Comets


Blackbox

'Ice Comet' To Blame For Crashing Through Roof Of Home?

It Wasn't A Bird. Was It A Plane? A Massive Piece Of Hail? An Ice Comet?

Brush, Colorado -- The mystery continues in Brush after something fell from the sky and crashed through Danelle Hagan's kitchen.

Initially, most involved thought it came from a plane, likely that so-called "blue ice" that sometimes falls from commercial airliners.

There are now several new theories, including the possibility it may have been an "ice comet."

The Discovery Channel is investigating that possibility for an upcoming show set to air this spring.

Construction crews are working to restore Hagan's kitchen. It's an older home, so restoration crews had to clean up some asbestos before crews could start rebuilding.

It happened two months ago, on Nov. 14. Hagan and her 8-year-old daughter were at home in the living room when they heard what they thought was an explosion in the kitchen. It turns out a basketball-sized chunk of ice crashed through her kitchen ceiling -- destroying everything in its path.

Meteor

Sungrazing Comet Alert

The Solar and Heliospheric Observatory (SOHO) is tracking a comet that is about to make a perilous close approach to the sun.

Image
© SOHO
Will the icy visitor survive? Click here for the latest image.

The comet was discovered by Australian amateur astronomer Alan Watson in images taken by NASA's STEREO-A spacecraft.

Telescope

Real Occult Science: Hubble Spots Smallest Comet Vagabond

Image
© Unknown
The largest piece of real estate in the solar system is also the least explored. The solar system's outer rim, the Kuiper Belt, extends from just beyond Neptune's orbit to 5 billion miles from the Sun. It is a debris field of presumably millions of icy bodies left over from the formation of the planets.

First hypothesized 60 years ago by planetary expert Gerard Kuiper, the existence of such an outer comet belt wasn't proven to exist until astronomers began discovering objects in the Kuiper Belt (other than Pluto) in the early 1990s. Now Hubble Space Telescope has stumbled across the smallest thing ever seen in the Kuiper belt.

The previous record holder is 30 miles across. But the interloper Hubble spotted is merely one half-mile across. It would just stretch across the width of New York City's Central Park. In terms of angular size, the object would be the apparent width of a dime located 1/3rd of the way between here and the moon! It is 100 times fainter that Hubble's detection limit.

So how did the Hubble ever uncover such a puny object?

Meteor

Kansas scientists probe mysterious possible comet strikes on Earth

An investigation by the University of Kansas' Adrian Melott and colleagues reveals a promising new method of detecting past comet strikes upon Earth and gauging their frequency

It's the stuff of a Hollywood disaster epic: A comet plunges from outer space into the Earth's atmosphere, splitting the sky with a devastating shock wave that flattens forests and shakes the countryside.

But this isn't a disaster movie plotline.

"Comet impacts might be much more frequent than we expect," said Adrian Melott, professor of physics and astronomy at the University of Kansas. "There's a lot of interest in the rate of impact events upon the Earth. We really don't know the rate very well because most craters end up being destroyed by erosion or the comets go into the ocean and we don't know that they're there. We really don't have a good handle on the rate of impacts on the Earth."

Question

The Puzzle of the Half-Comet, Half-Asteroid

A mysterious object that ejects dust like a comet but orbits like an asteroid could be a new class of object in the solar system.

comsteroid
In 1996, astronomers identified an extraordinary object orbiting the Sun between Mars and Jupiter in a region best known for its asteroids. And yet this body, called 133P, defied description: it had the orbit of an asteroid yet emitted dust like a comet.

Better Earth

Comet Hunter's Last Look at Earth is Haunting

Image
© ESAHigh-resolution image of planet Earth from Rosetta.
This gorgeous image of a blue arc of the Earth against the blackness of space was captured by the Rosetta spacecraft as it swung by our planet.

The European Space Agency mission is on its way to intercept the comet, 67P/Churyumov-Gerasimenko. The ship will deploy a lander onto the comet's surface, the first such attempt to be made.

Click HERE to read the rest of this article on wired.com.

Meteor

Comet Caesar - Dark Comet in 2012?

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© UnknownComet Caesar
When considering what might cause us grief in 2012, few if any researchers consider the start of the Mayan Long Count calendar to have any importance. This is surprising, because the reason for the calendar beginning on August 11 3114BC might contain clues about 2012 itself. After all, the Mayan culture did not exist 5,000 years ago, so either they randomly chose an ancient date on a whim, or an earlier civilization was behind the calendar, and they knew something important occurred on that date.

