A fireball streaked across the skies of southern Ontario early on November 19 as asteroid 2022 WJ1 burned up upon atmospheric entry. This is not unusual—meteors frequently strike Earth—but this time, NASA was able to predict when and where the meteor would impact. This was especially impressive because, at roughly a meter wide, 2022 WJ1 was the smallest asteroid yet discovered in space.

NASA’s prediction resulted from the coordinated effort of human astronomers and automated systems. The Catalina Sky Survey in Tucson, Arizona, identified the asteroid only 3.5 hours before impact. The observations were reported to the Minor Planet Center, which posted data retrieved by Scout, NASA’s automated impact hazard assessment system. Within seven minutes, Scout calculated the object’s trajectory and concluded that 2022 WJ1 had a 25% probability of striking Earth at locations ranging from Mexico to the Atlantic Ocean off North America. After seeing these results, amateur astronomers at Farpoint Observatory in Kansas tracked the asteroid for more than an hour, uploading additional data that permitted Scout to calculate a 100% impact probability with atmospheric entry over southern Ontario at 3:27 a.m. EST. Over the intervening hours before impact, professionals and amateurs collected an additional 44 observations. The asteroid entered Earth’s atmosphere over Brantford, Ontario, at 3:27 a.m. EST. Weather radar detected fragments of the meteor falling as meteorites. While most landed in Lake Ontario, some meteorites may be found south of the lake near Grimsby and McNab, Ontario.

2022 WJ1 was not a hazard to humanity. However, this short-warning event was a good test of our capability to discover, track, and predict larger near-Earth objects (NEOs). The future launch of telescopes like the NEO Survey will improve our ability to detect these threats, while missions like the Double Asteroid Redirection Test (DART) will enhance our ability to guard against them. READ MORE