Friday, October 20, 2006

See debris from Halley's Comet this Saturday

Step out under the night sky on Saturday and you may spot some pieces of debris from the famous Halley's Comet. The Orionid meteor shower will peak on October 21. These meteors or "shooting stars" are from the dust particles left behind by Comet Halley in space. If you're observing under clear and extremely dark sky, you may spot at least 15-20 of these per meteors per hour. From Space.com:
The best time to watch begins from 1 or 2 a.m. local daylight time until around dawn, when the shower's radiant (in Orion's upraised club, just north of the bright red star, Betelegeuse) is highest above the horizon. The higher the radiant, the more meteors appear all over the sky. The Orionids are one of just a handful of known meteor showers that can be observed equally well from both the Northern and Southern Hemispheres.

The Orionids are one of the better annual displays, producing about 15 to 20 meteors per hour at their peak. Add the 5 to 10 sporadic meteors that always are plunging into our atmosphere and you get a maximum of about 20 to 30 meteors per hour for a dark sky location.

Most of these meteors are relatively faint, however, so any light pollution will cut the total way down.

The shower may be quite active for several days before or after its broad maximum, which may last from the 20th through the 24th. Step outside before sunrise on any of these mornings and if you catch sight of a meteor, there's about a 75 percent chance that it likely originated from the nucleus of Halley's comet.

A few Orionids may appear as early as Oct. 9 and as late as Nov. 7. In 1993 and again in 1998, maximum activity unexpectedly came early, on the night of Oct. 17-18. "The activity is not constant from year to year," notes Russian meteor expert, Dr. P.B. Babadzhanov. "The time of maximum shifts significantly and there are secondary maxima."

"They are easily identified . . . from their speed," write David Levy and Stephen Edberg in Observe: Meteors, an Astronomical League manual. "At 66 kilometers (41 miles) per second, they appear as fast streaks, faster by a hair than their sisters, the Eta Aquarids of May. And like the Eta Aquarids, the brightest of family tend to leave long-lasting trains. Fireballs are possible three days after maximum."
Here's how to locate the radiant of the shower. Too bad the haze in Singapore will most likely prevent us from seeing anything this year.

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