Douglas Wilson, age 12, of Oxford, Nebraska, for his question:

What makes a comet's tail point away from the sun?

The word "comet" was coined from older words meaning "long hair." The showy visitors reminded ancient astronomers of long golden tresses trailing in the wind. Modern astronomers do not agree about the golden hair. But they do agree that the long streamers are blown by stiff cosmic breezes.

A comet's brief glory is borrowed from the sun. Out in space it is a cold, dark object traveling around an immense orbit. If is happens to be a comet that visits our skies, it begins to glow near the orbit of Jupiter. And glowing materials can be identified by spectra analysis. Astronomers know its major ingredients and they also know something of the stupendous outpouring of solar radiation. They can estimate what most likely happens to the comet as it sweeps in its U turn close around the sun. But at present, the experts are not certain of all the details of the tail's formation.

The factors involved are.the pushing force of solar radiation and its effect on the ingredients in the speeding comet. About 80 per cent of the big dirty snowball is a mixture of frozen water, methane and ammonia. Frozen in the icy mass are meteoric specks of iron and nickel, silicon and sodium, manganese, aluminum and calcium. Its total weight is one . tenth that of water. And this little lightweight is exposed to at least two stupendous forces pushing out from the sun. These forces and the comet's speed are stronger than the sun's mighty pulling power of gravity.

Instead of being pulled into the sun, fragments of the comet's materials are pushed away in a long, luminous tail that points away from the sun. As the comet nears the orbit of Jupiter, its outer crust of ices evaporates and forms a halo of glowing gases. This golden halo grows as the comet nears the sun. Light exerts pressure and the pressure of sunlight begins to push back a budding tail of glowing gas molecules. The sun also pours out a solar wind of energetic ions. After the comet crosses the orbit of Mars, the pressure of sun light and the blasting solar wind push back its tail to perhaps 60 million miles or more comet's tail.

Every moment, more material evaporates and joins the comet's trailing tail. Its gaseous molecules absorb ultraviolet rays from the sun and transform them into visible light. Other fragments add to the glowing glory merely by reflecting sunlight. Sunlight and solar wind push outward, always outward, forcing the comet's tail to point away from the sun. As the comet makes its fast U turn, the tail swings even faster. Every moment, fresh streams of fragments from the comet borrow the golden glory of the sun. When the U turn is completed, the comet speeds back into space. The pressures continue to push away from the sun. Now the glowing gases stream on ahead and the comet follows its golden tail.

There is still a lot to be learned about the nature of the comet's tail. Its gases are molecules of carbon with nitrogen and hydrogen combined with atoms of oxygen, carbon or nitrogen. These molecules are severed easily by sunlight and driven in glowing streamers away from the sun. The tail may be huge and bright enough to be seen at noon. But its gases are very thin. It is estimated that one glowing particle in the razzle dazzle tail might have to travel a million miles to meet its nearest neighbor. No wonder the sun's mighty pressures can drive back this filmy material with such determined force.