The space rock had been invisible to astronomers until January 5, but scientists quickly calculated the asteroid, named 2018 AJ, will fly past Earth Tuesday, January 23.
But NASA admits it is not yet certain of its orbital path.
New asteroids are given a condition code of between 0 to 9 based on how certain astronomers are about its course.
Zero means they are fairly certain, but 9 is classed as "highly uncertain".
It is currently believed it will pass at a comfortable 4.6 times the distance from Earth to the Moon.
GettyAsteroid 2018 AJ was discovered on January 5 and passes next Tuesday.Related articles
Last year, we discovered 1,985 new near Earth asteroids. There were 1888 such objects discovered in 2016 and 1,571 in 2015.
The Moon is 238,000 miles from Earth and this pass, currently estimated at around 1.1 million miles, is considered a cat’s whisker in astronomical terms.
NASA considers and monitors anything which comes within six million miles of our planet as a near earth asteroid.
The asteroid is estimated to be between 22 and 68 metres in diameter, meaning it is bigger than a three-storey house.
If something of that size did impact Earth, it could decimate a whole city.
In February 2013, an unknown 19-metre meteor came from nowhere to explode in the sky above Chelyabinsk, Russia, with the force of 500,000 tonnes of TNT.
And the energy released shattered glass on hundreds of buildings and more than 1,000 people were injured as a result.