* Astronomy

The asteroid presumed to have wiped out the dinosaurs struck the Earth with such force that carbon deep in the Earth's crust liquefied, rocketed skyward, and formed tiny airborne beads that blanketed the planet, say scientists from the U.S., U.K., Italy, and New Zealand in this month's Geology.
The beads, known to geologists as carbon cenospheres, cannot be formed through the combustion of plant matter, contradicting a hypothesis that the cenospheres are the charred remains of an Earth on fire. If confirmed, the discovery suggests environmental circumstances accompanying the 65-million-year-old extinction event were slightly less dramatic than previously thought.

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The meteorite linked to the mass extinction of dinosaurs and other life forms 65 million years ago was four to six kilometres in diameter. Thats the conclusion of a team of Hawaii University researchers who have evolved a mechanism to measure the size of meteorites that have rammed into earth over millennia.
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Title: Importance of pre-impact crustal structure for the asymmetry of the Chicxulub impact crater
Authors: Sean P. S. Gulick, Penny J. Barton, Gail L. Christeson, Joanna V. Morgan, Matthew McDonald, Keren Mendoza-Cervantes, Zulmacristina F. Pearson, Anusha Surendra, Jaime Urrutia-Fucugauchi, Peggy M. Vermeesch & Mike R. Warner

Impact craters are observed on the surfaces of all rocky planets and satellites in our Solar System; some impacts on Earth, such as the Cretaceous/Tertiary one that formed the Chicxulub impact crater, have been implicated in mass extinctions. The direction and angle of the impactor its trajectoryis an important determinant of the severity of the consequent environmental damage, both in the downrange direction (direction bolide travels) and in the amount of material that enters the plume of material vaporised on impact. The trajectory of the Chicxulub impact has previously been inferred largely from asymmetries in the gravity anomalies over the crater. Here, we use seismic data to image the Chicxulub crater in three dimensions and demonstrate that the strong asymmetry of its subsurface correlates with significant pre-existing undulations on the end-Cretaceous continental shelf that was the site of this impact. These results suggest that for rocky planets, geological and geomorphological heterogeneities at the target site may play an important role in determining impact crater structure, in addition to impact trajectories. In those cases where heterogeneous targets are inferred, deciphering impact trajectories from final crater geometries alone may be difficult and require further data such as the distribution of ejecta.

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