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Jan. 18, 2013 at 6:56 PM
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Fireball lights up California skies

SAN FRANCISCO, Jan. 18 (UPI) -- Early risers in Northern California reported a fireball lighting up the predawn sky Thursday, and began calling in reports of a possible meteor.

Reports staring coming in about 5:25 a.m. PST from people across California and as far away as Fernley, Nev., about 30 miles east of Reno, the San Francisco Chronicle reported.

"Wow, what a sight to have seen!" David Rivas of Seaside in Monterey County wrote in an email to the newspaper.

Rivas said he and his wife notice the celestial light show while driving north of Monterey.

"It first appeared as a quick movement of sorts, maybe similar to a shooting star or quick lightning strike off to the east," he said.

Then, he said, "it grew into something shaped like a giant orange crayon."

The area had been treated to another cosmic light show Oct. 17 when a meteor lit up the skies and several chunks of it were later found in the Novato, Calif., area of Marin County.

LEDs with more natural light developed

ATHENS, Ga., Jan. 18 (UPI) -- U.S. researchers say they've developed an LED that emits a warm light rather than the bluish, cold light that's held LEDs back from use in indoor lighting.

University of Georgia scientists say the LED is the first that emits a warm white light, using a single light emitting material, or phosphor, with a single emitting center for illumination.

"Right now, white LEDs are mainly used in flashlights and in automotive lamps, but they give off a bluish, cool light that people tend to dislike, especially in indoor lighting," physics Professor Zhengwei Pan said. "Our material achieves a warm color temperature while at the same time giving highly accurate color rendition, which is something no single-phosphor-converted LED has ever been shown to do."

Warm white light can be achieved with a blue LED chip coated with light emitting materials but combining the source materials in an exact ratio can be difficult and costly, Pan said -- and the resulting color often varies because each of the source materials responds differently to temperature variations.

"The use of a single phosphor solves the problem of color stability because the color quality doesn't change with increasing temperatures," co-researcher Xufan Li, an engineering doctoral student, said.

There are still design and production hurdles to be overcome before the material is used to light homes, businesses and schools.

"We still have more work to do, but the color temperature and rendition that we have achieved gives us a very good starting point," Pan said.

Database of volcanic eruptions created

BRISTOL, England, Jan. 18 (UPI) -- Details of about 2,000 major volcanic eruptions occurring over the past 1.8 million years are available in a new open access database, British researchers say.

The database of Large Magnitude Explosive Eruptions will provide crucial information to researchers, civil authorities and the general public alike, they said.

Compiled by an international team headed by researchers at Bristol University, with support from the British Geological Survey, the LaMEVE database provides rapid, searchable access to information available for large volcanic events of magnitude 4 or greater.

The database will provide knowledge of past behavior of volcanoes to help produce risk assessments of the hazards of modern explosive events, a Bristol release said Friday.

"Magnitude 4 or greater eruptions -- such as Vesuvius in A.D. 79, Krakatoa in 1883 and Mount St. Helens in 1980 -- are typically responsible for the most loss of life in the historical period," research leader Sian Crosweller of Bristol's School of Earth Sciences said.

The database contains information on magnitude, explosive levels, deposit volumes, eruption dates and rock types.

"The long-term goal of this project is to have a global source of freely available information on volcanic hazards that can be used to develop protocols in the event of volcanic eruptions," principle investigator Stephen Sparks said.

Telescope may turn to dark matter hunt

LONDON, Jan. 18 (UPI) -- A NASA space telescope has seen hints of evidence for the so-called dark matter that makes up an estimated 85 percent of the universe's mass, researchers say.

In one of physics' greatest ongoing mysteries, evidence for the existence of dark matter comes only from its gravitational effects. It cannot be directly observed because it interacts only very weakly with light or normal matter.

The Fermi space telescope, designed to catch gamma rays -- the universe's highest-energy light -- has produced hints of its existence in gamma rays at the center of the Milky Way.

Fermi project scientist Julie McEnery said that has sparked a call for proposals to change the telescope's main mission from its current examination of the spinning neutron stars known as pulsars and supermassive black holes.

"Some of the motivation to explore different observation strategies is from this tentative signal at the center of the galaxy, but I think even if that wasn't there we would want to go to our community of scientists and ask them, 'based on what you've seen in the data, should we do something different?'" she told the BBC.

Physicists say they believe dark matter consists of relatively heavy particles which, when they encounter one another, "annihilate" with a flash of high-energy light that the Fermi telescope could see.

Seeing evidence for dark matter at the center of the galaxy would be the most important result the Fermi mission could produce, McEnery said.

"We'll have found something that physicists and astronomers have been looking for for decades -- understanding not just where dark matter is but something more fundamental about its nature, so this is something that we in the Fermi project are keen to pursue," she said.

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