Leslie Dunn, ago 11, of Tucson, Ariz., for the question:

Do comets go in one direction?

A comet travels in mz orbit around the sun, Its orbit is a long narrow oval with a U turn at each end. Through part of its journey, it travels towards the sun then it males a sharp curve and travels away from the sun. It continues in this direction maybe to the outer limits of the Solar System. There it turns again and starts back in the opposite direction towards the sun again. The outer U turn of the comet's orbit is called its aphelion   meaning away from the sun. The U turn around the sun is called the perihelion   meaning all around the sun.

Through most of its orbit, a comet i s no more than a loose bundle of stones and debris. It bursts into glory only when it nears the sun, Then the comet glows with golden light and a huge, hazy halo spreads all around it. This is the head of the comet. The tail of the comet streams out from its golden head. It begins narrow end fans out wide towards the end. The tail of a real. razzle dazzle comet may be 150 million miles long and ten million miles at its widest. The word comet comes from an older word for hair because its trailing tail is like a golden pony tail

The amazing thing about the comet's pony tail is that it always .points away from the sun. As the razzle dazzle visitor curves around the sun, its tail whips around much faster. The comet acts like a duchess at court, who must always face the king and keep her train behind her. When the trip around the perihelion is finished, the comet recedes with its tail streaming out ahead of it.

Several hundred comets axe known to circle the sun and many of their orbits have been charted. The job is not an easy     one, for some of them visit the sun only once in centuries. They remain in view only for a few weeks as they make the U turn around the sun.  In this short time, the astronomers must gather enough facts to chart the rest of a comet's orbit.

The path of Halley's court, perhaps the most famous of all comets, is well charted. This dazzling showoff visits the sun once every 77 years and has been recorded since 240 B.C. The last appearance was in 1910 when its trailing glory was bright enough to be seen at high noon, Like all comets it speeded up as it approached and circled the sun aril slowed down as it chugged out into the cold void towards its aphelion.

In five years, this receding comet had passed the orbit of Saturn. By 1920, it was past the orbit of Uranus and in 1930, it passed the orbit of Neptune. It has taken more than 30 years to make the U turn around its aphelion and it will not re-cross the orbit of Neptune on its way back to the sun until 1965.