Asteroid CY2 is the fastest of the three asteroids, swinging past the planet at breakneck speeds of around 29,415mph or 13.15km per second.
Thankfully, the asteroid did not hit our home world despite making an incredibly close approach.
At its closest, NASA estimates the rock came within 1.9 million miles (3.07 million km) of striking Earth.
This is the equivalent of eight times the distance from the Earth to the Moon.
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NASA asteroid tracker: Three giant space rocks are making so-called Earth Close Approaches today (Image: GETTY)
NASA’s initial size estimates show Asteroid CY2 measures somewhere in the range of 39.4ft to 85.3ft (12m to 26m) in diameter.
Asteroid CG4, which will zip by just before noon, is the smallest of the asteroids and would pose a minimal amount of danger if it were on a direct collision course with Earth.
At its closest, CG4 will approach Earth from 0.00459 astronomical units (au) or 426,667 miles (686,654km).
Astronomical units are used to define the average distance from the Earth to the Sun – about 93 million miles (149.6 million km).
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Thousands of asteroids and comets known as “Near Earth Objects” fly past the Earth every year but rarely do they strike and cause damage.
Once every few million years, an object large enough to threaten Earth’s civilisation comes along
The smaller space rocks typically disintegrate in the atmosphere before they can hit the ground with great force.
Occasionally one or two asteroids will slip through and remind astronomers of the dangers lurking in the depths of space.
This happened in 2013 when a 65.6ft-wide (20m) asteroid, dubbed the Chelyabinsk Meteor, exploded over Russia and injured more than 1,000 people with shards of glass from broken windows.
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The asteroid blew up with 30-times the force of the Hiroshima nuclear bomb and damaged more than 7,000 buildings.
Today’s close flyby of the three asteroids is a reminder of the hundreds of thousands of asteroids and comets barrelling around the solar system every single day.
NASA said: “Every day, Earth is bombarded with more than 100 tons of dust and sand-sized particles.
“About once a year, an automobile-sized asteroid hits Earth’s atmosphere, creates an impressive fireball, and burns up before reaching the surface.
NASA asteroid tracker: Big space rocks rarely strike Earth and deal damage to the planet (Image: NASA)
NASA asteroid tracker: None of the three asteroids are expected to hit the planet today (Image: GETTY)
“Every 2,000 years or so, a meteoroid the size of a football field hits Earth and causes significant damage to the area.
“Finally, only once every few million years, an object large enough to threaten Earth’s civilisation comes along.”
The last of the three space rocks entering Earth’s corner of space today is Asteroid PV25 – the biggest and slowest of the three asteroids.
Asteroid CY2 is estimated to measure somewhere in the range of 104.9ft to 232.9ft (32m to 71m) across, meaning it is 8.4-times longer than a London double-decker bus.
The asteroid will swing by at speeds of around 13,622mph or 6.09km per second and will approach the planet from about 1.73 million miles (2.79 million km).