NASA astronomers identified what they say is the 10,000th near-Earth object seen flying through space. (Photo : PS-1/UH / NASA )

NASA astronomers identified what they say is the 10,000th near-Earth object seen flying through space.

Near-Earth objects include asteroids or comets that can approach the Earth's orbital distance to within about 28 million miles (45 million km). The largest known near-Earth object is the asteroid 1036 Ganymed, which is 25 miles (41 km) across, while smaller near-Earth objects have been measured at just a few feet across.

"Finding 10,000 near-Earth objects is a significant milestone," Lindley Johnson, program executive for NASA's Near-Earth Object Observations Program, said in a statement. "But there are at least 10 times that many more to be found before we can be assured we will have found any and all that could impact and do significant harm to the citizens of Earth."

Lucky number 10,000 is the asteroid 2013 MZ5, which was first detected on the night of June 18. The asteroid is about 1,000 feet across (300 meters) and its orbit is well-enough understood that NASA reports it will not approach close enough to become potentially hazardous.

In the past 10 years, more than three-quarters of near-Earth object discoveries have been made, NASA reported.

"The first near-Earth object was discovered in 1898," said Don Yeomans, long-time manager of NASA's Near-Earth Object Program Office at the Jet Propulsion Laboratory. "Over the next hundred years, only about 500 had been found."

But Yeomans said, the advent of the Near-Earth Object Observation Program in 1998 tipped the scales.

"We've been racking them up ever since," Yeomans said, adding that as more advanced detection systems come into play researchers will gain a much clearer understanding of where the near-Earth objects are and where they are going.

Of the 10,000 near-Earth objects identified, about one-tenth of them are larger than one kilometer (six-tenths of a mile) in size

To cause significant devastation in populated areas on Earth, an asteroid would only need to be 100 feet across, NASA reports. While most of the very large near-Earth objects are believed to be accounted for, only about one percent of the objects in the 100-foot-across category have been detected, NASA said.

The current near-Earth object discovery rate is about 1,000 per year.

Still, the work of NASA alone may not be enough to detect all possible threats to Earth. The Obama administration and NASA are preparing to ask the public to step in and help find potentially Earth-damaging asteroids.

"This is really a call to action to find all asteroid threats to human populations and know what to do about them," NASA Deputy Administrator Lori Garver said last week. The Guardian reported that Garver added that the asteroid hunt would help prove that "we're smarter than the dinosaurs".