It sometimes happens that witnesses observe a meteor in the sky and a few seconds later witness the fall of a meteorite a few tens or hundreds of kilometers away. At least five times during the 20th century, the point of impact could be located and fragments of meteorites were collected, the weight of which varied between a few grams and nearly a ton.
This kind of event remains exceptional given the small quantity of large meteorites falling on Earth (less than one per year in an inhabited place). In all other cases the researchers must gather clues to corroborate the extraterrestrial hypothesis of the structure they have discovered. This is where a real scientific investigation begins.
In some cases, Richat for example, the circular depression is so symmetrical that for decades scientists have considered it to be the result of the impact of a meteorite until a field study confirms that it s ‘is an eroded geological formation, it is true particularly symmetrical and well preserved.
Geologists from the University of New Brunswick in Canada tell us that at least six clues allow us to authenticate a meteorite impact, based both on macroscopic morphometric and stratigraphic analyzes and microscopic analyzes of samples taken from the site. These clues are also good indicators to discover the possible.