Given all the warnings about near-miss asteroids and the calls for a deflection system for warding off potential impactors, what would actually happen if a “city killer” asteroid slammed into Manhattan in New York City? Or what if an even larger space rock or comet impacted Chicago? A new study took a look at the possibility of just such occurrences and came up with some disturbingly large numbers associated with the devastation that would ensue.
New York City is one of the world’s largest cities, its five boroughs combining for a population total of 8.4 million (as of 2013, according to the U.S. Bureau of the Census), and a direct asteroid hit (or airburst just above the island of Manhattan) would be a terrible economic and demographic blow to the world should it find itself an impact site. As the Daily Mail reported, a recent study indicates that an asteroid measuring just 100 meters (328 feet) would flatten buildings for over two miles and kill over 2.5 million people. The fireball would extend nearly two miles and produce thermal radiation that would be felt up to 12 miles away, where individuals in Yonkers, New York or Newark, New Jersey would suffer burns.
The study, which was conducted by InsuranceQuotes, relied on the NASA Near-Earth Object Program database of 36,000 close approaches to Earth for its analysis. Researchers used an impact calculator to determine the energy of the NEOs (Near-Earth Objects), and then converted this into yields measured in megatons of TNT. To simulate the possible devastation of an impact, the study used a tool called Nukemap.
The New York City impactor was modeled after a recent fly-by of asteroid 2013 FK, which measures 100 meters (328 feet) across, the minimum diameter of an asteroid or comet considered a Potentially Hazardous Object by NASA. Potential impactors of this size (and those 140 meters and smaller) are known as “city killers” by Congress, according to Stanford University physicist Richard Blandford (per Space News). And for good reason. The 1908 Tunguska Event, which saw a meteor estimated to be 45 meters (148 feet) across flatten the forest in southern central Russia in an area as large as New York City.
The study also looked at potential impactors for the cities of San Francisco and Chicago. The death toll in these cities would be nine and 9.5 million respectively, even though the asteroid slamming into Chicago is modeled to be twice as big (550 meters, or 1805 feet compared to 300 meters, or 984 feet). The reason for the high death toll in San Francisco? The simulation sees the asteroid landing partially in the Pacific Ocean, but it would trigger tsunamis and earthquakes, causing even more death and destruction than a simple land impact.
The study also noted the NEOs that would come closest to Earth in 2017. At the time of the study (late January), the closest was set to make a near-miss just within the Moon’s orbit. But these five were asteroids already known to NASA and the Near-Earth Object Program.
It is the asteroids and comets that have yet to be found — and there are an estimated tens of thousands — that are the most worrisome.
On March 4, a previously undetected asteroid flew by, missing the Earth by just 9,000 miles (14,484 kilometers) after slicing through the outer perimeter of satellites orbiting Earth. That asteroid, designated 2017 EA, was first sighted only six hours prior to its fly-by.
Fortunately, 2017 EA was only about 10-feet wide, so if it had entered Earth’s atmosphere, it likely would have done little to no damage.
But as the study from InsuranceQuotes illustrates, an asteroid making a direct hit on Earth could prove extremely devastating should it impact inside or near a major city on the planet. And without a more efficient detection and/or mitigation/deflection system in place, a “city killer” might be the least of mankind’s problems. Humanity might face an extinction level event from a massive asteroid or comet that has yet to be discovered.
[Featured Image by puchan/Shutterstock]