Volunteers in front of a fragment of 2023 CX1. FRIPON/Vigie-Ciel
A collaboration between astronomers and enthusiasts has made it possible to find a piece of the fireball that lit up the Norman sky at the start of the week.
“This is exceptional ! I am really moved by the idea that the meteorite I have in my pocket was still in space a few days ago, before falling here, in Normandy.”, says Sylvain Bouley, researcher in the Geosciences laboratory at the University of Paris-Saclay. The scientist is the co-founder of the Fripon and Vigie-Ciel initiatives, which made it possible to find on the ground part of the racing car which lit up the Norman sky during the night from Sunday to Monday, at 3:59 am.
Seven hours earlier a Hungarian astronomer, Krisztian Sarneczky, had discovered the asteroid in the sky, initially named Sar2267, before finally receiving the name 2023 CX1 in the NASA reference database. Immediately, this small rocky body with an estimated size of one meter in diameter attracts attention, because it will hit the Earth! The first calculations predict a fall at sea, in the English Channel, near the Normandy coast, and give little hope of finding fragments on the ground. Due to the small size of the object, its arrival on our planet does not present any serious risk for the populations.
A fragment found. FRIPON/Vigie-Ciel
On Monday morning, just before 4 am, a handful of enthusiasts, in France, but also in England, Belgium, Germany and the Netherlands, await the entry of the object into the atmosphere. And at the scheduled time, to the minute, they observe a magnificent spectacle: a shooting star arriving from the west disintegrates into a magnificent ball of fire illuminating the night sky very briefly. This is the bolide, or meteor, caused by the disintegration of the asteroid. “The luminous flash that we observe at this moment is not an explosion, it is just the fragmentation of the initial object, a rocky object about one meter in diameter, into a multitude of fragments which increase brutally the luminosity », explains François Colas, astronomer at the Paris Observatory, present in Normandy since Monday to participate in the search for meteorites. « In the same way, a handful of sand thrown in the air in front of the sun will be more luminous than the same quantity of sand held in the hand. »
But beyond the spectacle, the first videos above all allow scientists to precisely determine the trajectory of the object. The fragmentation took place at an altitude of 25 km, above the Normandy coast, which means that debris could have fallen to the ground, on a line which goes from the coast (between Fécamp and Dieppe) to a few kilometers inland. The asteroid, with an estimated initial mass of around 1.5 tonnes, entered the atmosphere at a speed close to 50,000 km/h! « With videos taken at very different places, by triangulation, we can determine with good precision the trajectory of the meteor. Then just extend the trajectory to know where it will fall », explains François Colas.
For this unique event, the videos taken by amateurs are added to the Fripon scientific surveillance network: a hundred cameras covering the entire sky above France in order to be able to record such events. As soon as a ball of fire is recorded in the French sky, the Vigie-Ciel network takes over. « This participatory science program led by the National Museum of Natural History brings together scientists and amateurs to search for meteorites in the field »explains Asma Steinhausser, project coordinator at the Museum.
From Monday, the first volunteers, researchers and enthusiasts, met in Normandy to try to find fragments of 2023 CX1. And, after a few days, their perseverance paid off. Wednesday, at 4:47 p.m., Loïs Leblanc, an 18-year-old art history student from Perche with her parents to participate in research, spots a dark pebble, stuck in the loose soil of a field in the town of Saint -Pierre-le-Viger. The pebble, weighing around one hundred grams, is covered with a fusion crust characteristic of the brutal heating when entering the dense layers of the atmosphere.
« This is only the third time in history that a fragment has been found on the ground of an object detected in space before its arrival on Earth. », enthuses Sylvain Bouley. And the first time in France, of course! For the scientist, it is also the consecration of the efforts made for a decade to set up the Fripon/Vigie-Ciel project. And the quest does not end there, research continues on the ground in Normandy, hoping that their search party, or someone in the area, can find other fragments of the asteroid.
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