BATAVIA, Ill., Sept. 17 (UPI) -- The most powerful sky-mapping machine ever created has captured and recorded light from 8 billion years ago, U.S. researchers say.
After eight years of planning and construction by scientists, engineers, and technicians on three continents, the Dark Energy Camera has recorded its first images, scientists at the U.S. Department of Energy's Fermi National Accelerator Laboratory in Illinois reported.
As part of the Dark Energy Survey, the images may help answer one of the biggest mysteries in physics -- why the expansion of the universe is speeding up.
"The achievement of 'first light' through the Dark Energy Camera begins a significant new era in our exploration of the cosmic frontier," James Siegrist, associate director of science for high energy physics with the U.S. Department of Energy, said.
"The results of this survey will bring us closer to understanding the mystery of dark energy, and what it means for the universe."
The Dark Energy Camera, about the size of a phone booth, was constructed at Fermilab.
"The Dark Energy Survey will help us understand why the expansion of the universe is accelerating, rather than slowing due to gravity," Brenna Flaugher, project manager and scientist at Fermilab, said. "It is extremely satisfying to see the efforts of all the people involved in this project finally come together."
The camera is able to see light from more than 100,000 galaxies up to 8 billion light years away in each snapshot.
Study: Pollution costs underestimated
HEIDELBERG, N.Y., Sept. 17 (UPI) -- Using a faulty analytical model has led the U.S. federal government to significantly underestimate the costs of carbon pollution, a study suggests.
Writing in the Journal of Environmental Studies and Sciences, researchers said the model used by the government is incomplete because it all but ignores the economic damages climate change will inflict on future generations.
Without properly accounting for pollution costs, natural gas appears to be the cheapest generation option for new power plants, but that's a faulty assumption, the study authors said.
"It turns out that the price we now pay for energy is much higher than what shows up on our electric bills or the tab at the gas pump," Laurie Johnson, chief economist in the climate and clean air program at the Natural Resources Defense Council, said.
Considering the economic costs of carbon and other pollutants from fossil fuel generation, the researchers said, building new electricity generation capacity using wind and solar power would be more cost effective than either natural gas or coal.
"With approximately 40 percent of all carbon emissions in the United States coming from power plants, the economic advantages of clean electricity sources are significant," Johnson said.
Loss of sea ice threatens arctic seals
SEATTLE, Sept. 17 (UPI) -- An arctic seal species is threatened as two thirds of sea ice with enough snow cover for them to reproduce is at risk of disappearing, U.S. researchers say.
Scientists as the University of Washington say the ringed seal, under consideration for threatened species status, needs to build caves to rear its young in snowdrifts on sea ice.
"It's an absolute condition they need," atmospheric science Professor Cecilia Bitz said in a university release.
Snow depths must average at least 8 inches to enable drifts deep enough to support the caves, the researchers said.
But as sea ice, the platform that allows the snow to pile up, disappears with climate change, it reduces the area where the seals can raise their pups.
With disappearing sea ice, snow in the fall -- the heaviest snowfall period -- will fall into ocean water instead of piling up on ice, the researchers said.
The area of the arctic that received at least 8 inches of snow will decrease by almost 70 percent this century, they estimate, and with insufficient snow depth seal caves won't hold up.
Basic solar system measure redefined
BEIJING, Sept. 17 (UPI) -- Astronomers meeting in Beijing say they've agreed on a new definition of the fundamental unit of distance between objects in the solar system.
The "astronomical unit," defined as the distance between the sun and the Earth, is now set at exactly 149,597,870,700 meters (163,602,220,800.53 yards or 92,955,807.27 miles), the meeting of the International Astronomical Union declared.
That's 9 meters, or about 30 feet, more than the previously agreed distance, which was based on the average distance between Earth and the sun and was also tied to the mass of the sun.
But the sun is constantly losing mass as it radiates energy, which technically changes the value of the AU over time, astronomers said.
"The old definition was good when we were not able to measure distance precisely in the solar system," Sergei Klioner of the Technical University of Dresden, Germany, who has been calling for the change since 2005, told NewScientist.com.
But scientists can now make precise measurements of astronomical distances using lasers and space probes.
"I've been teaching celestial mechanics for 20 years and it was always a pain to explain the old definition," Klioner said. "It was clear that it was unnecessarily complicated."