Il primo frammento era stato trovato oltre 30 anni fa da una contadina nei campi di Twann, nel canton Berna, mentre oggi i pezzi recuperati di quello che è stato battezzato il meteorite di Twannberg sono circa 600 e i ricercatori dell'Università di Berna, guidati da Beda Hofmann, sono riusciti a ricostruire la sua storia, al centro di un'esposizione al Museo di storia naturale del cantone.
La pietra spaziale, rara per quanto riguarda la sua composizione ferrosa, aveva un diametro di almeno sei metri ed è esplosa mentre precipitava verso la superficie terrestre più di 100'000 anni fa dopo aver vagato per oltre 240 milioni di anni nel sistema solare.
Proprio l'età dei frammenti rendono eccezionale il ritrovamento: in climi temperati i resti dei meteoriti tendono a degradarsi più rapidamente e i più antichi vengono normalmente trovati nei deserti o in Antartide.
ATS/sf
Dal TG20:
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