Uncle Ron 1,492 Posted February 7, 2020 Share Posted February 7, 2020 https://www.geologyin.com/2016/10/worlds-second-largest-meteorite.html?fbclid=IwAR3Aee7Olih5d9Khs4E4TNi3JPz8o9FUTwozAEyin0iRYBP3Zg9WFPHPqHA 8 1 Quote Link to post Share on other sites
steelguy 51 Posted February 8, 2020 Share Posted February 8, 2020 thanks for posting, enjoyable read! 1 Quote Link to post Share on other sites
Mikestang 933 Posted February 10, 2020 Share Posted February 10, 2020 Can you imagine the fireball that created the Campo del Cielo strewn field? It must have been an amazing sight. 2 Quote Link to post Share on other sites
Morlock 1,797 Posted February 10, 2020 Share Posted February 10, 2020 36 minutes ago, Mikestang said: Can you imagine the fireball that created the Campo del Cielo strewn field? It must have been an amazing sight. Is there a crater someplace or has it filled in over time? If so, do they know where it was? Quote Link to post Share on other sites
Mikestang 933 Posted February 10, 2020 Share Posted February 10, 2020 No crater or they wouldn't be finding all the huge irons, as they would have vaporized on impact to create a crater. Quote Link to post Share on other sites
GotAU? 123 Posted February 10, 2020 Share Posted February 10, 2020 (edited) 15 minutes ago, Mikestang said: No crater or they wouldn't be finding all the huge irons, as they would have vaporized on impact to create a crater. The article said there were at least 26 craters there. Edited February 10, 2020 by GotAU? Updated Quote Link to post Share on other sites
Mikestang 933 Posted February 10, 2020 Share Posted February 10, 2020 (edited) Oh right, I was thinking about a different iron. That event would have been something to witness... Edited February 10, 2020 by Mikestang 1 Quote Link to post Share on other sites
Uncle Ron 1,492 Posted February 11, 2020 Author Share Posted February 11, 2020 I'm happy I got a nice 27 gram sample of the Campo del Cielo ... One of my big mistakes was selling my entire collection of the Wickenburg Meteorite...1,000 grams for $2,500...Since I know the strewnfield I figure I could find more, but getting all crippled up has stopped me from searching... Cheers, Unc Quote Link to post Share on other sites
Morlock 1,797 Posted February 11, 2020 Share Posted February 11, 2020 18 hours ago, Mikestang said: Oh right, I was thinking about a different iron. That event would have been something to witness... The Hoba meteorite is the largest one in the world at 60 tons. How is it that fall never created a crater while others that were smaller did? Quote Link to post Share on other sites
GotAU? 123 Posted February 11, 2020 Share Posted February 11, 2020 3 minutes ago, Morlock said: The Hoba meteorite is the largest one in the world at 60 tons. How is it that fall never created a crater while others that were smaller did? Impact velocity, entry and orbital vectors of both Earth and the meteorite, all that stuff? Quote Link to post Share on other sites
Morlock 1,797 Posted February 11, 2020 Share Posted February 11, 2020 6 minutes ago, GotAU? said: Impact velocity, entry and orbital vectors of both Earth and the meteorite, all that stuff? So a 60 ton chunk of iron nickel just fell out of the sky and plopped down on the ground without a crater? Quote Link to post Share on other sites
GotAU? 123 Posted February 11, 2020 Share Posted February 11, 2020 Its old also, and was in sand. Perhaps the desert wind and sand covered it. What I meant is that if a meteorite hits in the same direction Earth is orbiting, vs opposite of it, then the speed will be much different. Also the composition of the country rock and the meteor would have an affect, along with the age of the impact. But then, there’s always the alien effect variable... ;) Quote Link to post Share on other sites
