Comets and Near-Earth Asteroids

‍The new Netflix film Don’t Look Up features Leonardo DiCaprio and Jennifer Lawrence as astronomers who discover that a previously unknown comet will collide with Earth in about six months. Despite their repeated pleas, the media and government ignore their requests to act immediately to save the planet. While this film is meant as a satire of climate change and overall science skepticism, it puts to the forefront of American media an idea also floated back in 1998 with the releases of Armageddon and Deep Impact.

With similar plots, objects of tremendous size are found to be hurtling toward us with little time to avert a major catastrophe. The premise of “a last-ditch effort to save humanity by launching a spacecraft laden with nukes” guides each of these stories on slightly different trajectories, the overall premise being that we can save Earth from a newly discovered object before it slams into our planet by blowing it up with our biggest weapons of war — right?

In today’s reality astronomers really are looking to the sky in hopes of finding near-earth objects — NEOs— that could cross paths with our planet in the future. Much if this work is done in Southern Arizona’s Santa Catalina Mountains, in a partnership between the University of Arizona and NASA known as the Catalina Sky Survey.

Using a 1.5-meter telescope equipped with a 111-megapixel camera, the team takes a series of 30-second exposures to capture objects that would be impossible to locate with most land-based equipment. Using software to compare the resulting images, they can isolate objects moving across the background of distant stars, identifying them as either known or previously unknown objects of interest. Follow up observations with other telescopes dotting the mountains outside Tucson help calculate orbits and plot where those orbits might intersect with Earth in the future.

Gregory Leonard leads the team at the Catalina Sky Survey, and is often first to report newly discovered objects in our solar system. His resume includes discovery of more than 1,600 NEOs and 13 comets, including comet C/2021 A1 Leonard, which graced our morning skies in early December and evening skies later in the month.

On November 23 NASA and the ESA launched the DART spacecraft, for an October 2022 rendezvous with a binary asteroid that poses no threat to Earth, to study whether we can divert an asteroid given enough time. After it slams into its target, ground-based observations at Lowell Observatory in Flagstaff and other telescopes around the country and world will track the change in the asteroid’s orbit to determine how much mass is needed to move a body like this.