Welcome to You Ask Andy

Ernie Henry. age 11. Phoenix. Arizona.

How long has Halley's comet been recorded?

Once or maybe twice in a lifetime. a glorious visitor comes to our skies. We call it a comet. a name coined from older words meaning a long‑haired star. A few little comets show up in telescopes every year. But when a big one arrives no lenses are needed to see it. Its head looks like a bight star. Its glowing tail may hoop over half the sky. At times it is bright enough to be seen at high noon. The golden haired visitors have impressed people since earliest times. They were noted in records for thousands of years.

Like a true showman. a comet performs on schedule. It may not return for hundreds or thousands of years. But it returns at regular intervals. This was hard to figure out for a long time. Halley's comet appears regularly every 75. years so we all have a chance of seeing it in a lifetime. Those alive at the time are not likely to have missed the 1910 showing. The next appearance is scheduled for 1986.

Halley's is the comet that helped to solve the riddle of other comets. Isaac Newton had just startled the world by explaining the laws of gravitation. Edmund Halley was Astronomer Royal of England. He saw hour these laws might control the paths of the cornets. He studied the old records of comets with Newton's information in mind. One comet he had seen for himself in 1682 at the age of 26.

There were records of a bright comet in 1531 and 1607. A big comet seemed to show up regularly every 75 years or so. Halley was sure it must be one and the same performer. the one he had seen in 1682. He predicted a return engagement for late 1759 or early 1760. Halley did not live to see his comet a second time. But the first glimpse of it was reported on Christmas Day. 1759 ‑ right on schedule.

Naturally. the heavenly body was named Halley's comet. More old records were searched. The long‑haired showoff had been recorded on 28 trips. each about 75 years apart. Its record goes back to 240 B. C. Only one visit went unrecorded in went unrecorded in all that time.

Like all comets. its head looks like a star. Around it is a deep. fuzzy halo. The head may be only a few thousand miles across. Distant stars may be seen right through the head of some comets. The center may well be only a loose collection of rocks and meteors. The fuzzy halo is most likely made of very thin gases.

The golden tail is certainly made of thin gages. In 1910. on May 17 and 18. the earth passed right through the tail of Halley’s comet. A few people noticed a faint glow in the sky. Nobody else noticed a thing: What it lacks in weight. the glowing tail makes up for in size. When on display. the tail of Halley’s comet is some 40 million miles long.

The comet shines from the reflected glory of the sun. Its orbit is long and narrow. One end loops close around the sun. The comet swings around this end of its orbit like a lady in waiting before her queen. The golden train always streams backwards and away from the sun.

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