This story was updated at 4:32 p.m. ET.
A tiny asteroid will zip close by Earth tonight (Nov. 16) at arange much closer than the moon, but poses no threat of striking our planet oreven 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-watchingteam wrote on Twitter. It is nearly 10 feet (3 meters wide), so smallit would simply break apart if it encountered Earth's atmosphere.
NASA officials said the asteroid is a "very small spacerock" that will pass the Earth at roughly one-tenth the distance betweenour planet and the moon, according to NASA's AsteroidWatch Twitter feed. [5 Reasons to CareAbout Asteroids]
On average, the moon is about roughly 238,900 miles (384,402 km) from Earth. Some of the highest satellites above Earth fly ingeostationary positions about 22,370 miles (36,000 km) up. The InternationalSpace Station sails through space about 220 miles (354 km) above Earth.
Asteroid 2010 WA is the fourth space rock in as many months tobuzz harmlessly by the Earth within the moon's orbit. The asteroid 2010 TD54 passedthe planet at nearly the same miss distance on Oct. 12. In September, a rare sighting of twoasteroids ? called 2010RX30 and 2010 RF12 ? was spotted when they bothpassed within the moon's orbit on the same day (Sept. 8).
Like 2010 WA, those earlier asteroid flybys posed no threat toEarth and most were small enough that they would burn up in the atmosphere ifthey hit it.
"Still,a good practice in detection," NASA's asteroid-tracking team wrote of 2010 WA onTwitter.
Anasteroid about 16.5 feet (5 meters) across can be expected to pass Earth insidethe orbit of the moon about once a day, NASA scientists have said. Theytypically enter Earth's atmosphere about once every two years, they added.
Biggerasteroids of about 460 feet (140 meters) wide can cause widespread damagearound their impact sites. But much larger space rocks would have to strikeEarth to cause global devastation.
Thereare an estimated 30 million unknown asteroids in our solar system, NASA hassaid.
Asteroid 2010 WA is not even the first space rock to slip by theEarth-moon system this month.
On Nov. 9, the small asteroid 2010 VL65 passed the Earth at arange of 610,000 miles (980,000 km) ? about 2 1/2 times the distance betweenour planet and moon, NASA officials said. That asteroid was only 23 feet (7meters) across ? small enough to burn up completely in the atmosphere ? and wasonly visible to seasoned skywatchers withtelescopes.
NASAroutinely tracks asteroids and comets that fly near Earth as part of itsNear-Earth Object Observations program, which uses a network of ground andspace telescopes to monitor the space rock environment around the planet. Todate, the program has tracked about 85 percent of the largest asteroids thatfly near Earth and 15 percent of asteroids in the 460-foot class, according tothe latest report.
TheU.S. space agency also plans to send astronauts to an asteroid by 2025 under aspace plan ordered by President Obama. The mission could help scientists betterunderstand the composition of asteroids, as well as develop better methods ofdeflecting them before they pose a threat to Earth, agency officials have said.
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