Post by Hand of Fate on Aug 19, 2009 23:13:23 GMT -8
99942 Apophis is a near-Earth asteroid that caused a brief period of concern in December 2004 because initial observations indicated a relatively large probability (up to 2.7%) that it would strike the Earth in 2029. Additional observations provided improved predictions that eliminated the possibility of an impact on Earth or the Moon in 2029. However there remained a possibility that during the 2029 close encounter with Earth, Apophis would pass through a gravitational keyhole, a precise region in space no more than about 400 meters across, that would set up a future impact on April 13, 2036. This possibility kept the asteroid at Level 1 on the Torino impact hazard scale until August 2006. It broke the record for the highest level on the Torino Scale, being, for only a short time, a level 4, before it was lowered.
Source: Wiki
Path of Risk, above.
For the sake of our story, however, Apophis hits the earth and causes the following damage:
NASA initially estimated the energy that Apophis would have released if it struck Earth as the equivalent of 1480 megatons of TNT. A later, more refined NASA estimate was 880 megatons. The 1883 eruption of Krakatoa was the equivalent of roughly 200 megatons.
The impact of Apophis fragments near the countries of Colombia and Venezuela, had more than 10 million casualties. The impact of fragments several thousand miles off the West Coast of the US produced a devastating tsunami and wipe out cities from Anchorage, AK straight down the seaboard to the Gulf of Mexico.
These impacts caused the following effects:
Large amounts of regolith (and perhaps shattered bedrock) into the atmosphere
Firestorms in heavily forested areas, throwing up large amounts of smoke and ash into the atmosphere.
The latter scenario was the more dangerous, as the lighter particles from the fire would take weeks or months to fall back to earth, and could be distributed by jet streams around the world, making the cooling a global event.
The mechanism of impact winter is very similar to that which occurs after nuclear war, leading to nuclear winter.
Volcanoes also eject large amounts of opaque material into the higher parts of the atmosphere, with large explosions such as the 1991 explosion of Mount Pinatubo and the much larger 1783 Laki eruption, having measurable effects on the world's climate.
The simultaneous eruption of a number of large volcanoes, a catastrophic volcanic winter scenario, is another proposed mechanism for extinction events, and several earthquakes and volcanoes were set off by the impact event.
In short, for a year or more humanity would be lost in several weeks of falling ash, and then a winter of a year or more, before survivors could claw their way out into a vastly changed bio-sphere.
Source: Wiki
Path of Risk, above.
For the sake of our story, however, Apophis hits the earth and causes the following damage:
NASA initially estimated the energy that Apophis would have released if it struck Earth as the equivalent of 1480 megatons of TNT. A later, more refined NASA estimate was 880 megatons. The 1883 eruption of Krakatoa was the equivalent of roughly 200 megatons.
The impact of Apophis fragments near the countries of Colombia and Venezuela, had more than 10 million casualties. The impact of fragments several thousand miles off the West Coast of the US produced a devastating tsunami and wipe out cities from Anchorage, AK straight down the seaboard to the Gulf of Mexico.
These impacts caused the following effects:
Large amounts of regolith (and perhaps shattered bedrock) into the atmosphere
Firestorms in heavily forested areas, throwing up large amounts of smoke and ash into the atmosphere.
The latter scenario was the more dangerous, as the lighter particles from the fire would take weeks or months to fall back to earth, and could be distributed by jet streams around the world, making the cooling a global event.
The mechanism of impact winter is very similar to that which occurs after nuclear war, leading to nuclear winter.
Volcanoes also eject large amounts of opaque material into the higher parts of the atmosphere, with large explosions such as the 1991 explosion of Mount Pinatubo and the much larger 1783 Laki eruption, having measurable effects on the world's climate.
The simultaneous eruption of a number of large volcanoes, a catastrophic volcanic winter scenario, is another proposed mechanism for extinction events, and several earthquakes and volcanoes were set off by the impact event.
In short, for a year or more humanity would be lost in several weeks of falling ash, and then a winter of a year or more, before survivors could claw their way out into a vastly changed bio-sphere.
