An asteroid about half the size of a football field will hurtle past Earth on February 15, NASA scientists report.
While there is no chance the flying rock will collide with our planet, it will break the record for the closest fly-by of an asteroid its size.
"Since regular sky surveys began in the 1990s we've never seen an object this big get so close to Earth," said Don Yeomans, a planetary scientist with NASA's Near Earth Object Program at the Jet Propulsion Laboratory.
The 50-metre wide asteroid, known as 2012 DA14, will come within 28,000 kilometres of Earth's surface, closer than the belt of geosynchronous satellites that record weather data and telecommunications.
As the asteroid approaches NASA's Goldstone radar in the Mojave Desert will track its path, collecting data on its size, spin and shape.
At its closest point it will be bright enough to see with a basic telescope, but the speed it will travel will make it difficult to follow.
"The asteroid will be racing across the sky, moving almost a full degree every minute," said Dr Yeomans.
Scientists suspect the asteroid is made of stone, rather than metal or ice.
Dr Yeoman said an asteroid the size of 2012 DA14 impacts Earth about once every 1200 years.
"[But it] will definitely not hit Earth," said Dr Yeoman.
"The orbit of the asteroid is known well enough to rule out an impact," he said.
A similar-sized asteroid that collided with Earth about 50,000 years ago created the 1.6-kilometre wide Meteor Crater in Arizona.
Earth is surrounded by asteroids of varying sizes, many of which originate from the asteroid belt, located between Mars and Jupiter.
To date, NASA's Near Earth Object Program has tracked 9562 near-Earth asteroids.
Scientists have tracked the orbit of most large asteroids, those that measure many kilometres in diameter.
