Back in the 1990s, movies like “Armageddon” and “Deep Impact” helped show the world what it could be like if humanity met its end in a massive asteroid impact like our Jurassic (okay, technically Cretaceous) predecessors. In these movies, mankind utilized the best (science fiction) technology available to prepare for and attempt to prevent the impending disaster. As unrealistic as some of their solutions may have seemed, perhaps the least realistic aspect of those movies was actually that we saw the asteroids coming at all.

It was only this past week that scientists announced with confidence that a large meteor exploded in Earth’s atmosphere over the Bering Sea this past December. The explosion it produced released ten times the destructive force of the atom bomb dropped on Hiroshima near the close of World War II. It was, according to their estimates, the third largest explosion of its kind in recorded history, with the 1908 Tunguska event taking the top spot and Russia’s highly-covered Chelyabinsk event from six years ago ranking second.

All of that destructive capability was delivered in a fairly small package. The meteor measured only about 30 feet in diameter and weighed about 1,500 tons. At around noon on December 18, the meteor impacted Earth’s atmosphere somewhere between Alaska and Russia over a remote expanse of the Bering Sea. It was traveling at around 72,000 miles per hour at a steep trajectory until exploding only about 16 miles above the Earth’s surface.

The explosion itself was actually spotted right away by a number of military and civilian instruments located throughout the region recording data like infrasound (low frequency sounds humans often can’t hear) and electromagnetic radiation.

The meteor explosion went largely unnoticed, however, in part because no one spotted it as it approached in real time, and also because it blew up over such a remote area. Had the meteor exploded over a populated city, it could have resulted in significant damage, not unlike shown in videos of the Chelyabinsk meteor in Russia in 2013. After the event, scientists were able to confirm what the meteor was and where it traveled by checking satellite data and imagery captured from platforms like the Japan Meteorological Agency’s Himawari-8 weather satellite.

NASA’s office of Planetary Defense tracks near-Earth objects (NEOs) that could potentially pose a threat, but they acknowledge there are likely far more threats out there than they know about. NASA claims it discovers an average of 30 potentially-threatening NEOs each week, with the total number sitting at well over 19,000.

Of those 19,000 NEOs, roughly half are over 460 feet in diameter, which NASA considers to be large enough to cause regional effects if it were to impact Earth. Although only 9,000 or so of these objects have been spotted, NASA estimates there are at least 25,000 in our planetary neighborhood. Objects measuring over 984 feet are considered to be capable of having near-global effects.

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“Ground-based telescopes alone have limitations. For instance, they can only survey the skies at night and in clear skies. Based on statistical population estimates, about two-thirds of NEOs larger than 460 feet still remain to be discovered,” NASA says on its website.


Feature image courtesy of NASA