With its big hole mysteriously appearing on its roof on November 20, the little red Clio from Illkirch, near Strasbourg, intrigued the media. Faced with the "impact" of "50 centimetres" in diameter which "went through the roof, the underbody and the fuel tank of the vehicle", the firefighters, cautious, put forward the possibility of a "fall of a stellar body". A two-centimetre-wide "gravel" found near the vehicle was handed over to police for analysis.
Although scientists had already expressed serious doubts about the hypothesis, the analyses carried out by the School and Observatory of Earth Sciences (EOST) are categorical: this piece of rock "is not a fragment of a meteorite". "After an initial observation with a binocular magnifying glass, the rock [...] does not exhibit any of the characteristics of meteorites," the school said on its website, citing the "absence of fusion crust" and a composition that does not match.
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A terrestrial rock
The "scanning electron microscopy" analysis identified the piece of rock as a "sandstone," a sedimentary rock on Earth. It is composed of "multiple crystals of various natures (quartz, orthose, albite, pyrite), the whole, partially covered by crystallized filaments of hydrocarbons (bitumen or diesel)".
The school also notes that the "seismological data from the permanent stations in the region" did not record a "clear signal that could be linked to a meteorite entry into the atmosphere".
A block of ice?
But what could have caused such damage? Among the hypotheses raised shortly after the incident was also the possibility that a block of ice had fallen on the vehicle as a result of an aircraft flying aloft.
On this point, the EOST does not come to conclusions but stresses that the probability of a meteorite falling on a car ("one chance in a hundred billion each year") is "much lower than that of a block of ice falling from an aircraft". The latter can form when aircraft "pass through clouds with ice crystals" or "during the occasional emptying of aircraft toilets".