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sara e. pratt

Moon could have formed from Earth after all: Reviving and revising the giant impact theory

Scientists are revisiting the age-old question of how Earth’s moon formed. New models indicate that it could have been born from the Earth following a giant collision after all.

The idea of a moon-forming collision is not new. The giant impact theory — the idea that a catastrophic collision about 4.5 billion years ago between Earth and a protoplanet about half Earth’s size created a disk of molten rock, gas and debris that consolidated to form the moon — was first set forth in the mid-1970s.

04 Feb 2013

Benchmarks: January 1, 1960: The Discovery of "Extinct Radioactivity" The quest to date the elements that formed the solar system

On June 30, 1918, Leo Kern saw a fireball blaze across the sky above his farm near Richardton, N.D., lighting up the night sky as if it were daytime and then exploding with a deafening boom that shook houses and rattled windows. Kern ducked behind a telegraph pole as fragments that sounded like “whistling bullets” struck his barn, he later reported to geologist T.T. Quirke of the University of Minnesota. What Kern and other witnesses all over  the southwestern corner of the state had seen was a 90-kilogram meteor entering Earth’s atmosphere and breaking up 100 kilometers above the surface. Kern had no way of knowing it at the time, but he had also witnessed the arrival of a message from the dawn of the solar system — one that scientists wouldn’t decode for another 42 years. 
 
01 Jan 2013

Down to Earth With: Lawson Brigham

Lawson Brigham, a Distinguished Professor of Geography and Arctic Policy at the University of Alaska at Fairbanks and retired U.S. Coast Guard captain, has worn many hats in his career. He has been the deputy director and Alaska Office director of the U.S. Arctic Research Commission in Anchorage; chair of the Arctic Marine Shipping Assessment of the Arctic Council, an intergovernmental forum of the eight Arctic nations; vice chair of the Arctic Council’s working group on Protection of the Arctic Marine Environment; and a contributing author to the Arctic Climate Impact Assessment.

18 Oct 2012

Venus in transit to the transit

5 June 2012 - Reader Elizabeth Talley snapped an iPhone photo of an ice ring around the sun yesterday afternoon in Port Charlotte, Fla., and unexpectedly also captured this image of Venus as it heads toward this evening’s rare celestial event — a transit of the sun. The seven-hour transit, during which the planet will appear as a small black disk moving across the solar face, will begin at 6:03 p.m.

05 Jun 2012

Carbon and the city: Tracking emissions from megacities

Sometime in the first century A.D., Rome’s population passed 1 million. It took more than 18 centuries for a city to surpass the 10 million mark, which both New York City and Tokyo did by 1950. Just six decades later, the world now has about 20 such “megacities” with populations of 10 million or more, including the largest, Tokyo, with a population of 35 million.

22 May 2012

Earliest instrumental temperature record recovered in Italy

 

In the aftermath of the flood that struck Florence, Italy in 1966, records from the national library became scattered, including the earliest known instrumental temperature records collected by the Medicis in the 1600s. Recently, the temperature records were rediscovered and analyzed for the first time, giving researchers new insight into climate during the Little Ice Age. 

10 May 2012

Tree-climbing hominin with opposable toes co-existed with Lucy

When Lucy and other Australopithecines were walking around Ethiopia 3.4 million years ago, they may have encountered another hominin species that still climbed trees and also walked, but with a gait more like an ape than their bipedal neighbors. The tantalizing new discovery of a few fossil foot bones shows that at least one species retained an opposable big toe, one million years after the grasping feature was thought to have disappeared.

29 Mar 2012

Danger in paradise: The hidden hazards of volcano geotourism

In November 2000, rangers at Hawaii Volcanoes National Park made a gruesome discovery. The bodies of a man and a woman, in an advanced state of decomposition, were found near the site where lava from the Kilauea eruption flows into the sea, sending up plumes of scalding white steam. The area, aptly named the Eruption Site, is littered with chunks of tephra, a glassy volcanic rock, which are formed and ejected violently into the air when the 2,000-degree-Celsius lava is quenched by seawater.

19 Mar 2012

Benchmarks: March 1961: Project Mohole undertakes the first deep-ocean drilling

Since its inception in the 1960s, the ocean drilling program — an international research program that explores the world’s ocean basins — has logged hundreds of thousands of hours of ship time traveling the world’s oceans, drilling boreholes and retrieving cores of sediment and rock that have revealed Earth’s deep history and structure.
 
05 Mar 2012

Blogging On Earth: Humans acidifying ocean at unprecedented rate

Human emissions of carbon dioxide are currently acidifying the oceans at a rate unprecedented in the last 300 million years — since well before the dinosaurs evolved — according to a study published today in Science. More acidic water can dissolve the shells of many marine organisms, including reef- and shell-building species, such as clams, oysters and corals, as well tiny organisms that form the base of the food chain.

01 Mar 2012

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