Science Glance
A study last year found unusually high levels of the isotope carbon-14 in ancient rings of Japanese cedar trees and a corresponding spike in beryllium-10 in Antarctic ice.
The readings were traced back to a point in AD 774 or 775, suggesting that during that period the Earth was hit by an intense burst of radiation, but researchers were initially unable to determine its cause.
Now a separate team of astronomers have suggested it could have been due to the collision of two compact stellar remnants such as black holes, neutron stars or white dwarfs.
Black hole collision may have irradiated Earth in eighth century
Federal scientists can again research gun violence
Mark Rosenberg and his colleagues were forced to stop their work at the point of a gun — or at least at the insistence of National Rifle Association.
In 1996, Rosenberg was director of the National Center for Injury Prevention and Control (NCIPC). It was then that Congress, at the behest of the National Rifle Association, stopped federally funded gun-related research by the Centers for Disease Control and Prevention (CDC), which includes NCIPC.
Astronomers Reckon There Are 17 Billion Earth-Size Planets in Our Galaxy Alone
In 1750, British astronomer Thomas Wright published a book An Original Theory or New Hypothesis of the Universe with a diagram showing the stars of our Milky Way, each surrounded by orbiting planets.
But there was no evidence to support his view. "At that point in history," Samuel Arbesman writes in his book The Half-Life of Facts, "this notion was nothing more than a hope, and a somewhat sacrilegious one at that. It was no more than a logical deduction derived from the Copernican notion that our place in the universe need not be a particularly privileged one."
Astronomers report largest structure in universe.
What could be the largest structure yet seen in the observable universe has emerged from data taken during a 12-year survey of the night sky.
The discovery is an apparent cluster of quasars some 4 billion light-years across. If it holds up to further scrutiny, it could challenge a long-held assumption that at the cosmos's largest scales, the physical processes at work and the distribution of matter and energy are the same, regardless of an observer's location.
Statewide quake in California may be possible after all
For decades, scientists have assumed the central portion of California's San Andreas fault acts as a barrier that prevents a big quake in the southern part of the state from spreading to the north, and vice versa. As a result, a mega-quake that could be felt from San Diego to San Francisco was widely considered impossible.
But that key fault segment might not serve as a barrier in all cases, researchers wrote Wednesday in the online edition of the journal Nature.
Study contends Grand Canyon as old as dinosaur era
The awe-inspiring Grand Canyon was probably carved about 70 million years ago, much earlier than thought, a provocative new study suggests - so early that dinosaurs might have roamed near this natural wonder.
Using a new dating tool, a team of scientists came up with a different age for the gorge's western section, challenging conventional wisdom that much of the canyon was scoured by the mighty Colorado River in the last 5 million to 6 million years.
Antarctic microbes thrive without sunlight
In a world without sunlight, microbes still seem to thrive in an Antarctic lake iced over for at least 2,800 years, biologists report.
Lake Vida, a chilly brine pool covered by more than 50 feet of ice, resides in East Antarctica. Biologists led by Alison Murray of the Desert Research Institute in Reno report that 2005 and 2010 core samples reveal aquatic microbes thrive in its yellowish waters, in this week's Proceedings of the National Academy of Sciences.
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