wpostServer: http://css.washingtonpost.com/wpost2

Most Read: Local

Posted at 10:31 AM ET, 10/19/2012

Bits of Comet Halley: This year’s Orionid meteor shower peaks this weekend


In this photo, a shooting star above the Montebello Open Space Preserve in Palo Alto, Calif. Streaking fireballs lighting up California skies and stunning stargazers are part of a major meteor shower, and the show is just getting started, professional observers said. (Phil Terzian - AP)
Going deep into antiquity, ancient sky gazers saw the comet we now call Halley. In modernity, you can see Comet Halley’s bits and pieces this weekend as they light up the night October 20-21 when you behold the annual Orionid meteor shower’s peak.

While the Orionids may not be the most well-known group of shooting stars, you can amaze friends at this weekend’s parties if you learn a little bit about them.

Astronomers predict the Orionids will peak at 20 to 25 meteors per hour, or for astronomers, the zenithal hourly rate. To peek at the peak, start looking about 10 p.m. on Saturday night through the first vestiges of dawn on Sunday. If you are persistent at watching, you may see a handful each hour.

Orionid meteors are fast, bright and sometimes offer beautiful, persistent trains. They’ve been around since Oct. 2 and will likely last until Nov. 7, but like autumnal leaves peak in color, meteor showers peak in numbers. So every once in a while for several weeks, you’ll spot one in the heavens on the non-peak nights. (Ottewell, 2012 Astronomical Calendar.)

With this weekend’s Orionids peak, how do you find them? Dress very warmly. Pack a Thermos brand insulated container with strong coffee or hot chocolate. Go outside. And then look up. It’s that easy. They will be all over the night sky, but generally speaking they will appear to emanate from the Orion constellation, which rises in the east in the 10 p.m. hour.

Science@NASA presents a short YouTube video on viewing the 2012 Orionid meteor shower:

Meteor showers occur when Earth – on its annual trip around the sun – smacks into the debris trails of long ago comets. When earth passes through this cosmic trash, these tiny dots of dirt hit Earth’s atmosphere and burn, and they appear as meteors streaking through our night sky.

For the Orionid meteors, the parent is Comet Halley – arguably the world’s most famous. While comets are named for their discoverer, meteors are named for the night sky from which they appear to emanate. In this case, the meteors look like they came from the Constellation Orion – thus, the Orionids. (Next month, meteors will look like they came from the Constellation Leo, or the Leonids.)

Sometimes shooting stars surprise us and produce stronger showers than expected. Between 2006 and 2009, the Orionids produced between 40 to 70 meteors an hour at peak. Astronomers generally believe that 2012 won’t produce extra activity. (Ottewell.)

Of Fast and Fireballs

Be prepared for speed, says Bill Cooke, the head of NASA’s Meteoroid Environment Office. “Meteoroids from Halley’s Comet strike Earth’s atmosphere traveling 148,000 mph. Only the November Leonids are faster.”

Cooke explains that speed is important because fast meteors have a tendency to explode. Occasionally, he says, Orionid fireballs leave incandescent streams of debris in their wake that linger for minutes.

In 2006, two Czech astronomers reported “exceptional fireball activity” of the Orionids in 2006. Czech observatories (part of the European Fireball Network) recorded 48 fireballs belonging to the Orionids. Seven of the 48 were recorded within a two-hour span on Oct. 20-21, 2006.

Sources: Rebecca Johnson, StarDate Magazine, University of Texas, www.stardate.org ; Guy Ottewell, Astronomical Calendar 2012, www.universalworkshop.com; Observer’s Handbook 2012, The Royal Astronomical Society of Canada, www.rasc.ca ; “Exceptional Fireball Activity of Orionids in 2006,” by Pavel Spurny and Lukas Shrbeny, in the journal Earth, Moon, and Planets; NASA.

By Blaine Friedlander  |  10:31 AM ET, 10/19/2012

Categories:  Astronomy, Latest, Space

 
Read what others are saying
     

    © 2011 The Washington Post Company