The sixth asteroid impact we saw coming
November 19, asteroid 2022 WJ1 became one of many small asteroids to hit Earth, but only the sixth we ever saw coming. For second time this year, mankind predicted an asteroid impact. The ~1m rock did no damage and burned up in the sky above Toronto as an impact fireball. The discovery, warning and previous observations of this asteroid illustrate our rapidly growing ability to warn of asteroid impacts, however small.
The first discovery of asteroid 2022 WJ1 came from Catalina Sky Survey – one of the major projects dedicated to detecting and tracking near-Earth objects (NEOs) – at 04:53 UTC (05:53 CET) on November 19, 2022, just under four hours before impact.
The new asteroid was first imaged by the Catalina 1.5-m Mount Lemmon Telescopeand after four observations have been made it is reported The center of the minor planets (MPC), 38 minutes after initial detection, at 05:31 UTC.
These four observations were enough to map the asteroid’s path across the sky, and within minutes of this ‘astrometry’ being released, ESA’s own internal tracking software reported that the object had a ~20% chance of hitting Earth , possibly hitting somewhere. in North America in the next two to three hours. Minutes later, other influencer monitoring programs also sent alerts citing a similar scenario.
After being notified of the potential impact, observers in Catalina and elsewhere across the US received follow-up sightings of the new asteroid. Less than 30 minutes after the initial trigger, the impact was confirmed with excellent precision: a small asteroid, probably less than a meter in diameter, should have hit somewhere between Lake Erie and Lake Ontario, near the US-Canada border, around 08:27 UTC (09:27 CET).
At exactly the predicted time, the ~1 m asteroid hit the atmosphere becoming a bright fireball above the expected location. Learn more about this event at ESA’s Near Earth Object Coordination Center (NEOCC) web portal.
Asteroid impact: what’s the risk?
Because of the way the solar system formed, small objects are the majority in terms of their total population. There are an estimated 40-50 million small asteroids and “only” 1,000 of the largest, giant “planet killers”. The rest is somewhere in between.
We currently know of more than 1.1 million asteroids, although there are many more. Of those discovered, approx 30 600 they travel in an orbit that brings them close to Earth’s. These are ‘near earth asteroids’ (NEAs).
The encouraging news is that almost all giant asteroids have been found – more than 95% – and none are of concern for the next hundred years. Astronomers tirelessly search for every last one.
Small meter-sized asteroids hit Earth every few weeks. They contribute to our understanding of asteroid populations, fireballs and their composition, but are not a high priority when it comes to this Planetary defense because they do not pose a real danger.
The objects we’re most concerned about are those ‘Goldilocks asteroids’ that are big enough to do damage if they hit, and there are enough of them that we know they will at some point. Infamous Chelyabinsk influence in February 2013 i Tunguska influence June 1908 fall into this category, and when it comes to discovering these asteroids, there is still a lot of work to be done.
That’s why ESA Office of Planetary Defense is planning new ground-based telescopes and space missions to improve our ability to detect asteroids by sending Hera mission to the asteroid Dimorphos that hit NASA DART mission test asteroid deflection, as well as work with the international community to prepare for a scenario where a larger asteroid is detected on a collision course.
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