Don't Panic!

After a meteor violently exploded over the southern city of Chelyabinsk, Russia last February, media outlets closely reported the horrific aftermath. The 20-meter long asteroid caused nearby windows to shatter and witnesses noted an intense heat radiating from it. The asteroid became the largest external object to enter Earth’s atmosphere since a similarly massive comet exploded over northern Siberia in 1908. International media sources flew into an uproar; Russia’s Prime Minister called the “entire planet” vulnerable to meteor collisions and implored the government to form of an asteroid protection program, the United Nations vowed to assemble an “International Asteroid Warning Group,” and White House science advisor John Holdren warned members of Congress that “there may be hundreds of thousands of such objects within one-third the distance from Earth to the sun that remain unknown.” Should the public be shocked by these findings? Is the violent demise of current civilization inevitable? 

Probably not. The odds that an asteroid will impact the future of civilization are exceedingly low. Thousands of non-planetary objects orbit the sun. While most are confined to the asteroid belt between Mars and Jupiter, some have been nudged slightly from of their original orbits by a gravitational attraction to other nearby massive objects. The paths of these Near-Earth asteroids, or NEAs, can troublingly intersect with Earth’s orbit around the sun. To estimate the paths of these rocky remnants of the solar system’s formation, researchers capture photos of the asteroid across several days and model a likely course. As the asteroid travels closer to Earth, uncertainties in calculation can be lessened and the probability that the object will collide with the planet is raised or reduced. 

However, in the vast majority of asteroid observation cases, the probability of impact is steadily reduced to nearly zero over a period of months of observation. Programs such as MIT’s Asteroid Research project and NASA’s Near Earth Object Program closely monitor NEAs and assess their risk to Earth on the Torino Impact Hazard scale.

This measurement system plots the potential danger of an oncoming asteroid from 0 (no likelihood of collision) into a red zone from 8 to 10 (certain collision). Of the hundreds of asteroids currently being monitored by these programs, all but one are ranked 0 on the Torino scale. The sole potential hazardous object, 2007 VK184, is allotted a mere 1, indicating the asteroid possesses no unusual level of danger; its likelihood of impact when it passes near Earth in 2048 is 5.7 x 10-4 . Probabilistically, a Torino 10 asteroid with the potential to impact the global climate of Earth will collide with the planet only once in every 100,000 years. Even 99942 Apophis, an object that was ominously labeled the “doomsday asteroid” upon its discovery in 2004, was downgraded from a concerning Torino 4 to a level 0, pegging its odds of collision at 1 in 256,000.

Even if an asteroid enters the Earth’s atmosphere, it must cope with the discrepancy between effortlessly traveling through the vacuum of space and moving through air. When entering the atmosphere, the air in front of the object compresses at an incredibly fast rate, releasing heat and reducing the size of the meteor dramatically. Upon entering the atmosphere, the meteor as a 3% chance of actually hitting a densely populated urban area, for the vast majority of Earth’s surface remains uninhabited or covered in water. The odds of a fiery and apocalyptical end by asteroid collision are uneventfully low. Although death by asteroid remains a fantastically interesting way to die, while such odds remain, by one estimate, 1 in 74,817,414, humans should divert their panic to more domestic threats.

Laura Gunsalus