If an object the size of Dimorphos were to hit us, it would be “a bad day for whichever part of the world it landed on,” says Andy Rivkin, a planetary astronomer at Johns Hopkins University’s Applied Physics Laboratory in Maryland and a co-lead investigator for the DART mission. The whole affair will be closely monitored by a small satellite travelling alongside DART, and by telescopes on Earth. The impact is predicted to alter the object’s orbit slightly, making it spin just a bit faster around Didymos. The spacecraft will target Dimorphos, the smaller of the two at about 525 feet across (a bit wider than the largest of the Egyptian pyramids). Next fall, the DART spacecraft, about the size of a vending machine, will reach Didymos and Dimorphos, a double asteroid system that revolves around the sun between the orbits of Earth and Mars (though at its furthest, it actually lies a tad beyond the Red Planet). In fact, NASA’s DART mission (Double Asteroid Redirection Test), which launched on November 23, is the first spacecraft designed to ram into an asteroid to see how the object’s orbit is affected. Scientists have considered a number of strategies for dealing with such an object, if one were detected. Those who remember 1998 may recall over-the-top fare like Armageddon, or the somewhat more scientifically plausible Deep Impact, which shared a broadly similar doomsday premise.įor Hollywood, wayward comets and asteroids are plot devices, but astronomers and physicists take the threat very seriously. The darkly comedic satire from the mind of Adam McKay, the writer and director of The Big Short and Vice, hits theaters on December 10 and comes to Netflix on December 24. The drama of such a cosmic collision hasn’t been lost on Hollywood, whose latest offering on the subject, Don’t Look Up, involves an Earth-bound killer comet. “Even a relatively small asteroid, say 150 meters across could take out a major city,” says Leslie Looney, an astronomer at the University of Illinois, Urbana-Champaign.

Nonetheless, it pays to be prepared, given the devastation that such an impact would bring. To be very clear, no asteroids or comets are currently known to present any danger. It might be an asteroid–a big chunk of rock, orbiting the sun in the inner part of the solar system–or it might be a comet, containing ice as well as rock, and typically moving in a slower, more oval-shaped orbit. It’s not a question of if but when: Eventually, astronomers will discover a celestial object on an Earth-bound trajectory.

Comet heading towards earth