Near-miss as asteroid grazes Earth
A HIGHRISE-sized asteroid slipped quietly past the Earth yesterday, twice as close as the Moon. We didn't see it coming.
Now designated 2017 AG13, the 10-storey (25-35m) tall space rock was first spotted late on Sunday by the Catalina Sky Survey. It was travelling at 16 kilometres every second.
"This is moving very quickly, very nearby to us," an expert with astronomy news website Slooh, Eric Feldman, said during a hastily arranged live broadcast of the fly-by yesterday.
asteroid (2017 AG13) missed earth by 0.5 lunar distances: diameter ~25 m, velocity 15.7 km/s, energy ~723 kilotons. https://t.co/NVeUEeiMfL— Asteroids and Comets (@AsteroidMisses) January 9, 2017
He said the asteroid was roughly the same size as that which exploded in the sky above Chelyabinsk, Russia, in 2013. This blast shattered windows and caused minor damage to buildings over a wide area. More than a thousand people were reportedly injured by flying glass and debris.
Its orbit will also take it through the path of Venus, he said.
While you were hitting snooze, we nearly hit an asteroid! At 7:47 AM EST an asteroid we only first spotted Saturday gave us a wake up call. pic.twitter.com/BbAQc7e2EJ— Slooh (@Slooh) January 9, 2017
The asteroid was roughly half the size designed to be detected by NEOCam, an infra-red telescope surveying the sky for potentially damaging asteroids that have orbits intersecting with Earths.
The program last week only received only partial funding from NASA to continue its search.
Last month, the US White House released a document outlining a Near-Earth Object Preparedness Strategy.
The policy document seeks to "improve our nation's preparedness to address the hazard of near-Earth object (NEO) impacts by enhancing the integration of existing national and international assets and adding important capabilities that are currently lacking."
In the case of 2017 AG13, the asteroid would likely have exploded high in the atmosphere with the force of 700 kilotons. The Nagasaki bomb was 20 kilotons.
Early warning remains an issue, the document admits.
Asteroids vary in size, brightness and orbit - making many of them difficult to identify and track.
They can range from a few meters to several kilometres across. Some are made of ice. Others rubble. Some can be almost pure metal.
The Planetary Society believes only 60 per cent of near-Earth objects bigger than 1.5km have so far been spotted.
The number of smaller objects is many times this.
But the chances of a "potentially hazardous" asteroid impact on Earth in the next 100 years is just 0.01 per cent, the White House document says.
Roughly five new asteroids are being discovered every day.