The asteroid is hurtling our way at 20,000mph and is expected to “skim past” our planet on Wednesday.
It’s known as 2016 NF23 and measures 500ft in diameter.
That’s bigger than the Great Pyramid of Giza in Egypt which stands at 451ft.
The US space agency NASA has slapped it on its “potentially hazardous asteroid” list.
That’s because it’s expected to pass within 0.03377 astronomical units, or about three million miles, from Earth.
It’s considered close in terms of our galaxy – the Sun is 93million miles away.
NASA classify asteroids as “potentially hazardous” if they are within 4.6million miles of Earth.
And the space agency has finally broken its silence about the huge rock.
Lindley Johnson, a planetary defence officer at Nasa’s Headquarters in Washington, poured cold water on the suggestion the asteroid was dangerous.
He said that it in fact posed no risk.
He told Space.com: “There is absolutely nothing for concern by this pass of 2016 NF23.
“This object is merely designated a Potentially Hazardous Asteroid (PHA) because its orbit over time wings it within five million miles of Earth’s orbit, but there is nothing hazardous to Earth or even unique about this pass of the asteroid.”
This comes as a bus-sized asteroid zoomed past Earth earlier this month in the closest approach of the year.
But despite that, NASA still missed the 15-metre space rock that flew past at 20,636 miles.
The space agency didn’t find the rock until the day after.
Amateur astronomer and high school physics teacher Tony Dunn explained on Twitter the asteroid was “undiscoverable prior to closest approach because it came from the direction of the Sun”.