The asteroid, named 2018 AJ, is just one of several asteroids that have suddenly popped up on NASA’s radar without warning-the last one was 2017 YD7, which was spotted December 28 and flew past Earth on January 3.
The scary thing about these rocks is that once we spotted them, there’s very little we can do to stop them: according to NASA’s Planetary Defense Coordination Office, we’d need a few decades of advance warning to deal with an asteroid 100 meters in size or larger. From there, a couple options open up, including knocking the asteroid off course with a “kinetic impactor” or using a “gravity tractor” to change its trajectory.
All of this, however, would take years to accomplish. When it comes to simply shooting an asteroid out of the sky with, say, a nuclear warhead, NASA’s stance is pretty clear: “No known weapon system could stop the mass because of the velocity at which it travels-an average of 12 miles per second.”
An asteroid doesn’t have to be a giant in order to wreak mass destruction, however-the Chelyabinsk meteor was about 17 meters in diameter and weighed approximately 10,000 metric tons, and it still made it through Earth’s atmosphere, exploding with the force of around 470 kilotons of TNT and causing thousands of injuries just from breaking nearby windows.
Though NASA’s Planetary Defense office says the next big asteroid threat won’t happen until 2185, that doesn’t take into account all the asteroids they keep missing-and that number may keep rising in 2018.