Hi, Larry, List, The Melosh model says this is a "once-in-a-lifetime" event, meaning once in 4 billion years. That however would not include that first 500 or 600 million years, the Hadean Era.
At some point, this and bigger events must have happened to the Earth. One has only to look at the Moon and its visible record. For every basin we see there, picture 18 just like it on the Earth. I suspect the rock-melting calculations of the model are flawed at this scale. Punching though (or deep enough into) the crust would not let anything be buried. Instead, the release of pressure on the high-pressure high-temperature interior would cause it to melt, boil and explode outward. It would expose the near-molten rock at 30 km down, which is at a pressure of 150,000 pounds per square inch, to the vacuum of deep space (for all practical purposes, our atmosphere doesn't count). Gravity need not be taken into account in the gas laws, but in a planetary body it is the source of all interior pressure, right down to the 52,500,000 pounds per square inch found at the center of the Earth. I suspect that puncturing the thin but very rigid skin of a planet would produce not merely basalt flooding, but initially an immense "fire-fountain" type of volcano that would blast material right out through the atmosphere. What a sight that would be! I suspect you'd want to watch from high orbit or maybe the Moon, though. Sterling K. Webb ------------------------------------------------------------------------------- Original Message ----- From: <[email protected]>
To: "Sterling K. Webb" <[email protected]>Cc: <[email protected]>; <[email protected]>; "Meteorite List" <[email protected]>
Sent: Wednesday, July 01, 2009 11:17 PM Subject: Re: [meteorite-list] Another awful meteorite-related TV event
Hi Sterling: Sounds more reasonable, if destroying everything is reasonable. Any idea how often these occur? This is 5 times the diameter of either Sudbury or Vredefort and these are more than a billion years old.Maybe this is big enough to punch through the mantle and bury itself inmagma. LarryHi, Larry, List, Yes, I am WRONG! However, my mistake was not the one you hypothesized. The Wikipedia gives mass in kilograms and I reduced the quantity by 1000 to convert it to tons (10^18 kg = 10^15 metric tons), correctly. No, it was density. I think in grams per cubic centimeter when I think density. Water = 1.0, rock = 2.5, and so forth. The training is strong; one thinks in specific density. But the online Calculator wants kilograms per cubic meter, where water = 1000, rock = 2500, and so forth. So I calculated the impact of a 100 kilometer diameter SNOWFLAKE ! One with a specific density of about 0.022, a little fat for a snowflake, actually... So, if you ever want to know what impact a really big snowflake would have, you've got it now. The actual figures? The energy is 304,000,000,000 megatons. The crater is 1240 km (770 miles) across and would be 2500 meters deep before it fills with melt. The impact would melt 2,000,000 CUBIC MILES of the Earth's crust, and the melt zone extends to a depth of 35 kilometers, which in some places would take it down into the mantle itself, and it would certainly rebound and produce basalt flooding of incomprehensible magnitude, likely enough to flood and re-surface an entire continent. The "crater" would be a complex multi-ringed basin about the same size as the Moon's Mare Imbrium! Big enough for you now? This is a continent destroyer. The shock of the impact, would be a world-wide Richter Scale 12.3, strong enough to kill all animal life. The wind at the antipodeal point to the impact would be 385 mph. At just a quarter of the way around the planet (10,000 km away), the winds would be 835 mph. The fireball of the impact would be over 300 kilometers in diameter (190 miles) and it would be visible for 5570 kilometers (3500 miles). The thermal flux would be 53 times brighter than the Sun and everything organic within the line of sight would combust. This fireball would persist for nearly 8 hours (7 hours 42 minutes) before cooling enough to collapse. The shock wave there (3500 miles away) would be over 2000 mph, or about Mach 3. Major extinction event, clearly. I can't speak to the roaches; no one knows what it takes to wipe them out, if indeed it's even possible. Still, at the worst, the sulfur-eating thermophiles in the deep vents would survive just fine, fat and happy, and they could start this evolution thing all over again, something they've probably had to do before, as the universal inclusion of the 16S rna ribosome in most living things attests to. A little better? Sterling K. Webb -------------------------------------------------------------------------------- ----- Original Message ----- From: <[email protected]> To: "Sterling K. Webb" <[email protected]> Cc: <[email protected]>; "Meteorite List" <[email protected]> Sent: Wednesday, July 01, 2009 9:03 PMSubject: Re: [meteorite-list] Another awful meteorite-related TV eventHi Sterling:I will admit that, at first, I got the wrong asteroid (though now moreinteresting composition) and I am never one to say you are wrong, but... YOU ARE WRONG!!!!! Sorry, that felt