An asteroid as big as an Olympic-sized swimming pool and big enough to flatten London is set to miss Earth tonight - just.
A graphic provided by the University of Hertfordshire roughly charts the asteroid's path and where in the northern sky stargazers will be able to spot Asteroid 2012 DA14.
Experts believe the 45m-wide asteroid will pass our planet from a distance of 17,200 miles.
Because of its trajectory, 2012 DA14 will come within the orbit of more than 100 telecommunication and weather satellites.
Star-gazers will be able to witness the asteroid fly-by from 7.30pm today when it reaches its nearest point to Earth.
With clear skies expected over much of the UK those with powerful binoculars or a telescope will be able to track its progress.
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."
The asteroid is estimated to weigh 130,000 tonnes and will be travelling at more than 28,000 miles per hour - eight times the speed of a rifle bullet - when it passes over our planet.
Astronomer and asteroid expert Dr Dan Brown, from Nottingham Trent University, said: "There are loads of them but you're talking about a very big area. It would be very unlucky if a satellite was hit. The asteroid is more likely to hit some space junk, but most of this is only about a centimetre across and the impact won't even be noticed."
The asteroid follows a dramatic meteor event in Russia where 400 people were injured - however the two are unrelated.
Precise calculations show there is absolutely no possibility of DA14 hitting the Earth.
But scientists have a good idea of what the effect of such an impact would be as a similar-sized meteor struck a remote region of Siberia in 1908, devastating the area.
The asteroid exploded above ground over Tunguska which generated a blast 1,000 times more powerful than the atom bomb dropped on Hiroshima in the Second World War. Vast stretches of remote forest were flattened by the force of the blast.
The fly-by will provide a unique opportunity for scientists to study asteroids. Radar will be used to learn about its composition and structure which would be useful in case a space rock did pose a real danger to Earth.