They were studying asteroid 1950 DA, which has a one in 300 chance of hitting the planet on 16 March, 2880.

Although the odds seem small, it is the most likely asteroid to collide with Earth and the odds are higher than being shot dead in the US.

The asteroid has a diameter of one kilometre and is travelling at nine miles a second relative to the Earth, which it would hit at 38,000 miles per hour.