WSJournal. Asteroid to Narrowly Miss Earth Next Week

Astronomers are keeping a wary eye on a large asteroid expected to narrowly miss hitting Earth next Friday in the closest known approach of a dangerous cosmic object since NASA started tracking such debris.

Next Friday, a 130,000 ton asteroid is set to pass perilously close to earth. WSJ's Robert Lee Hotz runs down what you need to know about the 2012 DA14.

National Aeronautics and Space Administration experts who plotted its trajectory are confident that the primordial rock, weighing an estimated 130,000 metric tons, will pass within "a remarkably close distance" of Earth, nearer than many orbiting communications satellites but far enough away to safely speed past the planet.

At its closest approach—a distance of about 17,200 miles or so away—the asteroid will pass over the eastern Indian Ocean, off Sumatra at 2:24 pm ET Friday, Feb. 15. It will be travelling eight times as fast as a bullet from a high-powered rifle. Depending on local weather, it may be visible from Eastern Europe, Australia and Asia, with binoculars or a moderately powered telescope, space-agency officials said.

"No Earth impact is possible," said asteroid expert Donald Yeomans at the Jet Propulsion Laboratory in Pasadena, Calif. The asteroid poses no danger to the 400 or so satellites in higher orbits around Earth, agency officials said.

Known officially as 2012 DA14, the asteroid is about 150 feet across and was discovered last February by astronomers at the La Sagra Sky Survey operated by the Astronomical Observatory of Mallorca in Spain.

In its journey through space, Earth is bombarded by a hailstorm of comets, meteors and asteroids. Most are motes that sparkle like fireflies as they burn up entering the atmosphere, about 100 tons worth each day. Others have had catastrophic consequences.

Highlighting the risks such asteroids pose to the planet, researchers at the University of California, Berkeley, on Thursday tightened the link between the demise of most dinosaurs 66 million years ago and the impact of a six-mile-wide asteroid that left a 110-mile-wide crater off the Yucatan coast of Mexico. On a geologic time scale, the two events occurred at virtually the same moment, according to new and more precise dating results that they reported in the journal Science.

In this illustration provided by NASA, a graphic depicts the Earth flyby of asteroid 2012DA14.

All told, scientists at NASA's Jet Propulsion Laboratory estimate there are about 500,000 objects about the size of asteroid 2012 DA14 that regularly cross Earth's path. At least one object that size flies close to Earth about every 40 years and one likely hits the planet about once every 1,200 years, astronomers calculate.

They believe the impact of an asteroid that size would generate about 2.5 megatons of blast energy—about twice the explosive power of the B83 nuclear warhead currently deployed in the U.S. military arsenal.