May 14, 1864 (a Saturday)

A fragment of the Orgueil meteorite.

On this date, a carbonaceous chondrite disintegrated and fell in fragments near the French town of Orgueil. One specimen was immediately examined by the French scientist S. Cloëz, who commented that its content “would seem to indicate the existence of organized substances in celestial bodies.” Subsequently, several eminent chemists of the time, including Gabriel-Auguste Dubrée and Marcellin Berthelot, analyzed samples and confirmed the existence of organic materials in the rock. However, hopes of discovering actual living matter in the meteorite were dashed by the experiments of Louis Pasteur, as recounted by Carl Sagan:

[He] caused a special drill to be constructed, which, he hoped, would remove samples from the interior of the meteorite without contaminating them with microorganisms from outside. Using sterile techniques, Pasteur inoculated an organic medium to search for growth of any indigenous microorganisms which the meteorite interior might contain. The results were negative, and have relevance today: Pasteur extracted his sample shortly after the fall of the meteorite, and was, of course, a very careful experimentalist.

A fragment of the Ivuna meteorite (Tanzania, Africa, 1938).

Virtually all meteorites scientists have studied are former parts of asteroids. However, recent determination of the amino acid signatures within the Orgueil meteorite and Ivuna meteorite suggest that these compounds were likely synthesized from components such as hydrogen cyanide, which have been recently observed in the comets Hale-Bopp and Hyakutake. This suggests that the organic material in Orgueil and Ivuna is the product of reactions that once took place in the nucleus of a comet, which, if true, would make these meteorites the first to be identified as having come from a cometary nucleus. This would add to the evidence that the amino acids that helped generate life on Earth may have been delivered by meteorites that were derived from the remnants of comets.

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