Warehouse-sized asteroid's surprise weekend near miss

Tuesday, 17 April 2018

A medium-sized asteroid surprised astronomers with an unexpected near miss of the Earth on the weekend.

EarthSky reported the asteroid, labelled 2018 GE3, came within about 192,300 kilometres of Earth at its closest point at 6.41pm on Sunday. That's a little under half the distance between the Earth and the Moon.

The asteroid's diameter was estimated to be between 48 and 110 metres, and it was travelling at 106,497kmh.

Had it entered the atmosphere, a great portion of the asteroid would have broken up, but some might have made it through to the Earth's surface, EarthSky said.

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'An asteroid this big is capable of causing some regional damage, depending on various factors such as composition, speed, entry angle, and location of impact.'

In contrast, the space rock that exploded in an air burst over Chelyabinsk, Russia in February 2013, was about 20m in diameter. According to Nasa, that asteroid generated a shock wave that blew out windows over 500sq km. More than 1600 people were injured in the blast mostly due to broken glass.

The Chelyabinsk asteroid was undetected before it entered the atmosphere.

2018 GE3 was first observed the day before its closest pass, by the Catalina Sky Survey in Arizona, a Nasa-funded project supported by the Near Earth Object Observation Program. The survey's task is to discover and track near-Earth objects.

Space.com said 2018 GE3 was up to 3.6 times the size of the space rock that levelled 2000sq km of Siberian forest when it exploded over Siberia in June 1908.

CNET said 2018 GE3 was among the largest space rocks to come so close to Earth. 'A couple of times a week, on average, an asteroid will come closer than the distance to the Moon, but most of those are hunks about the size of a bus or maybe a house.'