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Location, Location, Location

September 27, 2012

Between the Oort cloud, the Kuiper Belt, various collections of asteroids and random rocks, over four billion years there are a great many potential impactors wandering about as any casual telescopic glance at the Moon will show. By most standards, Mercury and Venus have been pounded – and likely Mars as well. There would have to have been some really HUGE impacts at one time to account for the current motions of Venus and Uranus. Still, even though a great many rocks are in our orbital plane, more or less, the Earth moves pretty swiftly, and is a relative small target in all the vastness of space. Besides the mass (size and density) and velocity of the impactor it also matters when and where it strikes. As intrepid simulators of the Eltanin impact (2.5 million years ago between Chile and Antarctica) have discovered, a deepwater collision is significantly different from a dry land collision. Of course, there’s the immediate area damage (a crater) as well as pyroclastic flows, molten ejecta and so on for dozens or perhaps hundreds of miles from the crater, but the real game changer is planetary or at least hemispheric atmosphere alteration. It is clear that major (many VEI=5 and all VEI=6) volcanic eruptions can cause an impact on climate for several years. Many of the impacts listed below ejected far more debris into the stratosphere than even all-time all-star volcanic events like Toba. The problems highlighted below are lack of precise timings in when objects hit, and whether events were close enough in time to reinforce atmospheric trauma.

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From → Impact craters

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