The chunk of space rock - dubbed 2012 LZ1 - is up to 700metres wide and is scheduled to pass our planet shortly after midnight (GMT).
It will be 3.35million miles away, roughly 14 times the distance between Earth and the moon.
A giant asteroid that astronomers have compared to the size of a city block is due to fly past Earth in the early hours of tomorrow morning.
Fly-by: A giant asteroid that astronomers have compared to the size of a city block is due to hurtle past Earth at midnight (GMT)
While there is no danger of a collision, this is still close enough for it to be filmed.
But as it is less than 4.65million miles away and more than 150metres wide, the asteroid is classified as potentially hazardous.
It was spotted three days ago by astronomer Rob McNaught when he was looking through the Uppsala Schmidt telescope at Siding Spring Observatory in Australia.
Two weeks ago, a 16ft-wide asteroid narrowly missed Earth by a mere 8,900 miles when it hurtled past our mortal coil at 38,000 miles per hour.
At its closest, that fly-by was about the same distance as a flight from New York City to New Zealand.
Scientists weren't worried, though. Asteroid 2012 KT42, as astronomers dubbed it, likely would have burned up in the planet's atmosphere before ever getting a chance to wreak havoc on the surface.
But Nasa's Jet Propulsion Laboratory said the asteroid was the 6th-closest miss on record.
It was the second hunt of hurtling space rock to come near the planet in two days.
The day before, a 64-foot asteroid flew past Earth about 32,000 miles away.
Footage of tonight's asteroid fly-by can be seen on the Slooh website at http://events.slooh.com/
