Asteroid to make closest Earth fly-by on record this Friday

Asteroid 2012 DA14 will pass very close to the Earth on Friday (February 15, 2013), so close that it will pass inside the ring of geosynchronous weather and communications satellites.

NASA's Near-Earth Object Program Office is predicting there is no chance that the asteroid might be on a collision course with the Earth. Nevertheless, the flyby will provide a unique opportunity for researchers to study a near-Earth object up close.

Based on its brightness, astronomers estimate that it is only about 45 meters (150 feet) across, just under half the length of a soccer pitch.

The last time a space rock of that size impacted earth was on June 30, 1908 when a large meteoroid or comet fragment exploded at an altitude of 5–10 kilometres (3–6 mi) above Tunguska, Krasnoyarsk Krai, Russia. It is the largest impact event on or near Earth in recorded history, estimated about 1,000 times more powerful than the atomic bomb dropped on Hiroshima, Japan. The Tunguska explosion knocked an estimated 80 million trees down over an area covering 2,150 square kilometres (830 sq mi). It is estimated that the shock wave from the blast would have measured 5.0 on the Richter scale.
Asteroid 2012 DA14 will be closest to Earth on Friday at about 7:24PM GMT (2:24 p.m. EST or 11:24 a.m. PST), when it will be at a distance of about 27,700 kilometers (17,200 miles) above the Earth's surface. This is so close that the asteroid will actually pass inside the ring of geosynchronous satellites, which is located about 35,800 kilometers (22,200 miles) above the equator, but still well above the vast majority of satellites, including the International Space Station. At its closest, the asteroid will be only about 1/13th of the distance to the Moon. The asteroid will fly by our planet quite rapidly, at a speed of about 7.8 kilometers/second (17,400 miles/hour) in a south-to-north direction with respect to the Earth.

Even though 2012 DA14 is coming remarkably close, it will still only appear as a point of light in the biggest of optical telescopes because of its small size.  It will brighten only to magnitude 7.5, too faint to be seen with the naked eye but easily visible in a good set of binoculars or a small telescope. The best viewing location for the closest approach will be Indonesia, from which the asteroid will be seen to move at a rate of almost 1 degree per minute against the star background. Eastern Europe, Asia and Australia are also well situated to see the asteroid around its closest approach.

2012 DA14 has not been in NASA's catalogs for very long -- it was discovered in February 2012 by astronomers at the La Sagra Sky Survey program in southern Spain and reported to the Minor Planet Center. The asteroid had just made a fairly distant passage by the Earth, about 7 times farther than the distance to the Moon when it was first detected by the Spanish group. Since 2012 DA14's orbital period around the Sun has been about 368 days, which is very similar to the Earth's, the asteroid made a series of annual close approaches, this year's being the closest. But this encounter will shorten 2012 DA14's orbital period to about 317 days, changing its orbital class from Apollo to Aten, and its future close approaches will follow a different pattern. The close approach this year is the closest the asteroid will come for at least 3 decades.

This passage of 2012 DA14 by the Earth is a record close approach for a known object of this size. A few other known asteroids have flown by the Earth even closer, but those asteroids were smaller. On average, we expect an object of this size to get this close to the Earth about once every 40 years. An actual Earth collision by an object of this size would be expected much less frequently, about once every 1200 years on average.

The diagram below shows the south-to-north trajectory of 2012 DA14 passing safely above the Earth's surface but well within the ring of geosynchronous satellites.
Click to enlarge.
Astronomy Ireland is hosting a special Asteroid Watch to point some extremely powerful telescopes to the sky to observe the space rock as it passes. This event is free and is ideal for people of all ages and experience. It will take place at 8pm on Friday at the Astronomy Ireland Telescope Shop in Swords, Co Dublin.

"Being able to see an asteroid pass so close to our home planet is probably a once in a lifetime experience, and one that we don't intend to miss!" said David Moore, editor of Astronomy Ireland magazine. "We will have some of the most powerful telescopes in Ireland pointing at the space rock so that people can come along and see it for themselves!"

For further information on asteroid 2012 DA14 and the Asteroid Watch, please visit or call (01) 890 11 11

The extremely close flyby of Earth of a 150-foot asteroid on Friday (Feb. 15) has cast a spotlight on the danger of asteroid impacts to our planet, a threat that an upcoming NASA mission aims to investigate.

Set to launch in 2016, OSIRIS-REx is an unmanned mission to collect samples of the potentially dangerous near-Earth asteroid 1999 RQ36, which is nearly 1,500 feet (457 meters) wide, and return them to Earth. Not only will this effort collect samples of the space rock, but it will also gather the best measurements to date of the small forces that act on asteroids and make them tricky to track.

There are more than 1,300 space rocks that NASA classifies as "potentially hazardous asteroids." These objects measure at least 150 yards (about 140 meters) across and have orbital paths that bring them close to Earth's orbit.

"Asteroids move at an average of 12 to 15 kilometers per second (about 27,000 to 33,000 miles per hour) relative to Earth, so fast that they carry enormous energy by virtue of their velocity," OSIRIS-REx mission deputy principal investigator Edward Beshore of the University of Arizona, Tucson, said in a statement. "Anything over a few hundred yards across that appears to be on a collision course with Earth is very worrisome."