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TOPIC: Extinction


L

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RE: Extinction
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Crashing Comets Not Likely the Cause of Earth's Mass Extinctions
Scientists have debated how many mass extinction events in Earth's history were triggered by a space body crashing into the planet's surface. Most agree that an asteroid collision 65 million years ago brought an end to the age of dinosaurs, but there is uncertainty about how many other extinctions might have resulted from asteroid or comet collisions with Earth.


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Comet strikes are an unlikely cause of past mass extinctions on Earth, according to computer simulations.
Scientists used the simulations to model the paths of long-period comets, to determine the likelihood of these "dirty snowballs" striking our planet.
The University of Washington, Seattle, research appears in Science journal.


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Comet 'unlikely to wipe out Earth'
The Earth is being protected from comets, thanks to the gravitational pulls of Saturn and Jupiter, according to new research


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Crashing comets not likely the cause of Earth's mass extinctions
Scientists have debated how many mass extinction events in Earth's history were triggered by a space body crashing into the planet's surface. Most agree that an asteroid collision 65 million years ago brought an end to the age of dinosaurs, but there is uncertainty about how many other extinctions might have resulted from asteroid or comet collisions with Earth.
In fact, astronomers know the inner solar system has been protected at least to some degree by Saturn and Jupiter, whose gravitational fields can eject comets into interstellar space or sometimes send them crashing into the giant planets. That point was reinforced last week (July 20) when a huge scar appeared on Jupiter's surface, likely evidence of a comet impact.
New University of Washington research indicates it is highly unlikely that comets have caused any mass extinctions or have been responsible for more than one minor extinction event. The work also shows that many long-period comets that end up in Earth-crossing orbits likely originate from a region astronomers have long believed could not produce observable comets. A long-period comet takes from 200 years to tens of millions of years to make a single orbit of the sun.

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Human activity is driving Earth's 'sixth great extinction event'
Earth is experiencing its "sixth great extinction event" with disease and human activity taking a devastating toll on vulnerable species, according to a major review by conservationists.
Much of the southern hemisphere is suffering particularly badly, and Australia, New Zealand and neighbouring Pacific islands may become the extinction hot spots of the world, the report warns.

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Mission to Mars?
The moon is not enough! That's the thrust of Tom Wolfe's argument in The New York Times, where he laments America's longtime failure to do anything impressive in space. He lays blame for this post-Apollo problem on a lack of big thinkers at NASA.

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Massive volcanic eruptions in ancient times triggered rapid climate change and mass extinctions, by ejecting colossal volumes of greenhouse gases into the atmosphere.

"We have carefully dated minerals contained in the volcanic rocks and shown that only the fastest sequences of eruptions caused significant species extinctions. To understand the long-term climatic and biological effects of the massive injections of greenhouse gas in the atmosphere by modern society we have to understand how climate was affected in the past" - Fred Jourdan of Curtin University, Australia.

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Armageddon
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Posibilele gauri negre produse de acceleratorul de particule LHC, iarna nucleara si potenialul impact cu asteroidul Apophis īn 2029 sunt printre cele mai īnfioratoare ameninari apocaliptice iesite din laboratoarele oamenilor de stiina.
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Anonymous

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Mass extinction
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Researchers unravel mass extinction history, how Earth became habitable

Researchers have uncovered how ancient volcanic eruptions caused global mass extinction and how meteoroid bombardment may have made Earth more habitable.

SCIENTISTS at the University of Leeds, United Kingdom (UK), have uncovered a previously unknown giant volcanic eruption that could have led to global mass extinction 260 million years ago.

The eruption in the Emeishan province of south-west China unleashed around half a million cubic kilometres of lava, covering an area five times the size of Wales, and wiping out marine life around the world.

 

http://www.ngrguardiannews.com/science/article01/indexn2_html?pdate=040609&ptitle=Researchers%20unravel%20mass%20extinction%20history,%20how%20Earth%20became%20habitable



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L

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Medea Hypothesis
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In the past 50 years it has become commonplace to think of Earth as a nurturing place, straining mightily to maintain equilibrium so that life might continue and flourish.
The Gaia hypothesis, named for the ancient Greek goddess of Earth, even put forth the idea that our planet behaves as a kind of giant organism, with its complex systems finely tuned to compensate when one system gets out of kilter.
But actually it is the Gaia view that is out of kilter, says Peter Ward, a University of Washington palaeontologist who has looked closely at conditions that existed during numerous mass extinction events in Earth's history.
In a new book, he suggests the planet ultimately is inhospitable to life, and that life itself might be the primary reason. Rather than Gaia, he invokes the darker Medea from Greek mythology.

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