Incoming! Meteor Crash in Peru?

[Gaby]

There are two types of physical body which can hit the Earth, namely, comets and asteroids. In the past ancient people had seen and recorded comets; the bright gaseous plume which is illuminated by the sun was often described as a bow, or sword, or arm in the sky. There are no obvious records of asteroids, small dark bodies which are effectively invisible without a telescope, and not that easy to spot even with large telescopes.

This reminded me of an article of Nature Magazine

Published online: 18 October 2004; | doi:10.1038/news041018-3

Unseen comets may raise impact risk for Earth

Mark Peplow

Thousands of dark objects could be hiding in our Solar System

The Solar System could be teeming with almost invisible comets,
according to some astronomers' calculations. If they are right, such
extra comets would significantly increase the risk of a catastrophic
impact with Earth.These objects have never been observed, but the
astronomers argue that 'dark comets' provide a likely explanation for
an astronomical puzzle: we can only see a tiny fraction of the comets
that theory predicts.Astronomers think that many comets come from the
Oort cloud, a field of billions of icy objects that lies up to
100,000 times farther away from the Sun than the Earth does and marks
the outer boundary of our Solar System. The icy objects are sometimes
driven towards the Sun by gravitational tides generated by the
shifting masses of stars in our Galaxy. When this happens they become
comets, orbiting the Sun every 20 to 200 years on paths that lie at
an angle to the planets' orbits. Given the size of the Oort cloud,
astronomers have calculated that there should be about 3,000 comets
in these orbits, 400 times more than are actually observed.
The common explanation for this discrepancy is that the comets
quickly disintegrate into smaller lumps after just one or two orbits,
says Bill Napier, a recently retired astronomer who worked at the
Armagh Observatory, Northern Ireland. But his mathematical model now
suggests that, if this were true, the debris should cause many more
major meteorite showers on Earth than we see, perhaps up to 30 every
year.In a paper to be published in the Monthly Notices of the Royal
Astronomical Society1, Napier concludes that the predicted comets are
out there after all; we just cannot see them. Little fluffy
cloudsNapier worked with Chandra Wickramasinghe, an astronomer at
Cardiff University in Wales, to explain the comets' invisibility.
Wickramasinghe has suggested that Sedna, the most distant body
identified in our Solar System, could have an orbiting twin that is
dark, fluffy and made of tarry carbon compounds (see "Sedna 'has
invisible moon'"). As Sedna may be a member of the Oort cloud, Napier
thinks that other members of the cloud could be equally dark. Once
ejected, the tarry comets would simply suck up visible light, he
says, remaining cloaked in darkness. "Photons go in, but they don't
come out.""It's an intriguing possibility," says Alan Fitzsimmons, an
astrophysicist at Queen's University of Belfast in Northern
Ireland. "But while we have seen dark objects before, Bill is
proposing something much, much darker than anything we've ever
detected."NASA's Stardust probe, which is bringing back samples of
dust from the comet Wild 2, lends some support to Napier's idea. In
June this year it reported finding lots of tarry carbon compounds
spraying from the comet2.Infrared challengeThe dark comets would
present a major challenge to astronomers searching the skies for
objects that might collide with the Earth. "They're so black you
can't see the damn things," says Napier. "These things will just come
out of the dark and hit you with no warning. It looks as if we're
dealing with a substantial impact hazard that people haven't clicked
into yet."
However, although they reflect almost no visible light, the dark
comets should give out a tiny glow of heat, visible as infrared
radiation. The infrared Spitzer Space Telescope, which has been
operating from Earth orbit for just over a year, has not seen any
dark comets. But this could be because it focuses on very small,
distant parts of the sky, says Napier. Fitzsimmons disagrees, saying
that if these objects existed in the numbers proposed by Napier,
either Spitzer or near-Earth object surveys such as Spacewatch, based
at the University of Arizona in Tucson, would have picked them up by
now.A new space telescope might provide the answer. Earlier this
month, NASA announced that it would launch an orbiting infrared
telescope called the Wide-field Infrared Survey Explorer (WISE) in
2008, which will map much wider areas of the sky. Given enough time,
it should be able to detect the dark comets, says Napier.



