Scientists Spot Oncoming Asteroid Just Hours Before Impact: ScienceAlert
For only the sixth time in recorded history, astronomers have caught a glimpse of one an asteroid before hitting Earth.
On November 19, 2022, nearly four hours before impact, the Catalina Sky Survey detected an asteroid called 2022 WJ1 on an inbound trajectory. A network of telescopes and scientists swung into action, precisely calculating exactly when and where on the globe the asteroid would hit.
This is excellent news. 2022 WJ1 was too small to cause serious damage, but its discovery shows that the world’s asteroid monitoring techniques are improving, giving us a better chance of protecting ourselves from falling space rocks — the big ones that could really cause damage.
Although space is mostly space, it also has a bunch of non-space in it. Near Earth, this void is mostly asteroids that orbit the Sun in such a way that brings them closer to Earth’s orbit. We call them near-Earth asteroids, and at the time of writing, 30,656 of them have been catalogued.
Most of these asteroids are actually quite small, and scientists are confident that we have found almost all of them that are large enough to pose a significant hazard, studied them, and found that none of them will come close enough in the next century, to be a threat.
Still, it’s good to keep abreast of what’s buzzing around in the space around us and hone our sneaky rock-finding abilities while thinking of making a grand entrance.
frameborder=”0″ allow=”accelerometer; automatic execution; clipboard-recording; encrypted media; gyroscope; picture in picture” allowfullscreen>
The opening 2022 WJ1 was taken at 04:53 UTC on November 19, 2022 by the Mount Lemmon Observatory, part of the Catalina network. He continued to observe the object, taking four images that allowed astronomers to confirm the discovery and report it to IAU Minor Planet Center at 05:38 UTC.
Those four images were enough to calculate the asteroid’s trajectory across the sky, with multiple impact monitoring programs finding that the rock had about a 20 percent chance of landing somewhere on the North American continent.
Subsequent observations allowed the scientists to refine their measurements by giving time and location. Bursting on schedule, at 08:27 UTC, 2022 WJ1 was seen streaking across the sky as a bright green fireball over the Golden Horseshoe region of Southern Ontario, Canada.
The discovery was the first predicted meteor to fall over a densely populated area, but the rock posed no danger. It was about one meter (3.3 feet) in diameter when it entered Earth’s atmosphere, making it the smallest asteroid observed before entering the atmosphere to date.
Here it became a flaming bolide and crashed, falling to Earth as smaller pieces that fell mostly into water of Lake Ontario. Most parts of the meteorite that can be found must be small pieces of debris; scientists hope to retrieve some of them to study the asteroid further.
The previous five asteroids discovered before the impact were 2008 TC3, which was about 4 meters in diameter; 2014 AA, at 3 meters; 2018 LA, also three meters across; 2019 MO at 6 meters across; and a little earlier this year 2022 EB5, which was about 2 meters in diameter.
The discovery of 2022 WJ1 and the global coordination that followed it is a wonderful testament to how sensitive technology has grown and the magnificence of human collaboration to better understand the treacherous space rocks.
And, of course, these observations represent a rare opportunity to study what happens to asteroids when they enter Earth’s atmosphere.
“This fireball is particularly important because the main meteoroid was observed telescopically before it hit the atmosphere. This makes it a rare opportunity to link telescope data on an asteroid to its atmospheric decay behavior to gain insight into its internal structure.” said astronomer and physicist Peter Brown from the University of Western Ontario.
“This remarkable event will provide clues about composition and strength that, combined with telescope measurements, will inform our understanding of how small asteroids break up in the atmosphere, important knowledge for protecting the planet.”
Debris from 2022 WJ1 should be dark, with a thin and fresh fusion crust and a grayer stony interior. Scientists request that any suspicious fragments be reported to Royal Ontario Museum.