September 26, 2017

AstroEvent: A Very Looong Annular Eclipse!

Animation of the Annular Eclipse on January 15th, 2010.

Animation of the Annular Eclipse on January 15th, 2010. (Credit: NASA/A.T. Sinclair).

          One of the more unique celestial events on the calendar for 2010 occurs on Friday, January 15th; an annular eclipse of the Sun, and the longest for the millennium! An annular solar eclipse occurs when the moon is at or near apogee (its most distant point from the Earth) and/or the Earth is at or near perihelion (its closest approach to the Sun)… these happened on January 17th and January 2nd respectively, setting us up for a visually large Sun and correspondingly small Moon, small enough that it won’t completely cover the Sun’s disk.   The maximum possible duration for an annular eclipse is 12 minutes and 24 seconds and the actual maximum for this eclipse is 11 minutes and 7.7 seconds, which occurs off of the southwestern coast of the Indian subcontinent. [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!

Review: Cyberabad Days by Ian McDonald.

Near future Sci-fi is an especially cherished genre. Via such classics as 2001: A Space Odyssey, we can eagerly await such things as living on the Moon, or by reading such tales as 1984, we can shudder at Orwell’s anti-utopian world, and hopefully heed its warning. Cyberabad Days: Return to India of 2047 by Ian McDonald, serves up both in heaping doses.

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