Science briefs

Earth at its farthest from the sun

Earth will be at its farthest distance from the sun at 11 a.m. today. Astronomers call this point "aphelion."

On its annual journey, Earth travels an elliptical path around the sun, rather than a circle. The average distance between Earth and the sun is about 92.918 million miles, according to the Pisgah Astronomical Research Institute near Asheville. Today, Earth will be about 1.5 million miles farther from the sun than average.

Humans are a menace to caribou

Humans are a much bigger problem than wolves for a caribou herd in the oil sands area of Alberta, Canada, scientists from the University of Washington reported in Frontiers in Ecology.

Studies of scat of moose, caribou and wolves in the area showed that caribou accounted for only 10 percent of the animals consumed by wolves. Eighty percent of the wolves' diet was deer, with moose making up the remainder. Wolves' preference for deer, the researchers conclude, draws them away from the areas where caribou thrive.

But the oil sands contain the second largest reserve of petroleum in the world, which brings humans to the area. By looking at hormone levels in caribou scat, the scientists found that caribou nutrition was poorest and psychological stress highest when humans were active in the area. When oil crews left, the animals relaxed and nutrition improved. New York Times

CMV saliva test for babies is faster

A new test offers a rapid, inexpensive and highly accurate method for screening newborns for cytomegalovirus, which can cause permanent hearing loss, researchers reported in The New England Journal of Medicine.

Though one in 150 babies are born infected with cytomegalovirus - part of the herpes virus family - current tests are not effective for widespread screening, the scientists said. The new test does not require the culturing of blood samples; it employs saliva, easily obtained by swabbing the inside of a baby's mouth. New York Times

Asteroid skirts the Earth

An asteroid the size of a tour bus streaked harmlessly past Earth last week, passing within 7,600 miles. The relatively small space rock made a hairpin turn around the planet, sailing high over the southern Atlantic Ocean.

Astronomers never doubted it would miss. But given the vastness of the universe, 7,600 miles is practically a stone's throw away, about three times the distance between New York and Los Angeles.

The asteroid, dubbed 2011 MD, was initially mistaken by astronomers for space junk because it was so small, at 15 to 60 feet wide. Later observations found it was an asteroid that would have burned up in the atmosphere if it had reached Earth.

Asteroids of this size typically brush by Earth every six years. A smaller one came even closer, passing within 3,500 miles this year.

"We're just waking up to the fact that Mother Nature has been shooting these things across the bow for millennia," said Don Yeomans, who heads the program that tracks potentially dangerous space rocks atNASA's Jet Propulsion Laboratory in Pasadena, Calif. Associated Press