Two asteroids have already zipped past the Earth and the third will flyby in the late evening hours, just before midnight around 11.44pm BST (10.44pm UT).
The first space rock, dubbed asteroid 2018 RM7, reached its closest distance to Earth around 6.17am BST (5.17am UT) in the morning.
NASA estimates Asteroid RM7 came within 2.78 lunar distances of the planet – nearly three times the distance to the Moon or 663,704.46 miles (1.06 million km).
The asteroid flew by at breakneck speeds of around 38877.9 mph (17.38 km per second).
The USA-based space agency believes the space rock measures anywhere between 20.6ft and 14 (6.3m to 14m).
The second of the asteroid trio, Asteroid 2018 RK6, came slightly closer to Earth around 11.35am BST (10.35am UT) but was much slower.
NASA calculated RK6’s path brought it within 2.41 lunar distances of Earth or 576,326.01 miles (927,506.8 km).
The space rock flew by at a much slower than it’s speeding cousin RK7, reaching a relative speed of just 14,226 mph (6.36 km per second).
Read more: Asteroid size of a VILLAGE could smash into Earth in 2028
NASA asteroid warning: Three massive space rocks are zipping past the planet today (Image: GETTY)
NASA’s table of Earth Close Approaches shows the asteroid measures somewhere between 22.3ft and 49.2ft (6.8m to 15m).
According to the space agency’s Jet Propulsion Laboratory (JPL) in Pasadena, California, Asteroid RK6 last visited Earth in December 2013 and December 2008.
In January 2016, the asteroid also skimmed the planet Mars on its way to Earth.
Thankfully for Earth, NASA does not predict any future close encounters with RK6.
Read more: Scientists to nudge asteroids towards EARTH
The third asteroid to swing by tonight will be the largest of the three and NASA thinks it could measure between 36ft and 82ft (11m and 25m).
If Sentry finds potential impacts for an object, we add it to our online impact risk table
The upper range of NASA’s size estimate suggests the space rock is twice as wide as London double-decker bus is long.
The asteroid, dubbed Asteroid 2018 RQ4, will pass the planet late tonight around 11.44pm BST (10.44pm UT).
Asteroid RQ4 will then make two more visits to Earth on December 24, 2022, and November 29, 2063.
Read more: Asteroid bigger than St Paul’s Cathedral whizzes THIS close past Earth
NASA asteroid warning: The largest of the three asteroids could measure 82ft in diameter (Image: GETTY)
Stargazers hoping to catch a glimpse of the giant rock tonight will be disappointed to learn the asteroid will zoom by from a distance of 2.83 million miles (4.565 million km).
This incredibly vast distance is roughly equal to 11.87 times the average distance between the Earth and the Moon.
But as in the case of the previous two space rocks, the distance is small enough within the confines of the solar system to warrant interest from NASA’s asteroid trackers.
NASA has classified all three asteroids as so-called Near-Earth Object or NEOs.
NEOs are asteroids and comets which come within 30 million miles (50 million km) of the Earth’s orbit around the Sun.
NASA asteroid warning: Another six asteroids will come very close to Earth this month (Image: GETTY)
If a space rock is big enough and close enough to Earth, NASA labels it a Potentially Hazardous Asteroid (PHA).
Steve Chesley, an asteroid researcher at JPL, said these asteroids are tracked by NASA’s Center for Near-Earth Object Studies (CNEOS) Sentry system.
He said: “If Sentry finds potential impacts for an object, we add it to our online impact risk table and asteroid observers can then prioritise that object for further observation.
“The more measurements made of the object’s position over time, the better we can predict its future path.”
In September alone, another six NEOs will make a Close Earth Approach between September 18 and September 24.