Dutch instruments track rare asteroid explosion over Normandy

Sensitive Dutch instruments detected the explosion of a small asteroid over France in February 2023, providing unprecedented data on the behavior of cosmic impacts, the Royal Netherlands Meteorological Institute (KNMI) stated.

Asteroid 2023 CX1, roughly one meter in diameter and weighing 600 to 800 kilograms, was discovered on February 12, 2023, just a day before it entered Earth’s atmosphere at more than 52,000 kilometers per hour. The asteroid disintegrated over Normandy at an altitude of approximately 28 kilometers, producing a massive blast. The explosion released an estimated 0.03 kilotons of energy.

Witnesses near Le Havre reported seeing a large "fireball" in the sky. The explosion generated infrasound waves—sound at frequencies below 20 hertz, inaudible to the human ear but detectable by specialized instruments.

These waves were recorded across multiple stations in the Netherlands, including De Bilt, and as far away as Russia, 5,500 kilometers from the blast site. “This is the first time an asteroid’s entry and fragmentation have been so comprehensively tracked—from its discovery in space to the recovery of fragments on Earth,” the KNMI said.

More than 100 fragments of the asteroid were recovered in France and studied by an international team of nearly 100 scientists, including researchers from KNMI and Delft University of Technology. The findings were published September 17 in Nature Astronomy.