Enormous, Potentially Hazardous Asteroid Just Passed Earth, NASA Says

An asteroid potentially 2,560 feet in diameter flew past Earth late on Wednesday night whilst travelling at more than 23,000 miles per hour, NASA data shows.

The space rock, called 418135 (2008 AG33) came closest to Earth at about 10:46 p.m. ET on Wednesday night (2:46 a.m. UTC on Thursday).

NASA's Center for Near Earth Object Studies (CNEOS) described the encounter as a "close approach" but thankfully the asteroid did not pose any risk to Earth. Even at its closest, the asteroid was 2 million miles away from us—more than eight times the average distance between the Earth and the moon.

Still, this is relatively close in cosmic terms. Indeed, 2008 AG33 is classed as a potentially hazardous asteroid (PHA) due in part to its size—it's estimated to be between 1,150 feet and 2,560 feet in diameter, meaning it is about two times as wide as the Empire State Building is tall.

A stock illustration depicts an asteroid in space against a backdrop of stars. Scientists keep track of thousands of space rocks so they can predict when they will come near Earth. vencavolrab/Getty

Another reason for its PHA classification is because of the asteroid's potential to make threatening close passes to Earth as it orbits the sun, though it may never actually hit us.

According to orbital predictions, 2008 AG33 is not expected to come as close to Earth again as it did this week until 2059. Even then, it should be a safe distance away.

Scientists keep track of many thousands of asteroids, enabling them to make predictions as to when they will come close to Earth and whether we should be concerned.

The possibility of a significant asteroid impact may sound like science fiction, but it's something that experts are seriously planning for.

Defending Earth from an asteroid impact is the basis of NASA's Double Asteroid Redirection Test (DART) mission that was launched in November last year and is expected to demonstrate technology capable of changing the path of an asteroid through space. Scientists have previously told Newsweek about the different ways in which an impending asteroid impact would be tackled, including the use of a nuclear bomb.

Despite scientists' best efforts some space rocks slip past undetected. In February, 2013, a space rock entered the atmosphere and exploded in the sky over the city of Chelyabinsk in Russia. The rock, described as "house-sized" by NASA, released energy equivalent to 440,000 tons of TNT and blew out windows over 200 square miles. Over 1,600 people were injured, mostly due to broken glass, the space agency said.

According to CNEOS, an asteroid larger than about 100 meters or 328 feet would be expected to reach Earth's surface once every 10,000 years or so on average, causing local disasters or tidal waves.

Much smaller interplanetary particles like motes of dust encounter Earth much more regularly with about 100 tons of it drifting down to Earth's surface every day, CNEOS states.