On November 19, asteroid 2022 WJ1 turned one among many small asteroids to hit Earth, however solely the sixth we have ever seen come. For the second time this yr, humanity predicted an asteroid influence. The ~1 m rock precipitated no harm and burned into the sky above Toronto as a hanging fireball. The detection, warning and advance observations of this asteroid illustrate our quickly growing potential to warn of asteroid impacts, nonetheless small.
The primary detection of asteroid 2022 WJ1 got here from the Catalina Sky Survey – one of many main tasks devoted to the invention and follow-up of near-Earth objects (NEOs) – at 04:53 UTC (05:53 CET) on November 19, 2022, just below 4 hours earlier than the influence.
The brand new asteroid was first imaged by Catalina’s 1.5 m Mt. Lemmon telescope, and when 4 observations had been made it was reported to the Minor Planet Heart (MPC), 38 minutes after the primary detection, at 05:31 UTC.
These 4 observations had been sufficient to map the asteroid’s path within the sky, and inside minutes of this “astrometry” being revealed, ESA’s personal inside monitoring program reported that the item had a ~20% likelihood of an Earth influence, presumably hitting someplace in North America in the course of the the following two to 3 hours. A couple of minutes later, different efficiency monitoring applications additionally despatched alerts describing an analogous state of affairs.
After the potential influence bulletins, observers at Catalina and elsewhere in the USA acquired follow-up observations of the brand new asteroid. Lower than half-hour from the primary launch, the influence was confirmed with wonderful precision: the small asteroid, most likely lower than a meter in diameter, would hit someplace between Lake Erie and Lake Ontario, close to the US-Canada border, round 08:27 UTC ( 09:27 CET).
At precisely the anticipated time, a ~1-m asteroid hit the ambiance and have become an excellent fireball over the anticipated location. Learn extra about this occasion on ESA’s Close to-Earth Object Coordination Heart (NEOCC) internet portal.
Asteroid influence: what’s the danger?
Because of the manner the photo voltaic system was fashioned, small objects are within the majority when it comes to their complete inhabitants. It’s estimated that there are 40-50 million small asteroids and “solely” 1,000 of the most important, large “planet killers”. The remaining fall someplace in between.
We presently know of greater than 1.1 million asteroids, though many extra are on the market. Of these found, about 30,600 journey in orbits that convey them near Earth’s personal. These are “near-earth asteroids” (NEAs).
The reassuring information is that the majority large asteroids have been discovered – greater than 95% – and none are of concern for the following hundred years. Astronomers tirelessly seek for each single one.
Small, meter-sized asteroids hit Earth each two weeks. They contribute to our understanding of asteroid populations, fireballs and their make-up, however they don’t seem to be a excessive precedence in terms of planetary protection as a result of they pose no actual hazard.
The objects we’re most involved about are these “gold cap asteroids” which might be large enough to do harm in the event that they hit, and there are sufficient of them on the market that we all know they may sooner or later. The notorious Chelyabinsk influence in February 2013 and the Tunguska influence in June 1908 fall into this class, and in terms of discovering these asteroids, there may be nonetheless numerous work to be completed.
That is why ESA’s Planetary Protection Workplace is planning new ground-based telescopes and house missions to enhance our potential to detect asteroids, sending the Hera mission to the Dimorphos asteroid hit by NASA’s DART mission to check asteroid deflection, in addition to working with the worldwide group to organize for the state of affairs the place a bigger asteroid is found on a collision course.
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