An asteroid discovered last year could hit the Earth on 5 February 2040, says NASA - but really probably won't.
Asteroid 2011 AG5 - nicknamed Apophis - registers as 1 on the Torino scale, meaning it 'merits careful monitoring'. It's 460 feet across, and is much smaller than the asteroid believed to have wiped out the dinosaurs, but could still make quite a mess if it hit.
However, scientists say there's very little chance of an impact - and the odds are likely to improve as more data's gathered on its orbit.
Because of its current location in the daytime sky, Earth-based telescopes haven't yet been able to determine its orbit accurately.
However, 2011 AG5 will be close enough for a better look well before 2040.
It'll next be near Earth in February of 2023, when it will pass no closer than about 1.2 million miles. It'll be back again in 2028, but a lot further away, at around 12.8 million miles.
According to NASA's Near-Earth Object Program Office, it's possible that when these flybys take place, the Earth's gravitational influence could put it on an impact course for February 2040. It's highly unlikely, though, with odds of just one in 625 - and falling.
"In September 2013, we have the opportunity to make additional observations of 2011 AG5 when it comes within 91 million miles of Earth," says Don Yeomans, manager of NASA's Near-Earth Object Program Office at the Jet Propulsion Laboratory.
"It will be an opportunity to observe this space rock and further refine its orbit. Because of the extreme rarity of an impact by a near-Earth asteroid of this size, I fully expect we will be able to significantly reduce or rule out entirely any impact probability for the foreseeable future."
2011 AG5 is one of 8,744 near-Earth objects to have been found, and was discovered on January 8, 2011, by astronomers using a 60-inch Cassegrain reflector telescope at the summit of Mount Lemmon in Arizona.