Comets


Meteor

Billion Tonne Comet May Have Missed Earth By A Few Hundred Kilometres in 1883


Technology Review
Tue, 18 Oct 2011 14:53 UTC
Image
© UnknownSchwassmann-Wachmann 3 comet which broke apart as it re-entered the inner Solar System in 2006
A re-analysis of historical observations suggest Earth narrowly avoided an extinction event just over a hundred years ago

On 12th and 13th August 1883, an astronomer at a small observatory in Zacatecas in Mexico made an extraordinary observation. José Bonilla counted some 450 objects, each surrounded by a kind of mist, passing across the face of the Sun.

Bonilla published his account of this event in a French journal called L'Astronomie in 1886. Unable to account for the phenomenon, the editor of the journal suggested, rather incredulously, that it must have been caused by birds, insects or dust passing front of the Bonilla's telescope. (Since then, others have adopted Bonilla's observations as the first evidence of UFOs.)

Today, Hector Manterola at the National Autonomous University of Mexico in Mexico City, and a couple of pals, give a different interpretation. They think that Bonilla must have been seeing fragments of a comet that had recently broken up. This explains the 'misty' appearance of the pieces and why they were so close together.

But there's much more that Manterola and co have deduced. They point out that nobody else on the planet seems to have seen this comet passing in front of the Sun, even though the nearest observatories in those days were just a few hundred kilometres away.

Comment: Also, the reader may be interested in Was the "First Photographed UFO" a Comet? and Comet Biela and Mrs. O'Leary's Cow

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Meteor

Halley's Comet to Put on Meteor Show Next Week

Joe Rao
SPACE.com
Fri, 14 Oct 2011 20:13 UTC
If you step outside before dawn during the next week or so, you might try to catch a view of some "cosmic litter" that has been left behind in space by Halley's Comet: the Orionid meteor shower.

The Orionids can best be described as a junior version of the famous Perseid meteor shower. This year's Orionids show is scheduled to reach its maximum before sunrise on the morning of Oct. 22. The meteors are known as "Orionids" because the fireballs seem to fan out from a region to the north of Orion's second brightest star, ruddy Betelgeuse.

Image
© NASA courtesy of Meteor Physics Group, University of Western OntarioA 2010 Orionid meteor, seen over Western Ontario, Canada. A waxing gibbous moon shines brightly at the left side of the image.
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Blackbox

Was the "First Photographed UFO" a Comet?

Jon Voisey
Universe Today
Fri, 14 Oct 2011 20:01 UTC
On August 12th, 1883, Mexican astronomer José Bonilla was preparing to study the Sun at the recently opened Zacatecas Observatory. However, the Sun's surface was marred by numerous objects quickly travelling across its disk. Over the course of the day and the next, Bonilla exposed several wet plates to take images of the 447 objects he would observe. They weren't released publicly until January 1st, 1886 when they were published in the magazine L'Astronomie. Since then, UFOlogists have crowed these photographs as the first photographic evidence of UFOs. The chief editor of L'Astronomie passed the observations off as migrating animals, but a new study proposes the observation was due to the breakup of a comet that nearly hit us.

Image
© Jose BonillaFirst photograph of a UFO sighting, taken 12 August 1883 by Jose Bonilla.
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Meteor

Debris of "Doomsday" comet to swing by Earth on Sunday

Mike Wall
CBS News / SPACE.com
Fri, 14 Oct 2011 13:21 UTC
The moment long feared by conspiracy theorists is nearly upon us: The "doomsday comet" Elenin will make its closest approach to Earth Sunday (Oct. 16). Or what's left of it will, anyway.

Image
© NASA/JPL-CaltechTrajectory of comet Elenin
Comet Elenin started breaking up in August after being blasted by a huge solar storm, and a close pass by the sun on Sept. 10 apparently finished it off, astronomers say. So what will cruise within 22 million miles (35.4 million kilometers) of our planet Sunday is likely to be a stream of debris rather than a completely intact comet.

And the leftovers of Elenin won't return for 12,000 years, astronomers say.

"Folks are having trouble finding it, so I think it's probably dead and gone," said astronomer Don Yeomans of the Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

That means it probably won't present much of a skywatching show Sunday, scientists have said.
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Meteor

Did A Comet Cause Solar Explosion? Hardly, Ignorant Experts Say

Mike Wall
SPACE.com
Tue, 11 Oct 2011 15:47 UTC
Image
© SOHO
A huge solar eruption that occurred right after a comet plunged into the sun was likely a coincidence, experts say.

The so-called "sungrazing" comet streaked toward the sun Saturday (Oct. 1) and disintegrated after getting too close. The sun then unleashed a massive eruption of solar plasma known as a coronal mass ejection, which can rocket through space at 3 million mph (5 million kph). But there's no reason to think the two dramatic events were related, scientists said.

"There still remains zero evidence for a link between sungrazing comets and coronal mass ejections (CMEs) that can't be better explained than by simple coincidence," Karl Battams of the U.S. Naval Research Laboratory wrote in a blog post Tuesday (Oct. 4). [Stunning Photos of Solar Flares & Sun Storms]

Solar astronomers with the sun-watching Solar and Heliospheric Observatory agreed.

