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 any 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.

Your first chance to see Comet Hartley 2 itself in a dark sky will probably be in late October. In late October and early November, Comet Hartley 2 will pass in front of the feet of the constellation Gemini, to the right of Gemini's brightest stars, Castor and Pollux. But you'll have to stay up late to catch the comet as it rises above your eastern horizon but in that limited time frame before moonrise. You'll have more moon-free viewing time in early November, but keep in mind that the already faint comet will probably be dimming by the day, as it leaves the inner solar system.

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!

What does the comet look like?

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!

Deep Impact spacecraft also headed to Comet Hartley 2. By the way, the Deep Impact spacecraft – which was launched by NASA in 2005 and successfully sent a collider into Comet 9P/Tempel – had its orbit around the sun tweaked in May of 2010 with the goal of sending it close to Comet Hartley 2. This mission has now been re-designated EPOXI. The craft will pass most closely to the comet in early November, 2010. Mission overseers are provided status updates for EPOXI's impending sweep past Hartley 2.

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!

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Moonlight Meteor Shower Spawned By Halley's Comet - msnbc.com

Posted: 20 Oct 2010 07:20 AM PDT

A junior version of the famous Perseid meteor shower thought to have originated from the remains of Halley's Comet will hit its peak over the next week, but the light of the moon may intrude on the sky show.

This upcoming meteor display is known as the Orionids because the meteors seem to fan out from a region to the north of the Orion constellation's second brightest star, ruddy Betelgeuse.

The annual event peaks before sunrise on Thursday (Oct. 21) but several viewing opportunities arise before then for skywatchers in North America. [ Where to look to see the Orionids ]

The shooting stars are created by small bits of space dust — most no larger than sand grains — thought to be left over from the famed Halley's Comet, which orbits the sun once every 76 years.

Currently, Orion appears ahead of us in our journey around the sun, and has not completely risen above the eastern horizon until after 11 p.m. local daylight time.

The constellation is at its best several hours later. At around 5 a.m. – Orion will be highest in the sky toward the south – Orionids typically produce around 20 to 30 meteors per hour under a clear, dark sky.

But skywatchers beware: You will be facing a major obstacle in your attempt to observe this year's Orionid performance. As bad luck would have it, the moon will turn full on Oct. 23. Bright moonlight outshines fainter meteors, seriously reducing the number anyone can see.

The gradual build up to the full moon will hamper – if not outright prevent – dark-sky observing during the Orionid meteor shower's peak on Oct. 21.

The Orionids are actually already underway, having been active only in a very weak and scattered form since about Oct. 2. But a noticeable upswing in activity is expected to begin around Oct. 17, leading up to their peak night.

"Orionid meteors are normally dim and not well seen from urban locations," notes meteor expert, Robert Lunsford, adding that "it is highly suggested that you find a safe rural location to see the best Orionid activity."

Damage control for 2010

With all this as a background, perhaps the best times to look this year will be during the predawn hours several mornings before the night of full moon. That's when the constellation Orion (from where the meteors get their name) will stand high in the northeast sky.

In fact, three "windows" of dark skies will be available between moonset and the first light of dawn on the mornings of Oct. 18, 19 and 20.

Generally speaking, there will be about 150 minutes of completely dark skies available on the morning of the 18th.This shrinks to about 100 minutes on the 19th, and to about 50 minutes by the morning of the 20th.

This skywatching table shows prime Orionid meteor shower viewing times for some select U.S. cities.

In the table, all times are a.m. and are local daylight times. "Dawn" is the time when morning (astronomical) twilight begins. A "Window" is the number of minutes between the time of moonset and the start of twilight.

For example: When will the sky be dark and moonless for Orionid viewing on the morning of Oct. 20 from Houston?

Answer: There will be a 50-minute period of dark skies beginning at moonset (5:16 a.m.) and continuing until dawn breaks (6:06 a.m.).

Perhaps up to a dozen forerunners of the main Orionid display might appear to steak by within an hour's watch on these mornings, particularly on the 20th, the morning before the peak. It might even be worthwhile to try on Thursday morning, Oct. 21, although for most places, the moon will not set until just after the first light of dawn.

