Should we be worried that a space rock half the size of a football field is hurtling toward Earth?
Rest easy, NASA astronomers said Thursday in a special teleconference about the object.
There is no chance that asteroid 2012 DA14, perhaps 150 feet in diameter, will collide on Friday with our planet.
But in cosmic terms, oh, it's going to be a close shave.
The asteroid will make a record close approach of a natural solar system body that has been predicted in advance.
"It will pass within 17,200 miles of the Earth's surface on Feb. 15. However this asteroid's orbit is so well known that we can say with confidence ... no Earth impact is possible," said Donald Yeomans, manager of the Near-Earth Object office at NASA's Jet Propulsion Laboratory in Pasadena, Calif. The office monitors objects that enter the Earth's vicinity that may be an impact threat.
"Since regular sky surveys began in the 1990s, we've never seen an object this big get so close," Mr. Yeomans said.
And it will be moving right along.
"The asteroid will pass the Earth at about 5 miles per second," said Eric Fischer, a longtime amateur astronomer and satellite observer who lives in Hampton. "At that speed, it could travel from Monroeville Mall to the Pittsburgh airport in about four seconds."
The asteroid was discovered Feb. 23, 2012, by the La Sagra Sky Survey operated by the Astronomical Observatory of Mallorca, Spain. An impact by an object the size of 2012 DA14 would not cause global destruction, but it would level a city.
"A similar-sized body is believed to have struck Siberia in 1908. The resulting explosion flattened trees over an area larger than Pennsylvania." Mr. Fischer said.
A collision with Earth would release the energy equivalent of 2.4 million tons of TNT and cause widespread destruction over 750 square miles.
While the asteroid is not such a threat for the foreseeable future, it still has a slim chance during Friday's flyby of making an impact on our satellites.
"It will pass 5,000 miles inside the ring of communications and weather satellites in geosynchronous orbit" some 22,300 miles above Earth, Mr. Yeomans said. The likelihood of a collision is extremely remote, but "we are working with satellite providers to make them aware."
The asteroid's closest approach will occur at 2:24 p.m. Eastern Standard Time over Indonesia, Mr. Yeomans said. That's long before sunset in the Pittsburgh area. Residents of Eastern Europe, Asia and Australia, where it will be dark, will have the best chance to see 2012 DA14.
For the general public, the diminutive asteroid will pass unseen. Accomplished amateur astronomers locally, however, may be able to spot it.
"The asteroid will only be visible through small telescopes of several inches diameter," Mr. Fischer said. "This asteroid will appear as a tiny point of light moving slowly against the background stars."
Weather permitting, the Clay Center Observatory in Brookline, Mass., will offer a view. It will stream real-time, high-definition video of the asteroid's pass from 6 p.m. Friday until 4 a.m. Saturday via the observatory's Ustream channel at www.ustream.tv/channel/clay-center-observatory.
Because of the effects of our planet's gravity, 2012 DA 14 will have its orbit about the sun reduced from a little more than a year to about 317 days. Its next significant close approach will be Feb. 15, 2046, when it is predicted to pass within 740,000 miles.
Pete Zapadka: firstname.lastname@example.org; 412-263-1857. Twitter: @pzapadka. First Published February 10, 2013 5:00 AM