The asteroid, named Florence, is an almost 3-mile-wide rock that passed about 4.4 million miles from Earth
(7 million kilometers) early Friday, NASA says.
And while a few million miles sounds like a lot of room, it's actually a pretty close pass when you're talking about the vastness of space. Other asteroids have passed closer to Earth than Florence, but few have been this big.
"Florence is the largest asteroid to pass by our planet this close since the NASA program to detect and track near-Earth asteroids began," Paul Chodas, manager of NASA's Center for Near-Earth Object Studies,
said in a statement
It was Florence's closest flyby of Earth since 1890 -- and the closest it will get until after 2500.
But there's no need to get Bruce Willis and his crew
involved. Florence doesn't pose any immediate threat, Chodas told CNN in an email interview.
"Certainly not for the next several centuries, and not likely over the next many millennia either," he said. "It's possible this asteroid could threaten our planet in the far distant future, but it's unlikely."
A learning opportunity
Florence -- named to honor of Florence Nightingale,
the founder of modern nursing -- does offer a great opportunity. Scientists think any asteroid larger than half-mile to a mile
(1 to 2 kilometers) in size could have worldwide effects if it hit the planet, so they studied Florence as it zipped by.
Radar images snapped by the Goldstone Solar System Radar
in California and the National Science Foundation's Arecibo Observatory
in Puerto Rico will help scientists learn more about the asteroid's composition, shape, surface properties and roughness and the presence of boulders, Chodas said. They also may learn whether Florence has a satellite.
Having Florence do a flyby is a lot easier than chasing down an asteroid in space -- though NASA is doing that, too, with its OSIRIS-REx mission.
The spacecraft was launched in September 2016 to chase down a potentially dangerous asteroid called Bennu. It will take a sample of the asteroid and -- in a US space first -- bring the sample back to Earth.
The asteroid that does pose a threat
About once a year, a car-sized asteroid hits Earth's atmosphere
and creates a big fireball, NASA says. These don't usually cause damage. But in February 2013, an asteroid streaked through our atmosphere
and exploded over Chelyabinsk, Russia.
The rock was about 59 feet (18 meters) wide and weighed 11,000 metric tons, according to NASA. It exploded about 14.5 miles (23.3 kilometers) above Chelyabinsk, injuring hundreds of people and shattering glass in buildings.
The asteroid that currently poses the biggest threat to Earth, according to Chodas, is Asteroid 1950 DA.
It could "impact in the year 2880," he said. That asteroid is about 1 mile wide (1.3 kilometers), and the chances for an impact with Earth are 1 in 8,000.
So, what is NASA doing about all these dangerous space rocks? They created an office in 2016 that sounds like something out of "Star Wars"
: the Planetary Defense Coordination Office.
It's tasked with helping find dangerous asteroids and comets, and it's leading US government efforts to develop a plan to respond to an actual impact threat.
Early plans are focused on finding threatening space objects
and -- one day -- being able to break them apart or deflect them from Earth.
A rock star and space rocks
And NASA scientists aren't the only ones interested in asteroids. Astrophysicist Brian May, better known as the lead guitarist for the rock band Queen, helped create Asteroid Day
in 2015 to educate the public about the dangers of asteroids.
May's co-founders include astronaut Rusty Schweickart, film director Grigorij Richters, and Danica Remy, chief operations officer of the B612 Foundation, a nonprofit that aims to protect Earth from asteroids through early detection. The United Nations has sanctioned the holiday as a global day of education to raise awareness. The next Asteroid Day is Saturday, June 30, 2018.