Halley’s comet won’t return to the inner solar system for another 50 years. But it makes its presence known the next few nights with a meteor shower. The shower isn’t named for the comet, though, but for the region of sky in which its meteors appear to “rain” into the atmosphere — the constellation Orion.
A meteor shower takes place when Earth flies through the orbital path of a comet, which is a big ball of frozen water and gases mixed with bits of rock and dirt. As the comet gets close to the Sun, some of the ices vaporize, releasing some of the solid particles. Over time, these bits of cometdust spread out along the comet’s path.
Halley has made a lot of trips around the Sun, so it’s shed a lot of debris, which has spread out all along its orbit. Earth flies through this path every October. As the particles of cometdust hit the atmosphere they vaporize, forming the incandescent streaks known as meteors.
The Orionids are pretty reliable, although not usually spectacular. At their peak, they produce a few dozen meteors per hour.
This year’s shower will be at its best on Friday night, although a few Orionids punctuate the sky for a few nights before and after the peak. The Moon will be a couple of days past last-quarter then, so it’ll rise in the wee hours of the morning. Its light will hamper the shower, but not overpower it — allowing us to see at least some of the “calling cards” of Halley’s comet.
Script by Damond Benningfield, Copyright 2011