Orionid Meteor Shower, Leftovers from Halley's Comet, Set to Peak This Weekend

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Orionid Meteor Shower, Leftovers from Halley's Comet, Set to Peak This Weekend
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Astrophotographer Jason Hullinger took this long exposure of star trails and Orionid meteors Red Canyon State Park, CA near Mojave/California City on Oct. 21. 2012.

Editor's Note: The first photos and video of the 2013 Orionid meteor shower are in. See our latest story on the meteor display here: Orionid Meteor Shower Sparks Bright Fireballs (Video) 

Cosmic litter from Halley's Comet is set to pepper the night sky in a meteor shower before dawn this weekend and early next week.

The Orionid meteor shower can best be described as a lesser version of the famous Perseid meteor shower of August. The October shower is scheduled to reach its maximum before sunrise on Monday morning (Oct. 21). The meteors are known as "Orionids" because they seem to fan out from a region to the north of Orion's second brightest star, the ruddy hued Betelgeuse.

Currently, Orion appears ahead of Earth in the planet's journey around the sun. The constellation does not completely risen above the eastern horizon until after 11:30 p.m. local daylight time. [Photos: Orionid Meteor Shower of 2012]

At its best during the predawn hours around 5 a.m. EDT (0900 GMT) — Orion will be highest in the sky toward the south — the Orionids typically produce around 20 to 25 meteors per hour under a clear, dark sky. This shower is one of just a handful of known meteor showers that can be observed equally well from both the Northern and Southern Hemispheres.

Usually Orionid meteors are normally dim and not well seen from urban locations, so it's suggested that you find a safe, rural location to see the best Orionid activity.

Orionid activity tends to noticeably ramp-up by around Oct. 17 when they start appearing at roughly five per hour. The shower may be quite active for several days before or after its broad maximum, which may last from Oct. 19 through Oct. 23.  After peaking on the morning of Oct. 21, activity will begin to slowly descend, dropping back to around five per hour around Oct. 25.  The last stragglers usually appear sometime in early to mid November.

The moon 'muscles in'

Unfortunately, 2013 is a poor year for the Orionids thanks to the moon, which turns full on Oct. 18.  

On the morning of the Orionid maximum on Monday the meteor shower will share the sky with the brilliant light of a 94 percent illuminated gibbous moon. Although the Orionids will be at their peak, most of meteors will likely be obliterated by the bright moonlight.

If the moon, weather or poor timing obstructs your view of the meteor shower, you can also catch sight of the Orionids online. The online Slooh Space Camera will host live views of the meteor shower from the Canary Islands off the coast of West Africa on Oct. 20. The broadcast begins at 8 p.m. EDT (0000 Oct. 21 GMT) and you can watch the Orionid webcast on SPACE.com courtesy of Slooh.

Still, an exceptionally bright Orionid, darting from out of Orion's region might still be glimpsed. 

"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 this family tend to leave long-lasting trains."

Indeed, recent studies have shown that about half of all spotted Orionids leave trails that lasted longer than other meteors of equivalent brightness. 

Halley's legacy

The Orionids are the legacy of the famous Halley's Comet.

Comets are leftover pieces that date back to the formation of the solar system. The "dirty snowballs" are the odd bits and pieces of simple gases — methane, ammonia, carbon dioxide and water vapor — that went unused when the sun and its attendant planets came into their present form. 

Meteoroids released into space out of cometary debris are the remnants of a comet's nucleus. All comets eventually disintegrate into meteor swarms and Halley's is well into that process at this time.

Tiny particles — mostly ranging in size from dust to sand grains — remain along the original comet's orbit, creating a "river of rubble" in space. [See Photos of Halley's Comet Through History]

In the case of Halley's comet (which has likely circled the sun many hundreds, if not thousands of times), its dirty trail of debris has been distributed more or less uniformly all along its entire orbit. When these tiny bits of comet collide with Earth, friction with our atmosphere raises them to white heat and produces the effect popularly referred to as "shooting stars."

The orbit of Halley's Comet closely approaches the Earth's orbit at two places. Therefore, the debris creates two meteor showers: the Orionids in October and the Eta Aquarids in May.

Step outside before sunrise this weekend or early next week, 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.

Editor's note: If you snap an amazing picture of the Orionid meteor shower or any other night sky view that you'd like to share for a possible story or image gallery, send photos, comments and your name and location to managing editor Tariq Malik at spacephotos@space.com.

Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmer's Almanac and other publications, and he is also an on-camera meteorologist for News 12 Westchester, N.Y. Follow us @Spacedotcom, Facebook and Google+. Original article on SPACE.com.

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