Vigarano: the story of a meteorite

Sat, 24 Jul 2010 11:31:28 +0000
Num. 32

One of the most important meteorites in the world fell in the Ferrara area one hundred years ago.

Ugo Martini, municipal secretary of Vigarano Mainarda, referred to the event as follows in March 1910: "On the night of 22 January 1910, at 21:30, the Bovini family, who live in the Saracca farm house, owned by Mr. Michele Cariani in Vigarano Pieve, a hamlet in the Municipality of Vigarano Mainarda (Ferrara), was awakened by a strong explosion that was like a mortar explosion. The night was stormy, it was snowing, and a few women were spinning in the kitchen. The ladies claim that they saw a streak of lightening at the same time as the explosion. They got scared, and called the men who were sleeping. The men explored the outside of th e house with lanterns. They saw something three metres south east of the house, on the ground lightly covered with snow, and immediately confirmed that the hole had been made recently. Naturally they sank a shovel into the hole, and hit a solid, cold body, which they took out". That is how the story of the Vigarano meteorite started one hundred years ago; a meteorite prized by collectors and experts all over the world. The Vigarano meteorite fell on 22 January 1910 at about 21:30, a little over a hundred metres from the Vigarano Pieve church, west of Ferrara. The main body of 11.5 kg was found immediately after the fall, while a few weeks later a second body of 4.5 kg was found a few hundred metres from the main one. The Vig arano meteorite, along with the Renazzo meteorite (which fell in 1824) are the only two carbonaceous chondrites to have been discovered in Italy, both falling in the Province of Ferrara, and just a little over 20 km apart. Eyewitness accounts mention seeing a very bright reddish-green trail, followed by two strong explosions, with a hissing sound in between. The main body (11.5 kg) fell three metres south east of the Saracca farm house, owned by Michele Cariani. It formed a crater about 70 cm deep and about 1.5 m in diameter, melting the snow around it. The secondary body (4.5 kg) was found in February 1910, about 700 m to t he north east, in the Vignola farm, owned by Quirino Morandi. The meteorites are known as the "Cariani meteorite" (11.5 kg) and the "Morandi meteorite" (4.5 kg). The Vigarano meteorite has been subject to ongoing detailed petrological and geochemical studies, and has given rise to about a hundred scientific articles. It is a carbonaceous chondrite, i.e. a type of meteorite that has not undergone much alteration; generally an assemblage of metals subject to strong heat will tend to form composites, but this doesn't happen in chondrites. They contain minerals that form at both high and low temperatures, therefore lending themselves to the study of proto-planetary disk material. Another reason this can be done is because the Vigarano meteorite is older than our planet (4. 6 billion years old, i.e. a few tens of millions of years older than Earth). Carbonaceous chondrites contain more water and volatile substances than other meteorites; they are defined as carbonaceous because they contain organic compounds that could be considered to be the precursors of life; in fact some are rich in amino acids. In addition, an extraordinary correspondence has been found to exist between the sun's composition, inferred from its spectrum, and the composition of the carbonaceous chondrites.