Earth's close shave with an asteroid
In Summary
The Earth had a ‘close shave’ this morning when an 8,300 ton asteroid flew over New Zealand and Australia, coming nearly as close as our weather and communication satellites (~40,000km) at 4.18am AEST and reaching speeds of 10km per second.
The object, asteroid 2014RC, was only discovered on 31 August by the Catalina Sky Survey and confirmed by Hawaiian telescope Pan-STARRS. NASA announced the predicted, safe, trajectory just days later.
A similarly sized object hit Russia last year in Chelyabinsk, and exploded with a force 20-40 times that of the Hiroshima atomic blast, sending shockwaves across the region and injuring thousands.
“While NASA believes it has found over 90 per cent of the dinosaur-killing sized asteroids of 1km and larger, these smaller 'city'-killers are far harder to find and we've seen only a few thousand of the expected 1 million objects that pass the Earth,” Swinburne University of Technology astronomer Dr Alan Duffy said.
“On average we find a new asteroid each month, so there's a long way to go.”
Asteroids are often coal black in appearance, reflecting little light to any watching telescope.
“Together with a bright 'Supermoon' that outshone the asteroid 2014RC by a billion times, it was a disappointing morning for amateur astronomers,” Dr Duffy said.
“Radio astronomers had more luck as they used the giant Goldstone radio telescope to bounce radio waves off the asteroid – like a bat's echo location – finding that 2014RC was rotating every 20 seconds making it the fastest 'tumbling' asteroid yet seen.”
Dr Duffy said asteroids like 2014RC hit the Earth’s surface once every 20-30 years.
“As Chelyabinsk was hit by just such an object last year I wouldn't expect something that big again until the 2030s.”
** An earlier version of this article stated that the estimated weight was 70,000 tonnes, based on misreading the initial NASA 'width' estimate as radius not diameter.
Watch Dr Duffy on ABC News Breakfast describing the asteroid that made a close but safe journey past Earth here.
For more information follow @astroduff on Twitter.