good!If you go by Wikipedia, you lost 3 zeros 1x10^18 bit 1X10^15. It wouldbehad to believe that a 100-km diameter object (give or take) would makea 40-km hole in the ground unless it was going real slow and hit a really hard surface.Somthing that big would probably make a hole 1000 km or so across (atleast), which would make it a bad day even for the roaches. Oh, did I forget to mention: You are wrong! It is a rare day that I get to say that to you Sterling, sorry. LarryHi, List, To quantify that impact, I went and ran the numbers through the online Impact Calculator that uses the Jay Melosh model: http://www.lpl.arizona.edu/impacteffects/ If 216 Kleopatra is 220 km x 100 km x 100 km, its volume is 17,278,875.96 km^3 or a total of (take a deep breath) 1,778,875,960,000,000 m^3. That's 1.7 quadrillion cubic meters and its mass would be at least 3.5 quadrillion metric tons. (Dogbone and Potato asteroids have lots of voids and a high porosity.) No, wait! It's 114 Kassandra? Get your Apocalypses straight, people! The volume of 114 Kassandra is less than Kleopatra: 523,598,644,700,000 cubic meters. The mass of 114 Kassandra, if rock, has to be at a minimum of 1,500,000,000,000,000 tons, although some sources say it's only 1,000,000,000,000,000. That big number is a Quadrillion tons, in case you want to know. OK, it's Kassandra! Smaller, lighter. Really puny. I gave it an intercept velocity of 47 km/s, a little slow for an eccentric orbit from the Asteroid Zone, and an incidence angle of 45 degrees. The energy of the collision is 1.20 x 10^24 Joules or 268,000,000 MegaTons TNT. The Calculator says "The average interval between impacts of this size somewhere on Earth during the last 4 billion years is 360,000,000 years." That energy is the equivalent of an explosion created by detonating a nuclear arsenal 1800 times bigger than the entire nuclear arsenals of all the nations of the world -- at once. The final crater diameter is 39.5 km or 24.5 miles; its final depth is 0.895 km or 0.556 miles. That seems oddly small for something so big. Why is that? Well, the Calculator says that the final crater is replaced by a large, circular melt province. The volume of the target melted or vaporized is 6410 cubic km or 1540 cubic miles. The melt volume is 2.87 times the crater volume If 114 Kassandra hit Los Angeles, you'd probably be alright (for a while) if you were in New York City (or Boston). You'd be alright, that is, if you can withstand the shock wave which, at that distance, would have a wind velocity of 140 mph, or a hurricane-level Force Nine Gale on the Beaufort Scale. Where I live, it'll be over 205 mph. The real problem, I suspect, is in the vaporization of a substantial percentage of that "melt province." If 10% of the rock vaporized, or 1.5 trillion tons of rock vapor would be distributed very quickly through the atmosphere at temperatures of more than 2000 degrees F. That quantity of rock vapor amounts to about 20,000 tons of rock vapor per square mile of the Earth's surface. The Impact Calculator does not discuss the contribution of the asteroid to the mass of rock vapor. I would suggest that at least 1% of it would survive as "mere" rock vapor (instead of plasma) -- that's an additional ten trillion tons, raising the distribution to 110,000 tons of rock vapor per square mile of the Earth's surface (about 190,000,000 square miles). I suggest a very study, fireproofed umbrella would be a good idea if you plan on going out... This is an impact at least 30 to 50 times worse than the Chicxulub Impact which, it has been suggested, burned most of the vegetation off the planet with its rock vapor plume. 114 Kassandra's effect could only be characterized as the "Krispy Kritter" impact. It sounds like a a lousy environment in which to stage a mini-series. But... That's Entertainment! Sterling K. Webb ----------------------------------------------------------------------- ------ Original Message ----- From: <[email protected]> To: <[email protected]> Cc: <[email protected]> Sent: Wednesday, July 01, 2009 12:03 PM Subject: Re: [meteorite-list] Another awful meteorite-related TV event If Kleopatra were to hit the Earth (at least that is what I get out of the main page), we would be in big trouble. For those of you who do not remember, 216 Kleopatra, thanks to radar observations, looks very much like a big dog bone, 220 kilometers long and 100 kilometers across. Larry ----------------------------------------------------------------------------------------------- ----- Original Message ----- From: "Darren Garrison" <[email protected]> To: "Meteorite List" <[email protected]> Sent: Wednesday, July 01, 2009 11:38 AM Subject: [meteorite-list] Another awful meteorite-related TV eventhttp://www.movieweb.com/news/NEn3LrswY8Zyro ______________________________________________ http://www.meteoritecentral.com Meteorite-list mailing list [email protected] http://six.pairlist.net/mailman/listinfo/meteorite-list______________________________________________ http://www.meteoritecentral.com Meteorite-list mailing list [email protected] http://six.pairlist.net/mailman/listinfo/meteorite-list
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