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Sun, 25 Aug 2019
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Comets

Star

Exploring The Comets Of Sol

Since 1986, four different comets -- Halley, Borrelly, Wild 2 and Tempel 1 -- have been examined in impressive detail by a wide variety of American, European and Russian spacecraft, including one that has actually returned a small dust sample to Earth and another that crashed a large piggyback spacecraft into a comet's nucleus to try and reveal some of its subsurface structure. And in 2014, the still more ambitious European "Rosetta" mission will rendezvous with the nucleus of a fifth comet (Churyumov-Gerasimenko), examine it from just 25 kilometers away (or less) for over a year and a half, and even drop a small survivable lander onto the nucleus' surface.

All this attention is entirely justified, given the fact that comets are the only preserved pieces of the "planetesimals" that were made by accretion out of the initial dust, ices and gas of the primordial pre-Solar System nebula itself, and which in turn merged together to form the planets.

Telescope

Taiwanese star-gazer discovers comet

It was so faint amid the star-freckled blackness that professional star-gazer Lin Chi-sheng missed it as he photographed the heavens from Lulin Observatory, Nantou County, earlier this month.

Luckily, Lin's camera, recording time-lapse images of space through the observatory's telescope, didn't miss it -- a mighty chunk of ice and rock "a few kilometers" in diameter and hurtling toward Earth: "Asteroid C/2007-N3."

Arrow Down

July 16, 1862: This Comet Has Earth Written All Over It

1862: American astronomer Lewis Swift discovers the presence of a large comet that will soon bear his name. Three days later, another American astronomer, Horace Tuttle, makes the same sighting. So this heavenly body comes down to us as the Comet Swift-Tuttle.

Based on their observations, and those of other astronomers who began tracking the comet's highly elongated orbit, it was calculated that Swift-Tuttle would make its next appearance during the 1980s. They were close. Japanese astronomer Tsuruhiko Kiuchi rediscovered the comet in 1992.

Telescope

Comet LINEAR Graces the Northern Sky

Comet LINEAR (C/2006 VZ13), now crossing through Draco and Boötes, has far exceeded expectations. It was originally predicted to peak in brightness around magnitude 10, a pleasant spectacle for people who enjoy viewing faint comets through telescopes. But the latest magnitude estimates range from 7.5 to 8.0, making it an easy sight through 10×50 binoculars in a dark, transparent sky.

Telescope

Comet chemistry theory put to the test

A dying comet has prompted astronomers to take issue with a mainstream theory about the impact of "space weather" on these enigmatic wanderers of the Solar System.

Magnify

Comet theory collides with Clovis research

A comet theory put forth by a group of 25 geo-scientists suggests that a massive comet exploded over Canada, possibly wiping out both beast and man around 12,900 years ago, and pushing the earth into another ice age.

©USC
Site where most pre-Clovis work is being done.

University of South Carolina archaeologist Dr. Albert Goodyear said the theory may not be such "out-of-this-world" thinking based on his study of ancient stone-tool artifacts he and his team have excavated from the Topper dig site in Allendale, as well as ones found in Georgia, North Carolina and Virginia.

Star

Younger Dryas Cometary Impact AGU Press Conference, Acapulco, Mexico, May 23, 2007

Investigations of a buried layer at sites from California to Belgium reveal materials that include metallic microspherules, carbon spherules, nanodiamonds, fullerenes, charcoal, and soot. The layer's composition may indicate that a massive body, possibly a comet, exploded in the atmosphere over the Laurentide Ice Sheet 12,900 years ago. The timing coincides with a great die-off of mammoths and other North American megafauna and the onset of a period of cooling in Northern Europe and elswhere known as the Younger Dryas Event. The American Clovis culture appears to have been dramatically affected, even terminated, at this same time. Speakers discuss numerous lines of evidence contributing to the impact hypothesis. The nature and frequency of this new kind of impact event could have major implications for our understanding of extinctions and climate change.

Part 1

Bizarro Earth

The Younger Dryas Impact Event and the Cycles of Cosmic Catastrophes - Climate Scientists Awakening



The eagle screams,
And with pale beak tears corpses. . . .
Mountains dash together,
Heroes go the way to Hel,
And heaven is rent in twain. . . .
All men abandon their homesteads
When the warder of Midgard
In wrath slays the serpent.
The sun grows dark,
The earth sinks into the sea,
The bright stars
From heaven vanish;
Fire rages,
Heat blazes,
And high flames play
'Gainst heaven itself"

R.B. Anderson, "Norse Mythology," 1875

NASA seems to spend a lot of time looking for and thinking of ways to divert errant asteroids that might possibly hit earth. However, they keep reassuring the public that the probability of actually being hit by an asteroid is extremely small. So why all the attention?

Bizarro Earth

Did a comet zap the woolly mammoths? Scientists posit huge explosion over Canada 12,900 years ago

There are intriguing new clues in the mystery of how the woolly mammoth met its demise in North America more than 10,000 years ago.

For decades, scientists have debated whether the giant, elephant-like beasts were driven to extinction by the arrival of overzealous human hunters or by global warming at the end of the Pleistocene era, the last great Ice Age. Some say it was a combination of the two.

Recently, a group of more than two dozen scientists offered a new explanation. They have found signs that a comet -- or multiple fragments of one -- exploded over Canada about 12,900 years ago with the force equivalent to millions of nuclear weapons. That unleashed, they said, a tremendous shock wave that destroyed much of what was in its path and ignited wildfires across North America.

Gear

Let's blame humans for everything: Humans and not comet (gawd forbid) had help finishing off woolly mammoths

Humans might have finished off the woolly mammoths, but the genetics of the giants apparently helped them decline well beforehand, scientists now find.

The woolly mammoth (Mammuthus primigenius) was coated in hair up to 20 inches long and possessed extremely long, curved tusks up to 16 feet in length. The giants lived for tens of thousands of years, apparently going extinct roughly 12,000 years ago, around the end of the last ice age.

For years, scientists suspected that ancient human tribes hunted the mammoths and other ice age giants to oblivion. Recent research seems to contradict this notion, however - for instance, a comet or tuberculosis may have helped kill off the American mastodons (Mammut americanum), closely related to mammoths.