Anxious Earthlings need not worry too much for another 24 years, however, because asteroid 2004 MN4 is not due to make its closest approach to Earth until about 10pm London time on Friday 13 April 2029.

The latest calculations of the rock's orbit suggest that it will come so close that it will probably be visible to the naked eye from Britain. It will shine in the sky as a dim, fast-moving star - the first asteroid in modern times to be clearly visible from Earth without the aid of a telescope or binoculars.