February 14, 2016

Review: Many Skies by Arthur Upgren

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It’s a question we all find ourselves asking on occasion. What would our skies look like if things were a little bit different? It’s a fun thought experiment to play; add a Moon here or a Sun there and see what happens. While the night sky may be beautiful, it’s somewhat of a cruel joke that we live out our earthbound existence from but a single vantage point. Perhaps this mediocre position in time and space is why we’re here at all; having lots of active and exotic objects nearby such as supernovae and black holes may not bode well for life. [Read more...]

27.10.09: Exploring Shiva Crater.

A profile of Shiva Crater. (Credit: Sankar Chatterjee/Texas Tech University).

A profile of Shiva Crater. (Credit: Sankar Chatterjee/Texas Tech University).

Move over, Chicxulub; we may have a new contender in the realm of cosmic extinction events. Recently, paleontologist Sankar Chatterjee of Texas Tech University has dubbed a ring shaped subsurface structure off of the western coast of India Shiva crater. If Chaterjee is correct, it would be one of the largest impact basins on Earth recorded, at a diameter of about 500 km wide. Aptly named after the Hindu goddess of destruction, Shiva would have been caused by an asteroid or comet of about 40 km in diameter. Chaterjee has been following data accrued by decades of off-shore oil drilling projects in the area; the existence of iridium deposits suggests a calamity of cosmic origin. Rare on Earth but common on asteroids, the element iridium was considered a “smoking gun” in dating the aforementioned K-T extinction event of about 65 million years ago. Tantalizingly, the Shiva Crater event also seems to date from the same era. This raises the question; could a hail of cometary debris have been common in that far gone time? Bodies without rapid erosion, such as our Moon or Mars, should show evidence of impacts dating from around this epoch. Of course, the crater hypothesis is not without its critics…the area surrounding the Indian subcontinent is very geologically active as it pushes under the plates of the Asian continent. In particular, an area known as the Deccan Traps extends to the edge of Shiva and was very active during the Cretaceous period. Also, Shiva appears to have rock from the Earth’s underlining mantle exposed, again tantalizing evidence for a past cataclysm… this area of our own near space begs for further exploration!