This Asteroid Could Have Wiped Out a City. Scientists Almost Missed It.

A large asteroid crater filled with muddy water, surrounded by forrest.
Lonar Crater and its saline lake in India’s Maharashtra state, the remnant of an asteroid impact about 50,000 years ago.
ALEX OGLE/Getty Images

Last week, an asteroid whizzed past Earth, passing us at less than one-fifth of the distance to the moon. Good thing it didn’t come any closer, because scientists had no clue it was coming until it would have been too late to defend ourselves, had we been in its path.

Researchers in the United States and Brazil identified it just a week before it passed Earth. The deceivingly dull-sounding Asteroid 2019 OK came “out of nowhere,” Australian astronomy professor Michael Brown told the Washington Post. Scientists hadn’t been tracking 2019 OK and provided the public with information about its size and whereabouts just hours before it hurtled by at 54,000 miles per hour.

There are a couple of reasons why it went undetected for so long. This asteroid has an elliptical orbit that took it past Mars and within the orbit of Venus, ultimately meaning that it spent little time near Earth, visible to scientists.

Moreover, 2019 OK wasn’t big enough to demand attention. Scientists are generally good at detecting massive asteroids like the one that wiped out the dinosaurs—they’ve spotted 90 percent of the sort that are a half-mile wide or larger—but 2019 was only as big as a large boulder. The fact that it came from the direction of the sun, blinding astronomers to its approach, didn’t help.

Had Asteroid 2019 OK crashed into the Earth, it would have done serious damage.
Professor Allan Duffy, a scientist at the Royal Institute of Australia, told the Sydney Morning Herald that “it would have hit with over 30 times the energy of the atomic blast at Hiroshima.” That makes it deserving of a spot among asteroids with a Hollywood-quality nickname: the “city-killers.”

Scientists are well aware of the “city-killer” threat. A few months ago, Jane C. Hu reported on a weeklong conference where astronomers debated what to do if they found out that a space rock was hurtling toward the Earth. It’s far from being an implausible scenario. Prior to the 2019 OK threat, there were three close flybys occurring between 73,000 and 274,000 miles away. And in 2013, a meteor struck Chelyabinsk, Russia, injuring at least 1,200 people, according to the Washington Post. The scientists’ conclusion at the recent conference? They would likely launch spacecraft armed with defense weapons, possibly nukes, to fend off the looming asteroid. Still, questions lingered about who would call the shots if this happened—would it be a designated country, or intergalactic committee who deems it appropriate to deploy the weapons? As Hu reported, that decision was “outside the purview of the conference, but it seems like piece of the puzzle that law and politics experts should figure out long before we’re faced with an actual asteroid threat.”

Now, 2019 OK’s brief but alarming appearance is sure to nudge that discussion forward. According to Duffy, this should be a wake-up call: “It is a clear and present danger.”

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