Powerful asteroids hitting the Earth's atmosphere caused 26 nuclear-scale explosions between 2000 and 2013, including one that was much stronger than the atom bomb that destroyed Hiroshima, a report has found.
The findings came from the Nuclear Test Ban Treaty Organisation, a global infrasound network that detects nuclear weapon detonations and recorded the impacts over 13 years.
Most explosions occurred too high in the atmosphere to cause any serious damage on Earth but "the only thing preventing a catastrophe from a ‘city-killer’-sized asteroid has been blind luck," said former astronaut Ed Lu as he revealed the data at the Museum of Flight in Seattle today, NBC reported.
Mr Lu added that while large asteroids have been detected, "less than 10,000 of the more than a million dangerous asteroids with the potential to destroy an entire major metropolitan area have been found."
It may not look like much, but this is the asteroid big enough to flatten London that narrowly missed the Earth tonight. The 150ft-wide space rock came as as close as 17,200 miles to Earth's surface.
The asteroid, given the name of 2012 DA14, has been closely tracked since its discovery by a Spanish observatory a year ago.
You can watch live images from the Bayfordbury AllSky Camera here. Hover over the image for information on what you're seeing.
Despite cloudy skies, scientists at the Bayfordbury Observatory at the University of Hertfordshire are still hoping to get a glimpse of the asteroid in the next 90 minutes.
The asteroid, given the not so catchy name of 2012 DA14, has been closely tracked since its discovery by a Spanish observatory a year ago. It is predicted to reach its nearest point to Earth at around 7.30pm tonight UK time.
Sky watchers have been told that given clear skies they should be able to track the rock climbing in the north-eastern sky from anywhere in the UK.
An asteroid called 2012 DA14 will narrowly miss Earth as it flies past at 7pm tonight.
The 45 metre diameter rock is big enough to destroy London.
It has no chance of hitting, but it will enter the orbit of more than 100 satellites.
It is expected to fly 17,200 miles (27,000 kilometres) above Earth's surface at around 7pm GMT.
The flyby of 2012 DA14 is the closest-ever predicted approach to Earth for an object this large.