Who discovered that meteorites come from space?
No single person: the German physicist Ernst Chladni argued in 1794 that they came from space, chemist Edward Howard showed in 1802 that they share a distinctive chemistry, and Jean-Baptiste Biot's 1803 investigation of the L'Aigle fall convinced the scientific world.
For much of the 18th century, scientists were deeply sceptical about stones falling from the sky. Reports from farmers and villagers were often dismissed as superstition, or explained as rocks struck by lightning or thrown up by volcanoes. The breakthrough came in a remarkable burst of work around 1800.
In 1794 the German physicist Ernst Chladni published a short book arguing that falling stones and masses of iron, including a famous iron-and-crystal mass from Siberia described by the naturalist Peter Simon Pallas, came from beyond the Earth and were linked to fireballs. Many colleagues ridiculed the idea. But nature seemed to take his side: in the following years stones fell near Siena in Italy in 1794, at Wold Cottage in Yorkshire in 1795, and near Benares in India in 1798.
Next came the chemistry. In 1802 the English chemist Edward Charles Howard, working with the mineralogist Jacques-Louis de Bournon, analysed several of these stones and showed that they shared a similar make-up quite unlike local rocks, including grains of metal containing nickel. That shared fingerprint suggested a common, unusual origin. The howardites, one of the meteorite groups linked to the asteroid Vesta, are named in Howard's honour.
The final blow to doubt fell in 1803, when thousands of stones rained down near L'Aigle in Normandy. The French Academy of Sciences sent the young physicist Jean-Baptiste Biot, who interviewed witnesses, mapped where the stones lay and concluded that they really had fallen from the sky. His careful report persuaded most scientists. Exactly where in space meteorites came from took much longer to work out: their link to asteroids was only firmly established in the 20th century, when cameras recorded the paths of falling meteorites and traced them back to the asteroid belt.