"The question of whether a sungrazing comet can somehow trigger a coronal mass ejection is an intriguing one," SOHO scientists wrote in a website update this week. "So far, the feeling is that [the] apparent relationship between some comets and some mass ejections is simply one of coincidence."
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Saturn

Saturn's rings tell a comet's tale

Nadia Drake
ScienceNews.org
Tue, 11 Oct 2011 14:15 UTC
Image
© NASA
Ripples testify to 14th century collision

During the 1300s, the Black Death was savaging Europe, England and France were locked in the Hundred Years' War and Chaucer was penning his Canterbury Tales. Meanwhile, more than a billion kilometers away, a comet careened toward Saturn and disintegrated, dropping dusty clouds of debris on the giant planet's iconic rings, creating rippled cometary footprints.

The ripples from that cataclysmic event can still be detected today, electrical engineer Essam Marouf reported October 4 during the joint meeting of the European Planetary Science Congress and the American Astronomical Society's Division for Planetary Sciences.

Marouf, a professor at San Jose State University in California and a member of the Cassini science team, described how the probe beamed radio waves back to Earth through the innermost part of Saturn's C ring, a tenuous inner band in the planet's ring system. The radio waves revealed what Marouf calls a "very unusual kind of addition" to the normal ring structure. "There were highly regular little wiggles that rippled over hundreds of kilometers in a very specific pattern," Marouf says.
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Meteor

First comet found with 'ocean water'

Nicole Casal Moore-Michigan
Futurity
Mon, 10 Oct 2011 14:54 UTC
Comet Hartley
© NASAComet Hartley, as imaged by NASA's EPOXI spacecraft.
For the first time, researchers have detected ocean-like water in a comet - new evidence supporting the theory comets delivered a significant portion of Earth's oceans.

"Life would not exist on Earth without liquid water, and so the questions of how and when the oceans got here is a fundamental one," says Ted Bergin, an astronomy professor at the University of Michigan. "It's a big puzzle and these new findings are an important piece."

The findings are reported in the journal Nature.

Bergin is a co-investigator on HiFi, the Heterodyne Instrument for the Infrared on the Hershel Space Observatory. With measurements from HiFi, the researchers found that the ice on a comet called Hartley 2 has the same chemical composition as our oceans. Both have similar D/H ratios. The D/H ratio is the proportion of deuterium, or heavy hydrogen, in the water. A deuterium atom is a hydrogen with an extra neutron in its nucleus.
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Meteor

Did Comet-Born Oceans Hit Earth?

Jason Palmer
BBC
Wed, 05 Oct 2011 01:00 UTC
Comets Water
Comet Hartley 2 was also the subject of the Deep Impact probe study
Comet Hartley 2 contains water more like that found on Earth than all the comets we know about, researchers say.

A study using the Herschel space telescope aimed to measure the fraction of deuterium, a rare type of hydrogen, present in the comet's water.

Like our oceans, it had half the amount of deuterium seen from other comets.

The result, published in Nature, hints at the idea that much of the Earth's water could have initially come from cometary impacts.

Just a few million years after its formation, the early Earth was rocky and dry; most likely, something brought the water that covers most of the planet today.
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Meteor

Draconid meteor outburst due October 8th from Comet 21P/Giacobini-Zinner

Tony Phillips
Physorg
Wed, 05 Oct 2011 10:11 UTC
On October 8th Earth is going to plow through a stream of dust from Comet 21P/Giacobini-Zinner, and the result could be an outburst of Draconid meteors.

"We're predicting as many as 750 meteors per hour," says Bill Cooke of NASA's Meteoroid Environment Office. "The timing of the shower favors observers in the Middle East, north Africa and parts of Europe."

Image
© N.A.Sharp/NOAO/AURA/NSF Comet Giacobini-Zinner, a fairly frequent visitor to the inner solar system, was captured by the Kitt Peak 0.9-meter telescope on Halloween Night 1998 (UT November 1st, from 02:07 to 03:40). North is up with east to the left. Since the comet was moving across the sky fairly quickly, and since color images are made by combining successive exposures through three different filters, a conventional combination would have either a streaked comet or a set of colored dots for each star. To avoid this, the complete sequence of images, lasting over ninety minutes, was specially processed.
Every 6.6 years Comet Giacobini-Zinner swings through the inner solar system. With each visit, it lays down a narrow filament of dust, over time forming a network of filaments that Earth encounters every year in early October.

"Most years, we pass through gaps between filaments, maybe just grazing one or two as we go by," says Cooke. "Occasionally, though, we hit one nearly head on--and the fireworks begin."

2011 could be such a year. Forecasters at NASA and elsewhere agree that Earth is heading for three or more filaments on October 8th. Multiple encounters should produce a series of variable outbursts beginning around 1600 Universal Time (noon EDT) with the strongest activity between 1900 and 2100 UT (3:00 pm - 5:00 pm EDT).
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Question

Propaganda? 'Comet-shaped' firecloud frightens residents in Arges, Romania


Daniel Irimia
Sat, 01 Oct 2011 11:59 UTC
Frightening phenomenon in the sky of Leresti, a village from Argeş county, Romania. A cloud of fire shaped as a comet, appeared in the evening and terrified the locals.
comet,cloud,romania
Comet-like fire cloud appeared in the sky of Arges county, Romania. NASA: reddish cloud related to Elenin

Comment: "NASA suspected"? No link to anything which could verify that NASA even paid any attention to this cloud in the evening sky is provided by the author, so we are left wondering if his intention was to needlessly alarm people with more hysteria about comet Elenin.

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