RE: Earth may have underground 'ocean' three times that on surface
June 27, 2014 at 12:00 pm
(This post was last modified: June 27, 2014 at 12:25 pm by Anomalocaris.)
The amount of dumb that you kept from the idiocy comet that hit you leaves you with no room for diamonds and gold.
The accretion of the earth from protoplanetary disk was mostly completed in less than 100 million years, most likely within 1-10 million years, 4.6 billion years ago. 99.9% of impacts earth will likely ever experience happened in those 1-10 million years. Most of the remaining 0.1% impacts that earth was yet to experience at the end of its formation likely occurred in subsequently in a single brief episode, called late heavy bombardment, around 3.9 billion years ago.
The fact that rate of impact by comets and asteroids were many orders of magnitude higher at the beginning of solar system's history than now is well attested by the ages of craters on the moon, mars, and mercury. It is also indirectly attested by geological record of the earth.
Current rate of cometary impact on earth is estimated at one dino killer sized comet every roughly 100 million years, 1 Haley sized comet (15 miles) every roughly 2 billion years. During earth's first few million years the impact rate would have been roughly 1 Haley sized comet every few years. During late heavy bombardment it would have been 1 Haley sized compet every few thousand to tens of thousands of years.
A Haley sized impact would end human civilization and cause a mass extinction event that would dwarf the one which killed the dinosaurs and ended the Cretaceous, and probably kill most if not all mammals, including humans.
The accretion of the earth from protoplanetary disk was mostly completed in less than 100 million years, most likely within 1-10 million years, 4.6 billion years ago. 99.9% of impacts earth will likely ever experience happened in those 1-10 million years. Most of the remaining 0.1% impacts that earth was yet to experience at the end of its formation likely occurred in subsequently in a single brief episode, called late heavy bombardment, around 3.9 billion years ago.
The fact that rate of impact by comets and asteroids were many orders of magnitude higher at the beginning of solar system's history than now is well attested by the ages of craters on the moon, mars, and mercury. It is also indirectly attested by geological record of the earth.
Current rate of cometary impact on earth is estimated at one dino killer sized comet every roughly 100 million years, 1 Haley sized comet (15 miles) every roughly 2 billion years. During earth's first few million years the impact rate would have been roughly 1 Haley sized comet every few years. During late heavy bombardment it would have been 1 Haley sized compet every few thousand to tens of thousands of years.
A Haley sized impact would end human civilization and cause a mass extinction event that would dwarf the one which killed the dinosaurs and ended the Cretaceous, and probably kill most if not all mammals, including humans.
