An asteroid the size of a small house passed extremely close to the Earth early Thursday, according to the U.S. space agency.
Astronomers stressed the space rock, 2012 TC4, was never expected to hit the planet, although it did come very close, astronomically speaking.
At 0542 GMT, it zipped just 42,000 kilometers (26,097 miles) above Antarctica. The moon is about 385,000 kilometers (239,227 miles) above the Earth.
As its name suggests, the asteroid was first spotted in 2012 by a telescope in Hawaii. Astronomers lost sight of it for several years before observing it again in July, which is also when they calculated it would fly near the Earth's southern edge.
"Scientists have always appreciated knowing when an asteroid will make a close approach to and safely pass the Earth because they can make preparations to collect data to characterize and learn as much as possible about it," Michael Kelley, a NASA scientist leading the campaign to observe the asteroid, said in a statement.
"This time we are adding in another layer of effort, using this asteroid flyby to test the worldwide asteroid detection and tracking network, assessing our capability to work together in response to finding a potential real asteroid threat."
NASA estimated 2012 TC4 measures between 10 and 15 meters (33 and 50 feet) in diameter. Even if it smashed into Earth's atmosphere, scientists were not too concerned about major damage.
NASA said an impact likely would have resulted in a massive fireball as the rock burned up in the sky.
NASA noted no asteroid is scheduled to hit the Earth for the next 100 years.
Less than a day later, the asteroid is already on a journey away from Earth. About 14 hours after it passed by Earth, it passed the moon at a distance of about 277,000 kilometers (172,000 miles).
