A meteor traveling 20 miles per second exploded between Russia and Alaska with the power of 10 World War II-era atomic bombs -- and nobody noticed.
The 32-foot-diameter space rock, estimated to weigh 1,400 tons, blew up Dec. 18 over the Bering Sea, New Scientist reported.
The meteor exploded with a force equal to 173 kilotons of TNT, or about 10 times as much as the atomic bomb dropped on Hiroshima, Japan, at the end of World War II, a NASA chart of fireballs shows.
Scientists only recently pinpointed the blast -- the third-largest known meteor explosion -- by triangulating readings from infrasound stations, which pick up low-frequency noises that humans can’t hear, New Scientist says.
The U.S. Air Force also alerted NASA about the explosion after picking it up on military satellites, BBC News reported.
A Japanese weather satellite picked up what appears to be smoke in the upper atmosphere from the explosion, said Simon Proud of the University of Oxford, who posted some of the photos to Twitter.
“Some colour views of the #meteor that flew over the North Pacific in December 2018, taken by Japan’s #Himawari satellite,” Proud wrote. “The meteor is really clear here -- bright orange fireball against the blue + white background!”
The explosion went largely undetected by the public or press while scientists collected data because of the remote location, said Kelly Fast, manager of NASA’s near-Earth objects observations program.