Burning Sky
A new University of Colorado Boulder study sheds new light on the conditions after a Manhattan-sized asteroid hit Mexico 66 million years ago (and spelled the doom for dinosaurs).
The research team used models that show the collision...

Burning Sky

A new University of Colorado Boulder study sheds new light on the conditions after a Manhattan-sized asteroid hit Mexico 66 million years ago (and spelled the doom for dinosaurs).

The research team used models that show the collision would have vaporized huge amounts of rock that then blew high above Earth’s atmosphere. An afterwards firestorm of re-entering material would have heated the upper atmosphere for hours at 1,480 degrees Celsius (2,700 degrees Fahrenheit). Every living thing not underground or underwater would have died.

The CU-led team developed a different explanation for the little amounts of charcoal found at the Cretaceous-Paleogene(or K-Pg) boundary, dating to 66 million years ago, when the asteroid struck Earth, and firestorms began. The researchers found that similar studies had corrected their data for changing sedimentation rates. When they did the same for the charcoal data, they actually showed that there was an excess of charcoal, not a deficiency.

“Our data show the conditions back then are consistent with widespread fires across the planet,“ said Robertson, a research scientist, “meaning 100% extinction rates for about 80% of all life on Earth”.

After the asteroid impact, the vaporized rock condensed into sand-grain-sized spheres rising above the atmosphere. As the material re-entered the atmosphere, it would have heated enough the upper atmosphere to trigger an infrared “heat-pulse” so hot to turn the sky to glow red for hours. The radiation from the upper atmosphere reaching Earth’s surface was enough to mean trouble for anyone on the surface igniting tinder, dead leaves and pine needles.

“It’s likely that the total amount of infrared heat was equal to 1 megaton bomb exploding every four miles over the entire Earth”, said Robertson.

The paper published this week on the Journal of Geophysical Research-Biogeosciences: http://bit.ly/YlfDm9

-CHD

Source: http://www.colorado.edu/news/releases/2013/03/27/cu-study-provides-new-evidence-ancient-asteroid-caused-global-firestorm Image credit: Don Davis

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