Scientists catch a glimpse of the incoming asteroid just hours before it impacts: ScienceAlert

For the sixth time in recorded history, astronomers managed to glimpse an asteroid before it slammed into Earth.

On November 19, 2022, nearly four hours before impact, the Catalina Sky Survey detected an asteroid named 2022 WJ1 on an incoming trajectory. A network of telescopes and scientists sprang into action and calculated exactly when and where on the globe the asteroid would fall.

This is excellent news. 2022 WY1 was too small to do any serious damage, but its detection 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 might can cause any damage.

While space is mostly space, it also contains a lot of non-space. Near Earth, those non-space are usually asteroids orbiting the Sun in such a way that they come close 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 almost all of them large enough to pose a significant threat, studied them and determined that none of them will be close enough in the next century will come to be a threat.

Still, it’s good to keep abreast of what’s buzzing in the space around us, and to hone our skills at finding sneaky stones that remind you to make 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. It continued to track the object, taking four images that astronomers could use to confirm its detection, and reported it to the IAU Minor Planet Center at 05:38 UTC.

Those four images were enough to calculate the asteroid’s trajectory through the sky, with multiple impact monitoring programs finding that the rock had a roughly 20 percent chance of coming down somewhere on the North American continent.

Follow-up observations allowed scientists to refine their measurements by specifying a time and a location. Bang on schedule, 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 discovery was the first ever predicted meteor to fall over a densely populated area, but the rock posed no danger. It was about a meter (3.3 feet) in diameter when it entered Earth’s atmosphere, making it the smallest asteroid yet observed before entering the atmosphere.

Here it turned into a flaming bolide and shattered, falling to the earth as smaller pieces that usually fell into the waters of Lake Ontario. Most findable bits of the meteorite should be small pieces of debris; scientists hope to retrieve some of them to study the asteroid further.

The previous five asteroids detected before impact were 2008’s TC3, which measured about 4 meters across; 2014 AA, 3 meters wide; 2018 LA, also three meters wide; 2019 MO at 6 meters in diameter; and, just earlier this year, 2022 EB5, which was about 2 meters across.

The detection of 2022 WY1, 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 space rogues.

And of course, those observations provide a rare opportunity to study what happens to asteroids as they enter Earth’s atmosphere.

“This fireball is particularly important because the original meteoroid was observed telescopically before it reached the atmosphere. This makes it a rare opportunity to link telescopic data from an asteroid to its breakup in the atmosphere to gain insight into its internal structure,” said astronomer. and University of Western Ontario physicist Peter Brown.

“This remarkable event will provide clues to composition and strength that, when combined with telescopic measurements, will give us insight into how small asteroids break up in the atmosphere, important knowledge for planetary defense.”

Debris from 2022 WY1 should be dark, with a thin and fresh fusion crust and a grayer stony interior. Scientists are asking that all suspicious fragments be reported to the Royal Ontario Museum.

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