References 1. Napier W. M., Wickramasinghe J. T. & Wickramasinghe
N. C. Mon. Not. R. Astron. Soc, published online, doi:10.1111/j.1365-
2966.2004.08309 (2004). 2. Kissel J., Krueger F. R., Silen J. &
Clark B. C. Science, 304. 1774 - 1776 (2004). | Article | PubMed |
ISI | ChemPort

 

[Beorn]

Just posted on Yahoo news: hxxp://news.yahoo.com/s/space/20070927/sc_space/meteoritecrashbreedsmasshysteria

All I can say is 'Mass Hysteria'? They've got to be kidding!

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On what started as a normal Saturday night one week ago, residents of a small, remote Peruvian town saw a bright light streak across the sky, heard a resounding bang and suddenly found themselves at the center of a media frenzy.
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Initial suspicions of an airplane crash quickly spiraled into widespread reports that a meteorite had plummeted to Earth and left a smoking, boiling crater whose supposedly noxious fumes were reported to have sickened curious locals who went to peer at the hole.

Despite doubts expressed by geologists that the crater was actually caused by a meteorite and firm explanations that a meteorite would not even emit fumes and that the "sickness" was likely a case of mass hysteria, numerous onlookers far and wide were fascinated by the idea that this event could be some real-life "Andromeda Strain" (the 1969 novel by Michael Crichton), where a mysterious rock falling to Earth from outerspace made anyone who went near it ill.

So what is it about things falling from the sky that fills us with such fear that we can make ourselves sick with panic?

Mass hysteria

Media reports of the number of locals afflicted by a "mysterious disease"—with symptoms such as nausea, headaches and sore throats—after visiting the crater figured in every news article about the Aug. 15 event, with some reporting that as many as 600 people had fallen ill.

But doctors who visited the site told the Associated Press they found no evidence that the crater had actually sickened such a large number of people.

If noxious fumes did emanate from the crater, they were most likely the result of a hydrothermal explosion that could have actually formed the crater, or were released from the ground when the meteorite struck, if in fact one did, according to many geologists.

Arsenic is found in the subsoil in that area of Peru and often contaminates the drinking water there, according to Peruvian geologists quoted on Sept. 21 by National Geographic News. Arsenic fumes released from the crater could have sickened locals who went to look, said one geologist who examined the site.

Some health officials suggest that the symptoms described by the locals, the large number of people reporting symptoms, and the apparently rapid spread have all the hallmarks of a case of mass hysteria.

"Those who say they are affected are the product of a collective psychosis," Jorge Lopez Tejada, health department chief in Puno, the nearest city, told the Los Angeles Times.

This psychosis could have begun as a result of fear of the meteorite and the mysterious "disease" on the part of the residents and spread as official and media reports seemed to confirm it and give it credence.

"The Peruvian event seems to be a rare case where we may be witnessing collective anxiety that is approaching near hysteria," said Benny Peiser, a social anthropologist at John Moores University in England. "The major[ity] of the affected Peruvian town hinted that some of the mass anxiety is due to fear of imminent impacts and psychological stress which is not surprising given the premature speculation and media hype."

Fear of outer space

Fear of a meteorite impact is nothing new—humans have long looked to the heavens with a wary eye.

"The fear of cosmic disaster, in particular cometary impacts, has existed in all cultures for millennia," Peiser told SPACE.com

But the space age revealed just how many dangers, including comets, meteors, asteroids, and cosmic rays, await us in the final frontier.

"Only since the late 20th century, humankind has become aware of the risk posed by asteroids and comets," Peiser said. "Unfortunately, this risk has been wildly exaggerated by popular culture."

Our curiosity and fear of impact events has increased their coverage by the world media, Peiser says, which in turn has increased the number of meteorite impact reports, even when the evidence doesn't point that way.

"In recent years, there have been numerous cases where alleged meteorite falls were linked to mysterious explosions on the ground—only to be proven wrong," Peiser said. "One of the main reasons for the significant increase of such claims is almost certainly due to the growing media interest in the cosmic impact risk. It is part of human nature— and extremely tempting for the news media—to hype any event that initially looks mysterious."

While this fear is normal and understandable, it's been blown out of proportion so that the public thinks that impact risks are higher than they are, Peiser argues.

"Most people are simply not aware that we are making enormous progress in finding and identifying the population of Near Earth Objects and that the impact risk is thus diminishing year by year," Peiser said.

And when meteorites have struck, they have never carried any hint of some mysterious space disease.

"I don't know of any known record of a meteorite landing that emitted odors so noxious that people got sick from it," said geologist Larry Grossman of the University of Chicago.

So much for the Andromeda Strain.
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Jeff