The asteroid, between one-third of a mile and two-thirds of a mile wide, will pass within 1.3 lunar distances -- based on the 240,000-mile average separation of the moon's orbit from Earth. This is very close by astronomical standards, said Tim Spahr, an astronomer and near-Earth asteroid, or NEAR, specialist for the Minor Planet Center at the Smithsonian Astrophysical Observatory in Cambridge, Mass.
Asteroid 2002 NY40 was discovered July 14 by the Massachusetts Institute of Technology's Lincoln Near Earth Asteroid Research project, according to Roger Sudbury, its executive officer. Sudbury told United Press International that LINEAR, which is the major discoverer of new asteroids, began to track 2002 NY40's near-Earth encounters about two years ago.
Spahr told UPI there currently are "a few hundred thousand asteroids that we track right now, and a couple of thousand near-Earth asteroids." An asteroid is considered to be "near Earth" when it is capable of approaching within 0.3 astronomical units of our planet. One AU equals the distance between the Earth and the sun. "That's not particularly close," Spahr said. Objects within 0.05 AU of Earth -- such as 2002 NY40 -- are categorized as "potentially hazardous." The asteroid is so categorized even though there is no chance it will hit Earth during the foreseeable future.
Spahr said objects this size pass reasonably close to Earth a few times each year. There has been some media coverage recently of another asteroid -- 2002 NT7 -- a planetoid over one mile wide that will pass near Earth on Feb. 1, 2019. At present, astronomers estimate there is less than a one-in-250,000 chance it will hit the planet. The most well-known planetary impact event is the large asteroid that hit Earth about 65 million years ago, which is considered responsible for a mass extinction that wiped out the dinosaurs.
Asteroid 2002 NY40 is described as fairly typical. Its Aug. 18 pass by will allow scientists to study it with relatively unsophisticated equipment from Earth.
Don Yeomans, manager of NASA's Near-Earth Object Program Office in Pasadena, Calif., also emphasized there is no chance the asteroid will collide with Earth. However, he told UPI, "When an object that gets that close, it gets very bright and allows telescopes of all sizes to study it. It's really an opportunity for ground-based equipment to get high signal-to-noise data on an asteroid."
Asteroids are pieces left over from the formation of solar system, Yeomans said. "If you want to study the mix from which the planets are made, you want to study the asteroids, which have changed very little."
In addition, objects that pass near Earth become potential targets for future spacecraft missions, he said. If mankind begins to colonize the nearby planets, asteroids can become a source of water and metals, perhaps the raw materials for space colonization.
One team of observers at the giant Arecibo radiotelescope in Puerto Rico will "ping" 2002 NY40 with radio waves as it approaches Earth. That effort may be able to resolve a picture of the object, Yeomans said, as well as find out what it is made of.
(Reported by Dan Whipple, UPI Science News, in Broomfield, Colo.)