Our planet witnessed three close shaves this week - on Wednesday and Thursday, three asteroids flew by Earth at a distance less than the distance of the moon from the Earth.
Over the last few decades, people are growing increasingly concerned about the risk of a giant space rock crashing into the planet. While the danger is very real as evidenced by the 2013 Chelyabinsk incident, near misses are actually pretty common. NASA scientists estimate that around 20 known asteroids pass very close to the Earth every year.
"This is not an unusual event," said Near-Earth Object Program Office senior scientist Paul Chodas. "Objects of this size pass this close to the Earth several times every year."
The space rock, named Asteroid 2014 EC, was actually the third asteroid to fly by the planet this week. Last Wednesday, two asteroids buzzed by the Earth. The first one passed by at a distance of 217,000 miles while the second asteroid passed by at a distance of 105,000 miles. While these near misses might not seem so near at first glance, these distances are actually very small in astronomical terms. For comparison's sake, the distance between the Earth and the moon is 238,900 miles.
Asteroid 2014 DX110, one of the space rocks that flew by last Wednesday, is about 98 feet long and it flew past the Earth at a speed of 33,000 miles per hour. On the other hand, Asteroid 2014 EC is around 25 feet across. While a lot smaller than Wednesday's asteroids, the third asteroid flew by Earth a mere 38,300 miles away. This distance is around one sixth the distance of the moon from the Earth.
Asteroid 2014 EC was spotted by scientists on Tuesday night, which means that NASA would have had little time to react if the asteroid was headed on a collision course for Earth. These near-Earth objects are studied, catalogued and tracked by Spaceguard as part of the activities of the Near-earth Object Observations Program.
Given the danger these near-Earth objects pose, NASA has been exploring a number of possible countermeasures to deflect or destroy potentially dangerous asteroids. One of NASA's asteroid defense plans involves sending a robotic probe to potentially dangerous asteroids. These probes can then attempt to move a target asteroid to a stable orbit around the moon. However, these plans have not yet been tested and NASA is hoping to change that in the coming years.