[meteorite-list] The 2009 Orionid Meteor Shower

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon, 19 Oct 2009 15:36:56 -0700 (PDT)
Message-ID: <200910192236.n9JMau7Z012452_at_zagami.jpl.nasa.gov>

http://science.nasa.gov/headlines/y2009/19oct_orionids.htm

The 2009 Orionid Meteor Shower
NASA Science Nwes
10.19.2009

October 19, 2009: The Orionid meteor shower peaks this week and it
could be a very good show.

"Earth is passing through a stream of debris from Halley's Comet, the
source of the Orionids," says Bill Cooke of NASA's Meteoroid Environment
Office. "Flakes of comet dust hitting the atmosphere should give us
dozens of meteors per hour."

The best time to look is
before sunrise on Wednesday, Oct. 21st. That's when Earth encounters the
densest part of Halley's debris stream. Observing is easy: Wake up a few
hours before dawn, brew some hot chocolate, go outside and look up. No
telescope is required to see Orionids shooting across the sky.

Orionids appear every year around this time when Earth orbits through an
area of space littered with debris from the ancient comet. Normally, the
shower produces 10 to 20 meteors per hour, a modest display. The past
few years, however, have been much better than usual.

"Since 2006, the Orionids have been one of the best showers of the year,
with counts of 60 or more meteors per hour," says Cooke.

According to Japanese meteor scientists Mikiya Sato and Jun-ichi
Watanabe, 2006 marked Earth's first encounter with some very old debris.
"We have found that the [elevated activity of 2006] was caused by dust
trails ejected from 1P/Halley in 1266 BC, 1198 BC, and 911 BC," they
wrote in the August 2007 edition of /Publications of the Astronomical
Society of Japan/. In their paper "Origin of the 2006 Orionid Outburst,"
Sato and Watanabe used a computer to model the structure and evolution
of Halley's many debris streams stretching back in time as far as 3400
years. The debris that hit Earth in 2006 was among the oldest they
studied and was rich in large fireball-producing meteoroids.

Repeat encounters produced good displays in 2007 and 2008???and "the
meteoroids are expected to approach Earth [again] in 2009," say Sato and
Watanabe. They note that these old broad streams tend to produce equally
broad showers, lasting several nights around the peak. So, if clouds
interfere on the 21st, try again on the 22nd or 23rd.

The phase of the Moon favors a good show. The Moon is almost new and
completely absent from the pre-dawn sky at the time of the shower's
peak. Bright moonlight will not be a problem.

Last but not least, the display will be framed by some of the prettiest
stars and planets in the night sky. In addition to Orionids, you'll see
brilliant Venus, red Mars, the dog star Sirius, and bright winter
constellations such as Orion, Gemini and Taurus. Even if the shower is a
dud, the rest of the sky is dynamite.

Set your alarm and enjoy the show.

Author: Dr. Tony Phillips <mailto:james.a.phillips at earthlink.net> |
Credit: Science at NASA <http://science.nasa.gov>
Received on Mon 19 Oct 2009 06:36:56 PM PDT