Orbital View: Crater in Córdoba Province

Editor’s Note: This article previously appeared in a different format as part of The Atlantic’s Notes section, retired in 2021.

The distorted landscape looks as if the impact is pulling the fields inward:

Rio Cuarto crater scars the Argentinian landscape.

A photo posted by Kjell Lindgren (@astro_kjell) on

The crater is part of a series predominantly formed in a very rare pattern:

The [Río Cuarto] craters were thought to be due to a grazing impact of a set of objects at a very low angle, which calculations show to be a rare occurrence. Most impacts will strike at an angle of 45 degrees to the horizontal or greater, and the impact craters will always be close to circular, since the shock wave that results from the impact propagates symmetrically.

A grazing impact, however, will form an elliptical crater, with sprays of debris that look like butterfly wings. This has been confirmed by high-velocity guns used for impact experiments, and more recently by computer simulations. On impact, the object may shed chunks of itself that fly further downrange to perform secondary impacts.

Models of the Río Cuarto event suggest that the object struck at an angle of no more than 15 degrees from the horizontal, with the impact itself having 10 times more explosive energy than the Barringer Crater event and 30 times more than the Tunguska event [citation needed]. Although the age of the craters has not yet been determined precisely, it is believed they are about 10,000 years old, placing them at the start of the Holocene.

(See all Orbital Views here)