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ZetaTalk: Gaseous Planets
Note: written during the 2001 sci.astro debates.


Gaseous planets work on the same principles driving their rotation, but due to the lack of a solid crust their cores and atmospheres merge, where the rotation patterns on the surface of a planet with a solid crust is altered by the form and shape that crust takes. In rotation within a liquid or mobile core, the rotation rate differs for the various parts of the core. Rotation, as we have explained, is driven by parts of the core moving toward or away from elements outside of the planet. Like runners in a race, some parts move faster and others more slowly, depending upon the strength of the attraction or repulsion that is driving their motion within the core. There are also differences in mass, so that some parts of the core float closer to the surface, and others fall to the center of the core. What does all this do to the rotation of a gaseous planet, where the drama of rotation in the core expresses itself on the surface of the gaseous giant?

Just as the oceans of the Earth pool about her Equator, due to being slung there by the motion of rotation, just so the lighter elements in a gaseous planet pool about its equator, with the heavier elements lining up in bands toward the poles. Motion in a liquid or gaseous core, once started, is driven also by the very motion itself. Around the equator, the lighter elements rush to the surface, and there find they cannot leave due to the gravity pull of the planet, but also are being pushed from behind by more of the same element rushing to the surface. What happens in a fast flowing river, to the water along the banks which are being slung away from the pressure at the center? Eddy current occur, where the pull of the flow at the center creates a relative vacuum in that there is a difference in water pressure along the fast flow, so that water slung to the sides of the flow circle back into those spots of lesser water pressure. Likewise, eddy currents occur in a gaseous planet’s latitude bands, so that the motion of rotation apparent on the surface appears to be alternating bands with an east-west motion. The heaviest elements in such a planet pool at the core, and due to the motion of rotation which slings the lighter elements toward the surface of the planet, these heavy elements also creep up toward the poles. All else, the lighter elements, have left for the surface, and been pulled based on their relative weight toward the equator of the planet. The poles, thus, reflect the overall rotation direction of the gaseous planet.

On Earth, these same patterns exist, but due to the buffering action of the crust the atmosphere operates independently. Where the Earth moves under the atmosphere, the drag is from east to west, and as the atmosphere is not so inclined, eddy currents, the prevailing westerlies, are created. Storms on Earth, created due to unequal pressure of air masses and their relative humidity, last only as long as equalizing the factors takes - a matter of days. Storms on a gaseous planet, noted by NASA in July, 2001 from recent images taken by a fly-by probe, seem to last for long periods. This is because they are not driven simply by a thin and highly mobile air mass, but by elements disbursed in the entire core of the planet. Equalization is not in a thin layer, but as deep as the planet itself, so the drama takes longer to resolve.

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