Halley's legacy

In studying the orbits of many meteor swarms, astronomers have found that they correspond closely to the orbits of known comets.

The Orionids are thought to result from the orbit of Halley's Comet, as some of the dust that has been shed by this famous object intersect earth's orbit around the sun during October.

There are actually two points along Halley's path, where it comes relatively near to our orbit. Another one of these points occurs in early May causing a meteor display from the constellation Aquarius, the Water Carrier.

The tiny particles that are responsible for the Orionid and Aquarid meteors are – like Halley itself – moving through space in a direction opposite to that the earth. This results in meteors that ram through our atmosphere very swiftly at 41 miles (66 km) per second. Of all the meteor displays, only the November Leonids move faster.

Orionid postmortem

After the peak, activity will begin to slowly descend, although most of the meteors will be squelched by the light of the moon. Rates drop back to around five per hour around Oct. 26. The last stragglers usually appear sometime around Nov. 7.

It is indeed unfortunate that the Moon will likely obliterate most of the Orionids in the nights following the peak, but the viewing odds will be much better before the break of dawn on those mornings leading up to the peak. Almost certainly, you should sight at least a few of these offspring of Halley's Comet as they streak across the sky.

In the absence of moonlight a single observer might see at least a couple of dozen meteors per hour on the morning of the peak, a number that sadly can not be hoped to be approached in 2010. In fact, it appears that this year, fans of the Orionids will be uttering the same lament that the old Dodger fans in Brooklyn used to: "Wait till next year!"

Lackluster Meteor Shower Sets Stage for Big Show in 2011 - msnbc.com

Posted: 10 Oct 2010 09:20 AM PDT

The Earth will pass through the cast-off remnants of an ancient comet Friday (Oct. 8), but the resulting meteor shower will be lackluster at best, experts say. Yet the event sets the stage for a truly remarkable shooting star display in 2011.

The source of this annual October meteor display, called the Draconid meteor shower, is dust and debris leftover from Comet Giacobini-Zinner.

The Draconid meteor shower has a reputation for disappointing skywatchers with lackluster displays, unlike the spectacular sky shows that sometimes accompany the annual Perseid meteor shower in August and the Leonid shower in November. [ Best Leonid Meteor Shower Photos ]

This year, according to skwatching experts, will be no different. But by all accounts, 2011 will be a year to remember for the Draconids.

"This year, forecasters expect Earth to narrowly miss several of the debris streams, resulting in no appreciable display for 2010," reported Spaceweather.com, a website dedicated to monitoring space weather and sky events. "Next year, however, could be different. On Oct. 8, 2011, Earth will have a near head-on collision with a tendril of dust, setting off a strong outburst of as many as 750 meteors per hour."

In fact, the 2011 Draconid meteor shower is expected to be so astounding that NASA has already begun preparing for the risk to satellites orbiting Earth such as the International Space Station or Hubble Space Telescope.

"We're already working with NASA programs to deal with spacecraft risk," said William Cooke, a scientist with the Meteoroid Environment Office at NASA's Marshall Space Flight Center in Huntsville, Ala., during an interview with SPACE.com in June. "I imagine when the word gets out there will be a Draconid outburst, I'll get the usual calls from Comsat companies as well as government space programs."

In addition to the chance of dings, there is the possibility of electrostatic discharges associated with the collision between a meteoroid and a satellite, Cooke said. Such discharges can account for a significant fraction of spacecraft anomalies during meteor showers, he added.

While this year's Draconid meteor shower will likely be a bust, the 2011 Draconids should be a sight to behold, forecasters said.

The best vantage points will be Europe, Africa and the Middle East, Spaceweather.com reported.

The 2011 Draconids could possibly be the most powerful meteor shower since the dazzling Leonids display 10 years ago, the website added.

Meteor

Tuesday, November 2, 2010

“Comet Hartley 2 to bring meteor shower on November 2 and 3? - Earth & Sky” plus 2 more

“Comet Hartley 2 to bring meteor shower on November 2 and 3? - Earth & Sky” plus 2 more

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