“Comet Hartley 2 to bring meteor shower on November 2 and 3? - Earth & Sky” plus 1 more |
| Comet Hartley 2 to bring meteor shower on November 2 and 3? - Earth & Sky Posted: 01 Nov 2010 08:03 AM PDT November 1st, 2010 - Astronomy Essentials Meteor experts at NASA have determined that – although it's a long shot – the evenings of November 2 and 3 might feature a meteor shower from Comet Hartley 2, the comet photographed and glimpsed by many with ordinary binoculars over this past month. These experts have jokingly dubbed this possible meteor shower the "Hartley-ids, " in the comet's honor. When any comet – such as Comet Hartley 2 – nears the sun, its ices loosen and the comet sheds a trail of debris. If the Earth passes through a cloud of comet dust left behind by Hartley 2, bits and pieces from the comet will burn up in Earth's upper atmosphere as "Hartley-id" meteors. The story of how this possible meteor shower came to be suggested by experts is fascinating, and you can read it here. We emphasize that a meteor shower from this comet might or might not materialize. As always with meteor shower, you'll have to wait and watch, preferably under a dark country sky. On November 2 and 3 – at nightfall and into the evening – sprawl out on a reclining lawn chair and look upward. If the meteors do materialize, they are likely to be slow-moving. Tracing the paths of the "Hartley-id" meteors backward, they will appear to come from the constellation Cygnus the Swan. Of course, you don't have to know where this constellation lies to be on the lookout for this possible meteor shower. If the shower materializes, the meteors will fly in various directions and in front of any number of constellations. Cygnus simply marks the radiant point, or point of origin, of these meteors.
Looking for a detailed sky chart showing Comet Hartley 2? Click here. Want to see planets, meteor showers, eclipses? Visit our night sky page – updated daily!
People have been reporting seeing Comet Hartley 2 in October 2010 skies – with binoculars – with some light pollution. A few claim to have spotted it with the unaided eye as the faintest of blurs, but only in areas of pristine darkness. This comet remains a challenge, even with binoculars. The image at right shows Comet Hartley 2 photographed on September 29, 2010. The photographer – Alan Murta – said he didn't manage to see it with binoculars from his (somewhat light-polluted) location on the outskirts of a city. This is just a long-exposure camera shot, he said – no telescope used. See the comet? It's in the middle of this photo: the fuzzy object just above and to the right of the star in the photo's center. That star is Lambda Cassiopeiae, by the way. Comet Hartley 2 has been reported as being large and diffuse, meaning its light is spread out over a wide area. The best conditions for seeing it are still to be found under a dark, country sky – free of city lights and moon. When searching for the comet, try using averted vision. That's the technique of looking to one side of the faint object you seek on the sky's dome, instead of directly at it. Comets are surprising objects in many ways. They are mysterious visitors – loosely bound balls of ices – from the outer solar system. Sometimes, comets appear without warning. Comet Hartley 2 has been expected for many years, however. Officially designated 103P/Hartley, it is a periodic comet, which returns again and again near our sun and Earth. Its orbital period is thought to be 6.46 years. Even so, the brightness and appearance of this comet – or any comet – never follows an ironclad forecast. Don't be surprised if Comet Hartley 2 exceeds or falls shy of expectation. You will need a dark sky – free of city lights or moonlight – to see this comet. Through your binoculars, it looks like a smudge of light against the dark sky background. Comet Hartley appears as a faint, fuzzy patch of light. The element of suspense always accompanies the return of a comet to Earth's sky. That's one reason they are fun to see!
All in all, it will be an interesting autumn season for comets, thanks to Comet Hartley 2. Be sure to make friends with the bright stars Castor and Pollux and its constellation Gemini, for the comet will be passing through this constellation in late October. The trick to comet hunting is to know right where to look and right when to look. Our next moon-free view of the comet will come in late October, and the comet should probably be visible with an optical aid from then through early November. Most people report the comet as being faint. It will be interesting to see how much longer we'll be able to view Comet Hartley 2, our transitory visitor to Earth's starry sky. And don't forget – find a dark, open sky and watch for the "Hartley-id" meteors on the evenings of November 2 and 3! This entry passed through the Full-Text RSS service — if this is your content and you're reading it on someone else's site, please read our FAQ page at fivefilters.org/content-only/faq.php This posting includes an audio/video/photo media file: Download Now |
| Comet Hartley 2 Could Deliver 'Bonus' Meteor Shower - msnbc.com Posted: 01 Nov 2010 01:47 PM PDT The icy Comet Hartley 2 put on an interesting show during an unusually close pass by Earth last month and is poised to be visited by a NASA space probe on Thursday (Nov. 4). Now, there may be an unexpected bonus: a new meteor shower. The new meteor shower, which astronomers have billed the Hartley-ids, could brighten the night skies in early November, with the peak times occurring between Nov. 1 and Nov. 3. [ Photos of Comet Hartley 2 ] In fact, some skywatching cameras have revealed two fireballs that may be the result of Hartley 2 meteors or maybe not. Here is the story: Recipe for a meteor shower As a comet nears the sun, particles are shed from its nucleus. Thus its orbit is not an imaginary path through space like Earth's, but a continuous trail of dust moving in the same direction as the comet. Every time Earth crosses one of these dust trails, it stops millions of orbiting particles, and alert observers might catch a glimpse of some of these plunging through our atmosphere from their location; air friction vaporizes the particle with a flash of light. This may start at about 80 miles (nearly 129 km) above the Earth and end a second or two later at about 40 miles (64 km). Strictly http://www.nydmv.state.ny.us/forms/mv232.pdf speaking, the word "meteor" is used only for this brief luminous lifetime. When still out in space, the particles are called meteoroids. A meteor that rivals Jupiter or Venus in brightness is a fireball. One that breaks up along