1,500-ton meteorite "passes NASA's eye", explodes as strong as 10 atomic bombs

A meteorite the size of a school bus exploded in Earth's atmosphere on December 18, 2018, with the impact energy of 10 atomic bombs.Live ScienceAccording to NASA, this is the second largest meteorite explosion since the agency began tracking them 30 years ago, behind only the fireball that exploded over the city of Chelyabinsk, Russia in February 2013.

However, almost no one saw the explosion happen, most likely because the meteor exploded over the Bering Sea, a cold part of the Pacific Ocean, located between Russia and Alaska, kilometers away from any inhabited area. NASA learned about the explosion through the US Air Force.

The meteor exploded about 25 km above sea level.

US Air Force missile surveillance satellites were among the first to detect the explosion. Debris from the explosion was also picked up by ultrasonic detectors around the world, which measure low-frequency sound waves inaudible to the human ear. This allowed scientists to collect enough data to draw some basic conclusions about the meteorite.

According to NASA, the meteorite weighed about 1,500 tons, was about 10 meters in diameter, and flew through the atmosphere at a speed of 115,200 km/h before exploding. The explosion occurred 25 kilometers above sea level and released energy equivalent to 173 kilotons of TNT, 10 times the energy of the atomic bomb dropped on Hiroshima in World War II. The 19-meter-wide Chelyabinsk meteorite flew over Russia and was recorded by many drivers. The shock wave of the explosion injured more than 1,200 people.

Astronomical monitoring organizations around the world failed to detect the approaching asteroid due to its small size. Alan Fitzsimmons, an astronomer at Queen's University in Belfast, Northern Ireland, said most modern telescopes are designed to detect objects a few hundred meters in diameter or more. Therefore, objects this small are easy to miss.