Airblast scars on Venus

Article Abstract:

Radar images of Venus's surface taken by the Magellan spacecraft revealed many dark margins that are not surrounded by an associated meteoric impact crater. These craterless dark patches may have been generated by shock waves from meteorites that exploded in the thick Venusian atmosphere before they could reach the surface. This scenario resembles what is thought to have happened on Jun 30, 1908 when a comet or meteorite devastated 2,000 square kilometers near the Tunguska river in Siberia but left no crater. Such an event would be quite likely on Venus where the atmosphere is 50 times denser than Earth's.

Research, Observations, Surface (Geology), Venus (Planet), Magellan (Space probe), Radar astronomy

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Around and around we go

Article Abstract:

Scientists differ on the size of the Chicxulub crater located in the Yucatan, now associated with extinctions at the Cretaceous-Tertiary (K/T) boundary. V.L. Sharpton and colleagues have estimated the size of the crater to be twice as big as was previously estimated. A.R. Hildebrand and colleagues using the same data as Sharpton have contested that the previous diameter measurement of 180 km is accurate. The controversy over the crater's size is caused because the crater has deteriorated and the mechanisms of this change are not completely understood.

Analysis, Measurement, Meteorological research

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Meteor Crater formed by low-velocity impact

Article Abstract:

Meteor Crater in Arizona, the first terrestrial structure to be widely recognized as a meteorite impact scar, displayed that the surface-impact velocity of the iron meteorite that created the meteor was only 12 km s(super -1). The meteor created by a dispersed swarm of low-velocity iron fragments is also consistent with the recovery of large numbers of small, unmelted iron-meteorite fragments near the crater.

United States, Arizona, Discovery and exploration, Impact craters, Meteor Crater (Arizona)

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