Guest Author - Lea Terry

If you missed the last appearance of Halley’s Comet in 1986, you may get a second chance this weekend--sort of. The Orionids meteor shower, believed to be the remnants of Halley’s Comet, peaks Sunday morning, Oct. 21.

Origins of the Orionids

The shower’s name comes from its origin in the Orion constellation. The meteors appear to emanate from an area north of Betelgeuse, Orion’s second brightest star. The Orionids are one of two showers left behind by Halley’s Comet; the Aquarids, which appears in May. The Orionids is one of the fastest moving meteor showers, at about 41 miles per second--this rate is second only to the Leonids meteor shower in November. The Orionids usually fall at about 20 to 25 per hour, however, last year they fell at between 40 and 50 per hour. A similar increase in activity was reported between 1933 and 1938 as well, suggesting that the shower may be unusually vibrant again this year. After its peak on Sunday morning, the rate will decrease, dropping to about 5 per hour around Oct. 26, and disappearing sometime between early and mid-November.

Observing the Orionids

The shower should peak sometime between 1 a.m. and sunrise Sunday, and will be most visible in areas with few street lights. City skywatchers will have more difficulty obtaining a clear view. The shower is easily visible without binoculars or a telescope, and for the best view, choose a spot with a wide view of the sky, and lie back (bring a blanket or lounge chair). The shower continues even after its peak on Sunday, so the following mornings may provide a worthwhile display as well.

History of the Orionids

The Orionid shower was first documented in 1839 by E. C. Herrick of Connecticut, and was confirmed by A. S. Herschel on October 18, 1864. After this, interest in the Orionids increased considerably, and soon it was one of the most watched annual meteor showers. 1892 brought the first estimates of the shower’s activity--15 per hour. With more observations, it was realized that the rate fluctuated from year to year.

During the early 20th century, there was disagreement about the shower’s radiant, or the point in the sky from which it seemed to radiate. British amateur astronomer W. F. Denning claimed the radiant moved from night to night. American astronomer C. P. Olivier said it did not. Eventually, photography and the careful observations of several astronomers, amateur and professional, proved Olivier’s argument right.