October 18, 2012
Everything You Need To Know About This Weekend’s Orionid Meteor Shower
[WATCH VIDEO: A Meteor Shower From Halley's Comet]
Lawrence LeBlond for redOrbit.com - Your Universe Online
Throughout the year Earth´s denizens are offered a number of good opportunities to witness meteor showers illuminating the night skies, with streaks of white lights racing across the upper atmosphere at lightning speed. Some of these seemingly heavenly showers, such as the late-April Lyrids, the Perseids of mid-August, and the often-spectacular Leonids, which arrive in November, are more notable than others.
This week, we are blessed with the presence of another notable meteor shower--the Orionids--which will peak this coming weekend, potentially putting on a dazzling show for sky watchers everywhere. In fact, the Orionids have already been dazzling some spectators, unleashing a rarely-seen fireball across the heavens that was visible for most northern Californians in the early evening hours last night (October 17).
Experts explained the huge fireball that caused many calls to the National Weather Service shortly after sightings was most likely a larger-than-average meteorite burning up as it entered the Earth´s upper atmosphere.
For the rest of us, we should have optimal viewing conditions in the predawn hours on both Saturday, Oct. 20, and Sunday, Oct. 21, with forecasters predicting early Sunday morning for prime viewing. Fortunately, a waxing crescent moon will set long before the prime time observing hours occur.
The Orionids, named for the point from which they appear to originate in the night sky, the constellation Orion, usually give spectators a fairly decent show of anywhere from 20-70 meteors per hour during its peak. From the Northern Hemisphere, observers should look for Orion, Sirius and Jupiter in the south before dawn. From the Southern Hemisphere, observers will need to look directly overhead.
The Orionids appear each year in mid-late October and, while they may appear to hail from the Orion constellation, they are actually the fallout from Halley´s Comet. Each year, when the Earth passes through a stream of dusty debris leftover from Halley´s Comet, earthlings are treated with a pre-dawn display of shooting stars for a period of several nights, with peak times occurring generally over a one or two night period.
“We expect to see about 25 meteors per hour when the shower peaks on Sunday morning, Oct 21st,” says Bill Cooke, the head of NASA's Meteoroid Environment Office. “With no Moon to spoil the show, observing conditions should be ideal.”
While the Orionids are not the strongest meteor shower of the year, they are “one of the most beautiful showers of the year,” notes Cooke.
However, its not the shower itself that is so beautiful, it´s the setting. With Orion, Taurus and Gemini in the backdrop, some of the brightest stars and planets can be observed while watching the Orionid bombardment. But this year, it´s even more spectacular. Venus and Jupiter have moved into position with Sirius to form a bright triangle in the eastern pre-dawn sky. And on the morning of Oct. 21, blazing meteorites will seemingly slice straight through the heart of this celestial triad.
Cooke suggests for optimal viewing, observers should head outdoors a few hours before sunrise (as early as 1 a.m. would do the trick) when the sky is dark and the constellation Orion is high overhead. It is best to find areas where the night sky is not lit up by city lights. For the best show, observers should lie down on a blanket, giving them a broad view of the heavens above. While the Orionids emerge from a small area near the star Betelgeuse (Orion´s shoulder), they will shoot out all across the night sky.
“Be prepared for speed,” he adds. “Meteoroids from Halley´s Comet strike Earth's atmosphere traveling 148,000 mph. Only the November Leonids are faster.”
Speed is important when it comes to meteorites. Fast meteorites tend to explode when they collide with the upper atmosphere, occasionally creating fireballs that leave incandescent streaks of debris in their wake that can linger in the sky for sometimes minutes. And often, these debris fields can twist themselves into complex shapes that are even prettier than the meteorites themselves.
“It really is a wonderful morning to be awake,” says Cooke. “Just don't plan on going anywhere in a hurry.”