The asteroid, 2012 DA14, was discovered by Spanish astronomers in February 2012, when it made a pass much farther away, coming 1.6 million miles away from Earth at its closest. This year, the asteroid will be coming within 17,200 miles of Earth's surface on Friday, still well away from Earth's atmosphere and a distance more than twice the diameter of our planet.
“NASA's Near-Earth Object Program Office can accurately predict the asteroid's path with the observations obtained, and it is, therefore, known that there is no chance that the asteroid might be on a collision course with Earth,” the space agency said in a statement. “Nevertheless, the flyby will provide a unique opportunity for researchers to study a near-Earth object up close.”
The space agency will be employing its Goldstone Solar System Radar, located out in California's Mojave Desert, to take radar images of 2012 DA14 as it flies overhead. Other observatories across the globe will be watching as well to better determine the asteroid's spin rate and composition.
“If radar observations of this asteroid are successful, we might have a more accurate estimate of the asteroid’s size after its close approach,” NASA said.
Scientists at NASA estimate that an asteroid the size of 2012 DA14 flies this close to Earth about once every 40 years. A 2012 DA14-size asteroid impacts Earth once every 1,200 years, on average.
If 2012 DA14 were to smash into Earth, it would be regionally devastating but not necessarily civilization-ending, according to NASA. Such an impact would release about 2.5 megatons of energy into the atmosphere -- equivalent to more than 1,000 times the energy released by the Fat Man nuclear bomb dropped on Nagasaki in World War II. Though that number is impressive, it's easily dwarfed by the most powerful man-made bomb ever detonated, the 57-megaton Tsar Bomba, as well as the 100,000,000-megaton force of the asteroid impact blamed for the extinction of the dinosaurs.
In 1908, an asteroid a little big smaller than 2012 DA14 flattened about 750 square miles of forest in Siberia in the Tunguska event, the largest impact event on record.
Despite 2012 DA14's close approach, it'll still be invisible to the naked eye. But people in Europe, Africa and Asia should be able to catch a glimpse of the asteroid at its closest through a telescope. In the U.S., starwatchers with telescopes should be able to see the asteroid best around sunset, just after the closest approach.
While 2012 DA14's pass won't affect Earth in a very meaningful way, we'll have a much bigger influence on it, reducing its orbital period around the sun from 366 days to 317 days, according to astronomer Phil Plait.
Current observations peg the chances of 2012 DA14 impacting Earth in February 2080 at 1 in 385,000. Though with the measurements taken during this latest flyby, that could change.
Earth had another close shave in January. The asteroid Apophis, a much heftier space rock at more than 1,000 feet across, passed within 22,300 miles of Earth. Apophis is scheduled to make even closer flybys in 2029 and 2036, but the measurements taken last month have ruled out an impact in both those years.