Image courtesy Ernesto Guido, Nick Howes, and Giovanni Sostero
Published June 27, 2011
An asteroid the size of a school bus gave Earth an extremely close shave around 1:14 p.m. ET today.
The rogue object—dubbed asteroid 2011 MD—buzzed by at a distance of 7,500 miles (12,000 kilometers) from our planet's surface, or roughly 30 times closer than the moon.
Researchers with MIT's Lincoln Near Earth Asteroid Research (LINEAR) program discovered the asteroid on June 22 and pegged its size between 20 feet (6.3 meters) and 46 feet (14 meters) wide.
Astronomers clocked its top speed at around 63,000 miles (101,000 kilometers) an hour.
Although small by asteroid standards, 2011 MD was close enough for amateur astronomers to spot it with modest telescopes.
Watch video of the asteroid taken June 26 with a 20-inch backyard telescope.
If the asteroid had been on a collision course with Earth, the space rock would have been large enough and fast enough that it would have made it to the ground, said MIT planetary scientist Ben Weiss.
"You'd end up with some sort of explosion and a decent-size crater," he said. "You wouldn't have wanted something like this to land in Manhattan."
Future Asteroid Impact Inevitable
About one asteroid around the same size as 2011 MD comes as close to Earth every five to ten years, and one strikes Earth roughly once every 50 years.
"This was not an extraordinary event in the world of close asteroid approaches," Weiss said.
"We've recently tracked five other objects that came closer, and a small one of these actually fell to Earth."
"Sooner or later," Weiss said, "a bigger one is going to hit us."
Newfound Asteroid May Be Back
Asteroid 2011 MD is considered an Apollo-type asteroid, because its orbit is very similar to Earth's yet longer in duration and more oval-shaped.
Astronomers expect the space rock to swing by again in the future—perhaps more closely the next time around—but it's tough to know for certain until the asteroid's departure path is measured in detail.
Short of hitting Earth, the closest asteroid flyby ever recorded was made by a space rock called 2011 CQ1. It passed 3,400 miles (5,480 kilometers) above Earth on February 4, 2011.
Special Ad Section
Our new Phenomena space blogger, Nadia Drake, will be bringing you tales from beyond our home planet.
Video of the Day
When the trembling stops, the disaster is only the beginning. Learn the basics about earthquakes.