its luminous flight across the sky often with a strobe-like flash is called a bolide. Some are so large that parts of them reach the ground and become geologic specimens called meteorites. In the case of Comet Hartley 2, the possibility of it spawning a meteor shower are practically nil: the orbits of the comet and Earth never intersect or approach each other close enough for that dusty comet material to interact with our atmosphere. But recently, something took place which made one meteor expert stop to reconsider the possibility. Fiery coincidence? On Oct. 16, a pair of NASA all-sky cameras caught an unusual fireball streaking across the night sky over Alabama and Georgia. It was bright, slow, and strangely similar to another fireball that passed over eastern Canada less than five hours earlier. The Canadian fireball was recorded by another set of all-sky cameras operated by the University of Western Ontario. Because the fireballs were recorded by multiple cameras, it was possible to triangulate their positions and determine their orbits. This led to Bill Cooke of NASA's Meteoroid Environment Office to make a remarkable conclusion: "The orbits of the two fireballs were very similar. It's as if they came from a common parent." As it turned out, the orbits of the two fireballs were not only similar to one another, but also roughly similar to the orbit of Comet Hartley 2. "It makes me wonder," Cooke said, adding that "thousands of meteoroids hit Earth's atmosphere every night. Some of them are bound to look like Hartley-ids just by pure chance." Comet crumbs from space So while the odds are still long for any kind of significant meteor activity from Comet Hartley 2, perhaps it is not entirely out of the question. In fact, 13 years ago I had discussed the possibility of a meteor shower from Hartley 2 on MeteorObs, an Internet forum for meteor observers. On Oct. 27, 1997, I posted a message which indicated that the orbit of the comet was probably too far removed from the Earths to create any meteors. The two orbits are currently separated by 6.2 million miles (10 million km). Like other comets, Hartley 2 leaves a dusty trail of material in its wake. This trail might widen to perhaps a million miles or more in width after it has circled the sun a few times, but in the case of Hartley 2, this still amounts to only a fraction of the present distance between the orbits of the earth and the comet. So at first glance it doesnt appear that any prospective meteor stream from comet Hartley 2 would be wide enough to even reach the vicinity of Earth. What if there IS a meteor shower? Lets play devils advocate for a moment and assume an observable meteor shower from Comet Hartley 2 is a lock. Because Hartley 2 is a member of Jupiter's comet family, it periodically passes close enough to that giant planet to have its orbit perturbed by Jupiter's gravitation. In fact, my own calculations show that over the past 40 years, Jupiter has notably altered the orbit of Hartley 2 at least three times: in Dec. 1993, Dec. 1982 and May 1971. And during the years 1985 and 1991, the distance separating the Earths orbit from the orbit of the comet was less than half what it is now. The dust that was shed by Hartley 2 during those years likely has orbited the sun three or four times and now just might be passing close enough to our orbit to perhapsencounter the Earth and produce meteors. As it turns out, Earth is rapidly approaching that part of its orbit where we will be passing closest to the orbit of Comet Hartley 2. We will, in fact, be nearest on the nights between Nov. 1 and Nov. 3. More interestingly, the source of any prospective meteors Comet Hartley 2 itself will have passed through this region of space just a week before Earth's own arrival. Since the greatest concentration of dusty material usually is in the general vicinity of a comet, the Nov. 1 to Nov. 3 timeframe offers skywatchers the best chance of catching a view of a Hartley-id meteor. Some observing tips If you want to see if there might be any meteor activity that can be traced back to Comet Hartley 2, here are a few tips: First, any meteors belonging to the comet will appear to emanate from out of the constellation of Cygnus, the Swan. At this time of year, Cygnus is almost directly overhead as darkness falls and does not set below the northwest horizon until around 3 a.m. local time. So, it will be in view for much of the night. In addition, during the key Nov. 1 to Nov. 3 interval, the moon will be a waning crescent and wont rise until after 3 a.m. local time. So it will offer no interference. Also, because Comet Hartley 2 and the Earth are traveling around the sun in the same direction, any Hartley-id meteor would appear to move very slowly across the sky. Their entry speed into our atmosphere would be equal to only 7 miles per second (11.3 kps); about as slow any meteor can be. Contrast this to the annual November Leonid meteor shower, whose particles are moving in a direction opposite to the Earth and hit our atmosphere head-on at 45 miles per second (72.4 kps). Leonid meteors usually flash across our line of sight in less than a second, but a Hartley-id meteor may take many seconds to pass across the sky. Such slow meteors often display hues of red or yellow orange in contrast to the white or blue-greens that the Leonids are known for. And lastly, keep your expectations low. Don't expect to step outside and immediately see meteors. Since the Earth may literally be right on the edge of the comet's dust trail, consider yourself fortunate if you see any Hartley-ids at all. In fact, Russian astronomer, Mikhail Maslov has made his own calculations for possible Hartley-id meteors in 2010. He concluded that "activity is not expected." NASAs Cooke is also skeptical. "It's probably going to be a non-event," Cooke said. But then again, as the old saying goes, "nothing ventured, nothing gained." "This sets up nicely," Cooke added. "Cool weather, waning moon, and the possibility of seeing a new shower. I will definitely be out observing if the weather cooperates." How about you? Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for The New York Times and other publications, and he is also an on-camera meteorologist for News 12 Westchester, New York. © 2010 Space.com. All rights reserved. More from Space.com. This entry passed through the Full-Text RSS service — if this is your content and you're reading it on someone else's site, please read our FAQ page at fivefilters.org/content-only/faq.php This posting includes an audio/video/photo media file: Download Now |
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