Named 2017 YZ4, the space rock only came into view on Christmas Day and will pass between the Earth and the Moon on Thursday, December 28.
The distance will be in the region of 140,000 miles — close enough to be considered a "near miss" by astronomers, who will watch it closely.
Reputed to be the size of a double decker bus, the asteroid will whizz past Earth at around 4.56pm (11.56 ET) with NASA scientists on full alert to study its appearance.
The asteroid was first spotted at Mount Lemmon Survey Observatory in Arizona and will be the 52nd to pass between the Earth and the Moon this year.
A ~10-meter asteroid, 2017 YZ4, will make a really close flyby of Earth today (0.58 Lunar Distance) pic.twitter.com/8iaKt1FSm4
— Ron Baalke (@RonBaalke) 28 December 2017
"This is the first known asteroid to fly by Earth within one lunar distance since two such asteroids flew past us 35 minutes apart on November 21, and the 52nd this year", a NASA spokesperson said.
"As of December 24, there are 17,495 known Near-Earth Objects (NEOs) around our planet; 17,389 are asteroids. This year, we discovered 1,985 new near-Earth asteroids. There were 1,888 such objects discovered in 2016 and 1,571 in 2015."
Close Encounter
Anything that flies closer than six million miles of our planet is a near-Earth asteroid and could cause severe damage were it ever to crash into Earth.
In February 2013 a 62-feet (19-meter) meteor exploded in the skies above Chelyabinsk in Russia.
2017 YZ4: Newly-discovered Asteroid to Come Close to Earth Today https://t.co/Pn843hqpY3 pic.twitter.com/woSEF8zQdn
— Space Newz (@Space__Newz) 28 December 2017
The energy — which was equivalent to 500,000 tonnes of TNT — injured more than 1,000 people.
Earlier this month a massive asteroid called 3200 Phaethon made its closest approach to Earth at around 6.4 million miles (10.3 million kilometers) away.
The new observations conducted from December 15-19 show Phaethon to be about 3.6 miles (six kilometers) wide.
Larger than first thought
Although this latest rock is 22.6 to 49 feet in diameter (seven to 15 meters) it is larger than previously thought.
It actually passed by Earth this month at about 27 times the distance between our planet and the Moon.
I can’t think of a better movie theater to watch Star Wars than on the @Space_Station! pic.twitter.com/pnybkUSs4a
— Joseph M. Acaba (@AstroAcaba) 27 December 2017
Before its approach, NASA revealed asteroid 3200 Phaethon had been classed as "potentially hazardous."
The latest approach is the closest the asteroid has been to Earth since December 16, 1974, when it was around five million miles away — although most were blissfully unaware at the time.
"With a diameter of about 5km, Phaethon is the third largest near-Earth asteroid classified as 'potentially hazardous'," said a NASA spokesperson about the asteroid, which was first discovered in 1983.
The next pass is predicted to be in 2093 when it is expected to pass at just over 1.8 million miles (2.9 million kilometres) away.
