Halley's Comet or Comet Halley (officially designated 1P/Halley) is the best-known of the short-period comets, and is visible from Earth every 75 to 76 years. Halley is the only short-period comet that is clearly visible to the naked eye from Earth, and thus the only naked-eye comet that might appear twice in a human lifetime. Other naked-eye comets may be brighter and more spectacular, but will appear only once in thousands of years. Halley's returns to the inner Solar System have been observed by astronomers since at least 240 BC, and recorded by Chinese, Babylonian, and medieval European chroniclers, but were not recognized as reappearances of the same object. The comet's periodicity was first determined in 1705 by English astronomer Edmond Halley, after whom it is now named. Halley's Comet last appeared in the inner Solar System in 1986 and will next appear in mid-2061.
During its 1986 apparition, Halley's Comet became the first to be observed in detail by spacecraft, providing the first observational data on the structure of a comet nucleus and the mechanism of coma and tail formation. These observations supported a number of longstanding hypotheses about comet construction, particularly Fred Whipple's "dirty snowball" model, which correctly surmised that Halley would be composed of a mixture of volatile ices—such as water, carbon dioxide and ammonia—and dust. However, the missions also provided data which substantially reformed and reconfigured these ideas; for instance it is now understood that Halley's surface is largely composed of dusty, non-volatile materials, and that only a small portion of it is icy.

The meteor shower is predicted to peak early Thursday morning. Under ideal conditions (a dark, moonless sky) about 40 of these very swift meteors can be seen per hour.

The shower traditionally appears at about one-quarter peak strength for about three or four days before and after May 6.

The famous Halley's Comet takes roughly 76 years to circle the sun and last passed through our cosmic neighborhood in 1986. Halley's orbit closely approaches Earth's orbit in two spots, offering two chances each year to see meteor showers left over from the comet's cosmic "litter."

One point is in the middle to latter part of October, producing a meteor display known as the Orionids. The other point comes in the early part of May, producing the Eta Aquarids.

When and where to watch
There are, however, two drawbacks if you plan to watch for the Eta Aquarids meteors this year. [Meteor shower map.]

First, there is the moon, which is at last quarter on the peak morning and "muscles in" on the fainter meteor streaks by brightening the early morning sky with its bright light.



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