For only the sixth time in recorded history, astronomers have managed to spot an asteroid before it hits Earth.
On November 19, 2022, nearly four hours before impact, the Catalina Sky Survey discovered an asteroid named 2022 WJ1 on an inbound trajectory. A network of telescopes and scientists sprang into action, calculating precisely when and where on the globe the asteroid would fall.
That’s excellent news. 2022 WJ1 was too small to cause serious damage, but its detection shows that global asteroid monitoring techniques are improving, giving us a better chance of protecting ourselves from falling space rocks – the biggest ones that could actually do damage. damage.
Although space is mostly space, it also contains a lot of non-space. In the vicinity of the Earth, this non-space consists mainly of asteroids which orbit the Sun in such a way as to bring them closer to Earth’s orbit. We call them near-Earth asteroids, and at the time of writing 30,656 of them have been cataloged.
Most of these asteroids are actually quite small, and scientists are confident that we’ve found nearly every one large enough to pose a significant danger, studied them, and determined that none of them will come close enough. over the next century to be a threat.
Still, it’s good to stay aware of what’s buzzing in the space around us and to hone our abilities to find sneaky rocks thinking about making a grand entrance.
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The detection of 2022 WJ1 was made at 04:53 UTC on November 19, 2022, by the Mount Lemmon Observatory, part of the Catalina Network. He continued to monitor the object, taking four images that allowed astronomers to confirm the detection, and report it to the IAU Minor Planet Center at 05:38 UTC.
These four images were enough to calculate the asteroid’s trajectory across the sky, with several impact monitoring programs finding that the rock had about a 20% chance of falling somewhere on the North American continent.
Follow-up observations allowed scientists to refine their measurements, giving a time and location. Bang as expected, at 08:27 UTC, 2022 WJ1 was seen crossing the sky as a bright green fireball, over the Golden Horseshoe region of southern Ontario, Canada.
The find was the first meteor ever predicted to fall on a densely populated area, but the rock was not a hazard. It was about one meter (3.3 feet) in diameter when it entered Earth’s atmosphere, making it the smallest asteroid ever observed before entering the atmosphere to date.
Here it transformed into a fiery bolide and shattered, falling to Earth in small pieces that mostly fell into the water of Lake Ontario. Most of the locatable pieces of the meteorite should be small bits of debris; scientists hope to recover some of them to study the asteroid further.
The previous five asteroids detected before impact were 2008 TC3, which was about 4 meters in diameter; 2014 AA, 3 meters in diameter; 2018 LA, also three meters in diameter; 2019 MO at 6 meters in diameter; and, just earlier this year, 2022 EB5, which measured around 2 meters in diameter.
The detection of 2022 WJ1 and the global coordination that followed is a wonderful testament to the sensitivity of technology and the magnificence of human cooperation in better understanding rogue 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 significant because the parent meteoroid was observed telescopically before it hit the atmosphere. This makes it a rare opportunity to relate an asteroid’s telescopic data to its breakup behavior in the atmosphere. atmosphere to better understand its internal structure,” said the astronomer. and physicist Peter Brown of the University of Western Ontario.
“This remarkable event will provide clues to composition and strength that, combined with telescopic measurements, will inform our understanding of how small asteroids break up in the atmosphere, important knowledge for planetary defense.”
Debris from 2022 WJ1 is expected to be dark, with a thin, cool fusion crust, and a grayer stony interior. Scientists ask that any suspicious fragments be reported to the Royal Ontario Museum.
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