- August 16, 2023 - Planétarium : Experience
For a long time, in the West, people didn't believe that meteorites fell from the sky. It took a daring scientist and a meteorite shower in the town of L'Aigle in 1803 to change our perception of those celestial objects.
Thunderstone
Meteorite falls have always intrigued humans. Some saw bad omens in them, others saw divine signs. Despite the many eyewitnesses, Western scholars refused to believe the farmers who claimed to have seen stones falling from the sky. In the 18th century, those stones were even classified in the category of "thunderstones. " These could be found among the diverse objects that were exhibited in the curio cabinets of the time.
Lavoisier's analysis
In the wake of a fall of stones in the French commune of Lucé in 1768, the Academy of Sciences asked three chemists, including the later-to-be-famous Antoine Lavoisier, to analyze the stones.
But methods of analysis in that period were rudimentary. Observation through magnifying glasses would show the presence of grains of metal that chemists confused with pyrite. In truth, these were bits of iron and nickel, a mineral unknown at the time. The analytical report, presented by Lavoisier, would conclude that the stones didn't fall from the sky, but instead that what was involved was a stone rich in pyrite that had been struck by lightning.
The boldness of Chladni
In April 1794, the German scholar Ernst Chladni published a book in which he laid out his observations on several types of rocks and falls of stones. He argued that stones, arriving from outer space, can fall from the sky and form fireballs as they pass through the Earth's atmosphere.
He went even further, claiming that these stones are fragments of a planet that failed to form.
Those highly daring hypotheses, well ahead of their time, were rather badly received by scholars of the period.
The L'Aigle fall
Chladni's ideas would nonetheless be confirmed by a meteorite shower on April 26, 1803, over the town of L'Aigle, in France. Around 1 p. m. local time, more than 3,000 fragments of stones rained down on the area. Inhabitants heard two noises similar to cannon shots, followed by rolling thunder. Stones then fell from the sky, a spectacle that frightened more than a few people.
Biot's inquiry
The minister of the interior at that time wanted to shed light on these events, and entrusted the inquiry to the young astronomer Jean-Baptiste Biot.
Biot made his way to L'Aigle on June 26. On the road he questioned all the travelers about the fall of stones. Once on the scene he meticulously explored the environs and collected many other eyewitness observations. Thus he could draw up the first meteorite dispersal map.
The historic report
Biot's report was presented to the members of the Institut de France on July 18, 1803. The document, entitled Account of a journey made in the department of the Orne, in order to ascertain the reality of a meteor observed in L'Aigle on 6 floréal an 11, is today famous.
In it he presents "moral proof" of the fall of meteorites in the form of witness statements from a wide-reaching social diversity. Those witnesses had no interest in lying about the events.
Biot also determined that there was no foundry, factory, mine or volcano where the meteorites could have originated. For Biot, the fall of stones at L'Aigle in 1803 could only be explained by accepting that they fell from the sky. He believed nevertheless that the stones came from the Moon.
The quality of Biot's report would definitively bring to an end the debate about the extraterrestrial origin of meteorites. From that moment on, those celestial stones acquired the status of objects of incontestable scientific interest.
