WASHINGTON – An asteroid nearly 3 km wide has passed by Earth, offering scientists a rare chance to study a massive flying object with its own moon.
U.S. space agency NASA said ahead of the event that Asteroid 1998 QE2 was to come closest to Earth at 20:59 Greenwich Mean Time on Friday (5:59 a.m. Saturday in Japan), at a distance of 5.8 million km, or about 15 times the distance between Earth and the moon.
“This is the closest approach the asteroid will make to Earth for at least the next two centuries,” NASA said.
The asteroid was not visible to the naked eye, but radar astronomers were studying it with complementary imaging telescopes in California and Puerto Rico and will continue to analyze it until June 9.
On Thursday, NASA scientists using the 70-meter Deep Space Network antenna at Goldstone, California, reported that the asteroid, first discovered in 1998, also appears to have its own moon.
The huge flying object is known as a binary asteroid, and is circled by a satellite, or moon, that is about 600 meters wide, NASA said.
Scientists hoped that measurements gathered as the asteroid approached and passed would help space agencies track other asteroids, including those that might impact the Earth, and calculate their orbits further in advance.
“Radar measurements of asteroid distances and velocities often enable computation of asteroid orbits much further into the future than if radar observations weren’t available,” NASA said.
The asteroid-moon duo is in rare company — NASA says about 16 percent of asteroids that are 200 meters or larger are binary or triple systems.