An asteroid the size of three blue whales just zoomed past Earth, but don't worry, Earthlings were not at risk from this space rock.
The asteroid missed the planet by more than 2.2 million miles (3.5 million kilometers), about 10 times the moon-Earth distance, at its closest approach, which occurred Monday morning (June 6). The asteroid, known as 2021 GT2, is between 121 and 272 feet (37 to 83 meters) wide, which means it could wipe out a city, if it were to hit Earth. Fortunately, space is big, and the absolute majority of these rocks miss us.
2021 GT2, hurtling through space at a mind-boggling speed of 16,000 mph (26,000 kph), is a so-called Aten asteroid, a type of asteroid that circles the sun in an orbit that is quite similar to that of Earth. The Aten asteroids make closer approaches to the sun than our planet approaches the sun, but because their orbits are a bit more elliptical, they regularly cross our planet's path.
2021 GT2, discovered last year, orbits the sun every 342 days and is one of 1,800 Aten asteroids currently known. The next "close" encounter between 2021 GT2 and Earth will take place in January 2034. That encounter will pose no risk to Earth either, as the two bodies will pass each other at a distance of 9 million miles (14.6 million km), more than four times farther away than they did this time.
Astronomers currently don't know of any large asteroids that will collide with Earth in the coming century or so. But there are many asteroids out there that astronomers haven't discovered yet, or the orbits of which are not yet perfectly known.
In February 2013, an asteroid only 62 feet (19 m) wide exploded near the Russian town of Chelyabinsk. Although the space rock passed 25 miles (40 km) from the city, the shock wave that the explosion generated shattered over 3,600 windows and injured 1,500 people in the city.