This story was updated at 4:32 p.m. ET.
A tiny asteroid will zip close by Earth tonight (Nov. 16) at a range much closer than the moon, but poses no threat of striking our planet or even entering the atmosphere, NASA has announced.
The asteroid 2010 WA will pass Earth at 10:44 p.m. EST (0344 GMT), missing the planet by about 24,000 miles (38,000 kilometers), NASA's asteroid-watching team wrote on Twitter. It is nearly 10 feet (3 meters wide), so small it would simply break apart if it encountered Earth's atmosphere.
NASA officials said the asteroid is a "very small space rock" that will pass the Earth at roughly one-tenth the distance between our planet and the moon, according to NASA's AsteroidWatch Twitter feed. [ 5 Reasons to Care About Asteroids ]
On average, the moon is about roughly 238,900 miles (384,402 km) from Earth. Some of the highest satellites above Earth fly in geostationary positions about 22,370 miles (36,000 km) up. The International Space Station sails through space about 220 miles (354 km) above Earth.
Asteroid 2010 WA is the fourth space rock in as many months to buzz harmlessly by the Earth within the moon's orbit. The asteroid 2010 TD54 passed the planet at nearly the same miss distance on Oct. 12. In September, a rare sighting of two asteroids called 2010 RX30 and 2010 RF12 was spotted when they both passed within the moon's orbit on the same day (Sept. 8).
Like 2010 WA, those earlier asteroid flybys posed no threat to Earth and most were small enough that they would burn up in the atmosphere if they hit it.
"Still, a good practice in detection," NASA's asteroid-tracking team wrote of 2010 WA on Twitter.
An asteroid about 16.5 feet (5 meters) across can be expected to pass Earth inside the orbit of the moon about once a day, NASA scientists have said. They typically enter Earth's atmosphere about once every two years, they added.
Bigger asteroids of about 460 feet (140 meters) wide can cause widespread damage around their impact sites. But much larger space rocks would have to strike Earth to cause global devastation.
There are an estimated 30 million unknown asteroids in our solar system, NASA has said.
Asteroid 2010 WA is not even the first space rock to slip by the Earth-moon system this month.
On Nov. 9, the small asteroid 2010 VL65 passed the Earth at a range of 610,000 miles (980,000 km) about 2 1/2 times the distance between our planet and moon, NASA officials said. That asteroid was only 23 feet (7 meters) across small enough to burn up completely in the atmosphere and was only visible to seasoned skywatchers with telescopes.
NASA routinely tracks asteroids and comets that fly near Earth as part of its Near-Earth Object Observations program, which uses a network of ground and space telescopes to monitor the space rock environment around the planet. To date, the program has tracked about 85 percent of the largest asteroids that fly near Earth and 15 percent of asteroids in the 460-foot class, according to the latest report.
The U.S. space agency also plans to send astronauts to an asteroid by 2025 under a space plan ordered by President Obama. The mission could help scientists better understand the composition of asteroids, as well as develop better methods of deflecting them before they pose a threat to Earth, agency officials have said.