Astronomers spotted an asteroid as big as a Walmart store or a city block just hours before it buzzed our planet Saturday.
Asteroid 2018 GE3 could be several times bigger than the meteor that exploded over Chelyabinsk, Russia, five years ago, creating a shockwave that blew out thousands of windows in the city of Chelyabinsk, causing hundreds of minor injuries.
The Catalina Sky Survey and Steward Observatory in Arizona first observed Asteroid 2018 GE3 in the early morning hours on Saturday. Less than 24 hours later, it came within about half of the distance between us and the moon, or 119,000 miles (192,000 kilometers) from the surface of the planet.
It's common for asteroids to be spotted for the very first time at this relatively close distance, but this particular space rock is among the largest ever to come that close to the surface of our planet. A couple of times a week, on average, an asteroid will come closer than the distance to the moon, but most of those are hunks about the size of a bus or maybe a house.
2018 GE3, by comparison, is between 200 and 400 feet (48-110 meters) in diameter, or more like the size of a large warehouse. That makes it two to five times larger than the bolide that unexpectedly collided with the atmosphere above Russia in 2013.
Wikipedia and other sources are currently reporting that this is the largest asteroid to ever pass this close to Earth. However, a search of NASA near-Earth object observation data shows that a couple of larger asteroids passed within half the distance to the moon, one in 2001 and one in 2002.
But we are set for a real close call in almost exactly 11 years from now, when the asteroid 99942 Apophis will pass closer to us than the orbit of many man-made satellites on April 13, 2029. Apophis is a menacing asteroid that could be 10 times the size of 2018 GE3. But don't worry, it's still highly unlikely to hit us.
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