earth stopped rotating...

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Astrodelugeologist</i>
<br />Would such a change in the Earth's rotation have any effect on smaller orbiting bodies like artificial satellites?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">As a first approximation, no. Rotation does not affect gravitational forces. However, in the details, there would be some small, non-gravitational effects. For example, the atmosphere would stop rotating too, so air drag would change.

I assume we are not talking about relativistic "frame-dragging", which is a really, really tiny effect. -|Tom|-

Tom,

Was wondering if angular momentum would be reduced from zero rotation even though earth would still revolve around sun. Would earth have a reduction in gravitational forces if it did not rotate? Obviously, life would not be able to survive on our planet if it lacked enough rotation to not have one side face the sun much like Mercury. This is my first post, I sure appreciate your forum. John

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by cosmicsurfer</i>
<br />Was wondering if angular momentum would be reduced from zero rotation even though earth would still revolve around sun.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">"Zero rotation" normally means zero angular momentum, which means non-rotating with respect to the stars, not the Sun.

By contrast, our Moon rotates once per month with respect to the stars, as it revolves around Earth once per month, so that it keeps the same face toward Earth.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Would earth have a reduction in gravitational forces if it did not rotate?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">No. Spin does not affect gravity. Perhaps you are thinking of centrifugal force? That would go away if Earth stopped spinning. It would mean that things on Earth's surface would weigh very slightly more, and Earth would lose its oblate shape.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Obviously, life would not be able to survive on our planet if it lacked enough rotation to not have one side face the sun much like Mercury.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Radar observations in the 1960s discovered that Mercury does <i>not</i> keep the same face toward the Sun as formerly thought. It spins three times every two revolutions.

If Earth kept the same face toward the Sun, its oceans would boil on one side and freeze on the other. But it could still have a habitable zone near the day-night boundary. -|Tom|-

Thanks, that was very clear....So, if earth had zero angular momentum gravity would become stronger because the outward push of rotational centrifugal forces would no longer counter balance the inward push of gravity, and the earth's oblateness around tropics would disappear. Sounds like spin provides an antigravity force at least around the equator. The moon then would be under slightly greater gravitational pressures from earth. Very interesting that Mercury does have rotation, I wonder if large masses exert enough pressure on their satellites to eventually degenerate orbital rotation to same face over time, and it would then follow that orbital masses gravity fields create friction between one another causing internal heating that generates both electromagnetic radiation and the slowing down of rotational orbits. The earth facing sun dilemma could sure be severe. I wonder if the heat engine of boiling oceans would create extreme wind conditions from heat rising and cold air rushing in, or would the corriolis effect be reduced to zero from no rotation and weather isolated to each side? I have heard the earth's rotation is slowing down, is the earth headed towards an eventual narrowing of life zones and extreme weather conditions? John

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by cosmicsurfer</i>
<br />I wonder if large masses exert enough pressure on their satellites to eventually degenerate orbital rotation to same face over time<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Yes, all major moons in the solar system keep the same face toward their parent planet. That is caused by tidal forces.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I wonder if the heat engine of boiling oceans would create extreme wind conditions from heat rising and cold air rushing in, or would the corriolis effect be reduced to zero from no rotation and weather isolated to each side?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">With no rotation relative to the Sun, Earth's atmosphere would approach a steady state condition without significant winds.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I have heard the earth's rotation is slowing down, is the earth headed towards an eventual narrowing of life zones and extreme weather conditions?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">No. Our Moon saves us. Billions of years in the future, Earth's rotation will slow until Earth keeps the same face toward the Moon. Then both the "day" and the "month" will be about two of our present months long. So temperatures will have extreme swings, as they do now on Mercury. We'd have a month of baking followed by a month of freezing. The only places without temperature extremes would be near the poles. -|Tom|-