Sky watchers will have the chance to see an asteroid big enough to destroy London narrowly miss the Earth on Friday.
Scientists are sure there is no chance of the 150ft-wide space rock hitting the planet. But it could come as close as 17,200 miles - placing it within the orbits of more than 100 telecommunication and weather satellites.
The asteroid, 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 UK time on Friday. Given clear skies, it should be possible to track the rock climbing in the north-eastern sky from anywhere in the UK.
DA14 will take two hours to travel between the constellations of Leo and the Plough from 8pm.
Robin Scagell, vice-president of the Society for Popular Astronomy, said: "It will be possible to see it if you know where to look, but just waving your binoculars in the right general direction isn't going to work.
"The asteroid will be a faint dot of light moving at a steady rate between the stars. It'll be thousands of times fainter than Jupiter and 250 times fainter than the stars of the Plough.
"The trick will be to find the area in advance and wait for it to come through. You can use the star maps to find exactly the right part of the sky. If you hold your binoculars steady you will see this tiny point of light crawling across your field of view in about seven or eight minutes. It's not easy, but you will have the thrill of knowing you are seeing a little object in space the size of an office block."
DA14 will climb steeply from a point just below Leo, growing fainter as it travels across the sky. At the point it reaches the handle of the Plough, it will be 35 degrees above the horizon - equivalent to three stacked fists an arm's length away.
DA14 belongs to a dangerous family of near-Earth objects that are small enough to be missed but large enough to cause serious damage. It was detected in February last year by La Sagra Observatory in southern Spain as it fell under the spotlight of the Sun's rays.