What could happen in 3114BC, and also in 2012AD? No civilization has lasted that long, so they are unlikely to be man-made events. Any natural events that occur so infrequently on Earth are virtually impossible to predict (volcanic eruptions for example). So that leaves us with astronomical events. The astrology of the pair of dates has been well studied, so we can rule out alignments of the stars and planets. That leaves the Sun, which we barely understand today, and comets. Is there a comet with a periodicity of 5000 years, due to return in 2012? Without any evidence from 3114BC it is impossible to say. Given that we are now near the end of the Mayan 5th age, could their calendar be designed to cover five orbits of a comet? And end catastrophically in 2012?

Most people have not heard of Comet Caesar (it doesn't even have a Wikipedia entry), and hopefully this will remain so. However, if we are to suffer a terrible tragedy in 2012, it is currently my leading candidate, and the purpose of this article is to explain why.

Sherlock

Comets Didn't Wipe Out Sabertooths, Early Americans?

Great Lakes
© Jacques DescloitresNorth America's Great Lakes (pictured in an aerial shot on May 4, 2002) were created during glacial retreats and advances over millions of years—including the brief cold snap called the Younger Dryas, which occurred about 12,900 years ago.
A comet impact didn't set off a 1,300-year cold snap that wiped out most life in North America about 12,900 years ago, scientists say.

Though no one disputes the occurrence of the frigid period, known as the Younger Dryas, more and more researchers have been unable to confirm a 2007 finding that says a collision triggered the change.

The earlier study says the drop in temperature, plus fires from the purported impact, wiped out sabertooths, mastodons, and other giant animals, and may have caused the decline of an early civilization known as the Clovis culture.

The 2007 research was based on a combination of archaeological artifacts and extraterrestrial magnetic grains in soil samples found in a thin layer of sediment throughout North America.

The original team, led by Richard Firestone, a nuclear chemist at Lawrence Berkeley National Laboratory, also found what he said are traces of charcoal and microscopic bits of carbon from intense fires ignited by the collision.

Meteor

North America Comet Theory Questioned

San Jon site
© Vance HollidaySediments at the San Jon site, in eastern New Mexico, contained very low abundances of magnetic spherules said to be evidence of an impact.
No evidence of an extraterrestrial impact 13,000 years ago, studies say.

An independent study has cast more doubt on a controversial theory that a comet exploded over icy North America nearly 13,000 years ago, wiping out the Clovis people and many of the continent's large animals.

Archaeologists have examined sediments at seven Clovis-age sites across the United States, and did not find enough magnetic cosmic debris to confirm that an extraterrestrial impact happened at that time, says the report in the Proceedings of the National Academy of Sciences (PNAS). It is the latest of several studies unable to support aspects of the impact hypothesis.

In 2007, a team led by Californian researchers announced a theory that a comet or asteroid had exploded over the North American ice sheet, creating widespread fire and an atmospheric soot burst followed by a cooling period known as the Younger Dryas.

Sometime after this, the Clovis people, sophisticated large-animal hunters known for their spear points, mysteriously disappeared; the team linked their vanishing to the environmental effects of the proposed impact.

Comment: For a more in-depth view, read: The Younger Dryas Impact Event and the Cycles of Cosmic Catastrophes - Climate Scientists Awakening


Meteor

What (Maybe) Didn't Kill the Dinosaurs: Comets

Comet
© Bettmann CorbisCometary commotion: A new mechanism for how icy bodies get past Jupiter and Saturn suggests that comet showers did not play a big role in Earth's extinctions.
A new model for comet production revises the theory of their origins

The chunks of ice and dust that make their home in the Oort cloud, far beyond the orbit of Pluto, sometimes become dislodged and head into the solar system as streaky comets. Some disruptions, caused by passing stars and other interactions with the Milky Way galaxy, are severe enough to send Oort comets into orbits that buzz or even collide with Earth. New simulations have revealed a novel mechanism for their entry into our part of the solar system, a method that also suggests that comet showers may not have been strongly involved in major extinctions on Earth.

Comet dynamics depend heavily on Jupiter and Saturn: their huge gravitational fields tend to keep objects away from Earth. Comets that manage to skirt Jupiter and Saturn, the conventional thinking goes, had to have originated in the outer reaches of the Oort cloud, where perturbations from outside the solar system can be felt most strongly and are writ large across vast cometary orbits that take hundreds of years to complete. Only during comet showers caused by close stellar passages, the theory holds, have extreme gravitational disruptions brought inner Oort cloud comets into the mix.