Craig Lewis, age 14, of Broomall, Pennsylvania, for his question:

Why do bigger planets have banded atmospheres?

Patchy blotches come and go in the golden haze around Venus and also in the thin atmosphere of Mars. The giant planets beyond Mars also display changeable cloudy features. But their light and dark areas are designed in definite systems of bands parallel with their equators.

You need a telescope to view the banded atmospheres that surround the giant planets of our Solar System. The patterns are astonishing to behold, their rainbow tints are breathtaking. What's more, though the general pattern of light and dark bands prevails, it is forever changing. Jupiter's band system is more spectacular because it is the giant of the Solar System and also closer to us than Saturn. Uranus is smaller and farther away but powerful telescopes reveal that it too has a banded atmosphere. Neptune, almost twice the distance of Uranus, also appears to have a system of dim, dark bands.

In each case, the bands parallel the planet's equator, circling the tropical and tem¬perate latitudes at right angles to the axis of rotation. The polar regions are murky and somewhat blotbhed. Jupiter's equatorial region is banded with 14 alternating dark belts and bright zones. The entire system whirls and swirls with the rotating planets, the belt waver and divide, light and dark blotches appear and disappear. The changeable colors range from pearly grays and dusty browns through delicate greens and violets, pale pinks and rosy reds.

These similar planetary cloud patterns must be caused by similar planetary forces. We might guess what these forces are from a knowledge of our own earth. Suppose the wind and weather belts of our atmosphere were each tinged with color. A view from outer space would reveal the wide, warm trade wind belts moving in an easterly direction around the equator and the westerly belts of our temperate zones. These global winds are deflected east and west by the earth's rotation. If colored, they would resemble the bands around the big planets. The cold, dense atmospheres of the giants also are governed by the same forces of rotation and solar heat.

The big planets spin much faster than the earth and their dense atmospheric gases are hydrogen and helium, ammonia and methane. The intense cold and immense gravitational pressure adds electrical and other odd properties to these gases. Some reflect colors of the spectrum. Weather conflicts in the dense, cold atmospheres cause breezes that compare with earth type blizzards and their charged clouds generate electric storms beyond earthly imagination.

The prevalent bands are governed by the decreasing rotation speed between the equator and the poles. Jupiter's equator rotates in 9 hours and 54 minutes, while the temperate zones take five more minutes to complete each turn. The variegated colors may come from gaseous elements under extreme conditions, unknown on earth. The variable minor patterns are thought to be turbulent pockets in the lagging, overlapping wind belts and electric storms of Jovian dimensions triggered by gases under Jovian conditions of cold and pressure.