On the first morning of the new year, Andrew Koch was working on his computer in Pittsburgh when a sound of thunder rumbled through his house.
The images had in fact captured what astronomers later concluded was a meteor exploding over western Pennsylvania around 11:20 a.m. Saturday, producing a burst of energy equivalent to 30 tons of DTT. The bolide – a meteor brighter than Venus – would have weighed around 1,000 pounds, measured one meter in diameter and streaked through the atmosphere at 45,000 mph, NASA said Tuesday.
A meteor of this size plunges into the Earth’s atmosphere every three or four days. But because most of the planet is covered in water, the majority of these meteors fall where no one sees or hears them, said Bill Cooke, who heads NASA’s office of meteoroid environments. If it hadn’t been for Saturday’s cloudiness, Pennsylvania residents might have been in for quite a show.
“If it had been clear, there would have been something 100 times brighter than the full moon moving north to south in the Pittsburgh sky,” Cooke said. “That would have been pretty cool to see.”
Meteors have entertained people in Michigan, Puerto Rico and elsewhere for the past few years. The most recent fireball has drawn joking comparisons to the new movie ‘Don’t Look Up,’ which features astronomers trying to warn the world of a comet heading for Earth and satirizes indifference to climate change.
“Netflix’s marketing budget for Don’t Look Up is out of control” one person tweeted in response to the New Year’s fireball.
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Scientists launched their investigation into the cause of the boom by ruling out unlikely causes. The sound was audible over a wide geographic area, which ruled out local phenomena such as fireworks. The National Weather Service had recorded no thunder or lightning.
Then someone from the National Oceanic and Atmospheric Administration noticed the light recorded by an optical instrument on the GOES-16 satellite, which monitors the eastern part of North America. At the time of the noise, the satellite’s geostationary Lightning Mapper recorded four lightning bolts moving from north to south. Lightning moves more randomly than that, Cooke said – but the pattern was consistent with a meteor crashing and producing flares.
Scientists then cross-referenced the discovery with logs from one of the many infrasound stations placed around the world to monitor compliance with nuclear test ban treaties. When meteors travel about 20 miles from Earth, they separate and produce low frequency infrasound inaudible to humans. Sound travels downward, Cooke said, shaking the ground and shaking homes.
When scientists saw that an infrasound station had recorded noise around the same time as the Geostationary Lightning Mapper, the mystery seemed to be solved.
“It left no doubt that what was over western Pennsylvania on New Year’s Day was a crashing bolide,” Cooke said.
While meteor explosions tend to raise fears of falling fiery rocks, Cooke said damage from the pressure of the explosion is a much more realistic concern. Films about meteor explosions, he added, are generally not accurate.
But Cooke said he couldn’t speak to specific footage from “Don’t Look Up,” which is streaming on Netflix. He didn’t see it.
“Rocks falling from the sky is hard work,” Cooke said. “So I’m waiting for it to come on cable.”
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