spaceSpace and Physics

A House-Sized Asteroid Just Narrowly Missed Earth - But It's Coming Back, And May Not Miss Next Time


Jonathan O'Callaghan

Senior Staff Writer

Artist's impression of 2012 TC4. NASA

An asteroid flew past Earth the other day, and there is a small but not insignificant chance it will hit us when it returns in 2079.

Called 2012 TC4, the asteroid flew about 42,000 kilometers (26,000 miles) above Antarctica early Thursday, October 12, about a tenth the distance between Earth and the Moon.


Studies during this flyby should nail down the size of this asteroid a bit more. We know it’s about 15 to 30 meters (45 to 100 feet) across, roughly the size of a house. That’s about the same size as the asteroid that exploded above Chelyabinsk in Russia in February 2013.

It takes 609 days for 2012 TC4 to orbit the Sun, but owing to the particulars of its and our orbit we will not see it again until 2050, and then 2079. The risk of an impact this time around was essentially nothing, but in 2079 it is one in 750 – or 0.13 percent.

“We know today that it will also not hit the Earth in the year 2050, but the close flyby in 2050 might deflect the asteroid such that it could hit the Earth in the year 2079,” Rüdiger Jehn of the European Space Agency’s Near-Earth Object program told AFP.

That probability is still very small. Even if it did hit Earth, the effects would be minuscule. Paul Chodas from NASA’s Center for Near Earth Object Studies told it “would be simply a flash through the atmosphere and a breakup – a very bright fireball, basically.”


A short movie of asteroid 2012 TC4 taken by the Kiso Schmidt telescope in Nagano, Japan.

So, thankfully, there’s probably not too much to worry about. But this asteroid is interesting because scientists have been using it as a trial run to prepare for a future cataclysmic asteroid impact, which could end life on Earth.

"This campaign is a team effort that involves more than a dozen observatories, universities, and labs around the globe so we can collectively learn the strengths and limitations of our near-Earth object observation capabilities," Vishnu Reddy from the University of Arizona, who led the project to study the asteroid, said in a statement.

Currently, there is no risk of a devastating impact. Perhaps the biggest threat is 2009 FD, an asteroid 160 meters (535 feet) across that has a one in 630 chance of hitting Earth between 2185 and 2198.


On NASA’s list of potential impacts, 2012 TC4 ranks only 13th. And its small size is such that we really wouldn’t have much to worry about.

But an asteroid wiped out the dinosaurs, and the chances are we might one day be faced with a similar threat. Making sure we can track asteroids, and even prepare what we would do if one was heading our way, is hugely important.


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