Are we about to get smacked in the face by near-Earth asteroid TC4, due to pass between our planet and the moon in October?
For at least two years, online sky-watchers and respected science blogs have asked if the bus-sized asteroid’s visit will be a calamitous one.
Anxieties ramped up again in January when a previously unknown asteroid 2017 BH30, said to be the size of a small truck, passed within 51,800 kilometres of Earth. Northern hemisphere asteroid watchers standing sentinel only spotted BH30 the day before it whizzed by.
At least they had some warning on that occasion.
According to Glen Nagle, NASA Operations Support Officer at the Canberra Deep Space Communication Complex, the asteroid that exploded over the Russian city of Chelyabinsk in February 2013, injuring 1500 people and blowing countless windows out of buildings, was unknown to astronomers until it went boom.
“Nobody saw it coming,” Mr Nagle told The New Daily. Asteroid watchers were preoccupied with another object on that occasion he said.
And now all eyes are on TC4.
Five days ago, The Christian Post headlined: “Possible asteroid strike predicted to happen on October 12.”
It’s been widely reported that TC4 will cross Earth’s orbit at 0.15 lunar distances – or just 57,659 kilometres away. In 2012, it crossed harmlessly at about 59,000 kilometres.
But Glen Nagle said NASA’s Near Earth Object website has posted that TC4 will pass Earth at a minimum of 94943.57 km.
“I’ve seen other references which note that it will be .15 lunar distances from Earth,’’ he said. “I think that the discrepancy may come from the degree of uncertainty about its orbital parameters.”
He noted that in the grand canvas of space, these distances are tiny. But in terms of being a risk to Earth? “There isn’t any.”
2012 tc4 asteroid. ….Shaved Earth on its last pass .Coming around again in October 2017 …… pic.twitter.com/oviq9uxjnx
— Notaplebian (@ALMALIKISBACK) February 2, 2017
TC4 is one of five asteroids to make a close call on Earth between July and the end of the year. All of them will come within four lunar distances of our backyard – that is, four times the distance of Earth to the moon. Some reports have claimed that NASA is nervous. Mr Nagle denied this is the case.
However, he pointed out that the number of professional astronomers tracking asteroids – and looking for new ones – at any one time “would be less than the number of people employed by your average McDonalds outlet.”
And just about all of them are in the northern hemisphere. Australia had its own asteroid program, but the funding, $200,000, was cut in 1996. There is no professional body tracking asteroids in the southern hemisphere – standing guard on half the earth is left to a handful of amateurs – dedicated, but lacking the sort of technology needed for the job.
An asteroid the size of TC4 might hurt a thousand people or so, depending on where it exploded in the atmosphere. It would take an object at least a kilometre long to wipe out life on earth, or a good part of it.
The trick, of course, is to see it coming.