Earth just narrowly escaped an impact by one of the closest large asteroids on record.* The space rock, which was up to 110 meters wide, shot by at half the distance of the Moon yesterday, April 15th. 

Astronomers only detected the incoming asteroid a day earlier thanks to an early-warning system monitoring the skies from mountains near Tucson, Arizona.

Experts say the asteroid, labelled 2018 GE3, came as close as 192,200 km (119,400 miles) before heading off into outer space again. If it had hit a populated area of Earth, it would have caused regional devastation.

The asteroid was discovered by the Catalina Sky Survey, which constantly watches the sky with telescopes for NASA to find threatening asteroids.

From its brightness, astronomers estimate it to have been between 48 meters and 110 meters wide (160ft to 360 ft). It is one of the Apollo class of asteroids, and on an orbit that carries it from beyond Mars to within the orbit of the closest planet to the Sun, Mercury.

A similar asteroid or comet exploded above Tunguska, a remote forested part of Siberia, in 1908, flattening trees for an area 2,000 square km (800 sq miles) in size. That blast is estimated to have been equivalent to around 15 million tons of TNT.

In February, 2013, a smaller meteor, more than 17 meters (55 ft) wide, exploded as a daylight fireball over the Russian city of Chelyabinsk, shattering windows and injuring about 1,000 people.

Asteroid 2018 GE3 is one of the largest known asteroids in recorded times to pass so close to the Earth or the Moon. But in April 2029, a larger asteroid called Apophis will pass by at a distance of just 33,000 km (20,000 miles).

* Though 2018 GE3 was initially announced as the largest recorded close approach, the ever vigilant Daniel Fischer has pointed out (in German) that a closer-passing asteroid in 2002 (2002 MN) may have been larger. It had a similar brightness but came to within 122,670 km (76,225 miles). This story has been updated to reflect this.

NASA video about the meteor strike.Credit: NASA