Bedrock Bob 4,224 Posted February 11, 2020 Share Posted February 11, 2020 5 hours ago, GotAU? said: What I meant is that if a meteorite hits in the same direction Earth is orbiting, vs opposite of it, then the speed will be much different. Fun fact. The speed at which an object collides with the earth's atmosphere may be greater relative to a point on earth. And the impact to The atmosphere may be slightly greater against the spin of the globe. BUT The explosion in the air that brings the object to terminal velocity will be greater. The speed at which an object hits the ground would not be. An object that cannot slow to terminal velocity will vaporize. So any solid chunks left after bolide are all obeying the laws of physics and the crater they form is based on their mass, angle and speed. Their speed of impact would not be affected by the earth's rotation at all. They all start at cosmic speeds and slow to terminal velocity before impact no matter which direction they are flying. Otherwise they detonate and never hit the surface. Leastwise that is the way I understand it. Quote Link to post Share on other sites
LukeJ 2,161 Posted February 11, 2020 Share Posted February 11, 2020 Is it possible for the angle of entry to be so slight that the object 'skips' and eventually 'rolls' to a stop? Luke Quote Link to post Share on other sites
Mikestang 933 Posted February 11, 2020 Share Posted February 11, 2020 (edited) Objects regularly skip off the atmosphere, but since there is no other force is space to act on them they just keep going and don't stop. One of the most famous is the great daytime fireball of 1972. Edited February 11, 2020 by Mikestang 1 Quote Link to post Share on other sites
Bedrock Bob 4,224 Posted February 11, 2020 Share Posted February 11, 2020 7 minutes ago, Mikestang said: Objects regularly skip off the atmosphere, but since there is no other force is space to act on them they just keep going and don't stop. One of the most famous is the great daytime fireball of 1972. No doubt the earth's atmosphere slowed that one quite a bit. And changed its trajectory/orbit. Chaotic chunks of stuff rattling around out there until they smash into something. If that isn't cool then nothing is. About as real as it gets. 2 Quote Link to post Share on other sites
LukeJ 2,161 Posted February 12, 2020 Share Posted February 12, 2020 6 hours ago, Mikestang said: Objects regularly skip off the atmosphere, but since there is no other force is space to act on them they just keep going and don't stop. One of the most famous is the great daytime fireball of 1972. What about Space Force? I heard that's a thing now. Actually, I was thinking about objects entering the atmosphere and skipping like a 'stone on a pond'. A possible way to reduce the impact energy and not leave a crater near the location site. Just a thought.... Luke 1 Quote Link to post Share on other sites
Morlock 1,797 Posted February 12, 2020 Share Posted February 12, 2020 (edited) 10 hours ago, LukeJ said: What about Space Force? I heard that's a thing now. Yep. Space force is a thing now and led by our own very beloved dear leader aka..flash trump. Anyone know the weight of that meteorite that created the Meteor Crater in Arizona? Are their any educated guesses out there? The Old Woman Meteorite is another large fall that didn't seem to leave a crater. It was found in a ravine on the side of a mountain. Edited February 12, 2020 by Morlock Quote Link to post Share on other sites
hardtimehermit 526 Posted February 12, 2020 Share Posted February 12, 2020 Canyon Diablo was 30 metric tons of iron before it began to vaporize. Quote Link to post Share on other sites
Morlock 1,797 Posted February 12, 2020 Share Posted February 12, 2020 14 minutes ago, hardtimehermit said: Canyon Diablo was 30 metric tons of iron before it began to vaporize. So a 30 ton meteorite left the huge crater we all know about in Arizona and a 60 ton meteorite left no crater? Quote Link to post Share on other sites
Bedrock Bob 4,224 Posted February 12, 2020 Share Posted February 12, 2020 1 hour ago, Morlock said: So a 30 ton meteorite left the huge crater we all know about in Arizona and a 60 ton meteorite left no crater? Exactly. Because it detonated in the air before it reached the surface. It could not shed the required velocity and (mostly) vaporized. As the case with Tonguska. Once again. Only the fragments that slow to terminal velocity hit the surface. Only the explosions close enough to the surface displace material and leave craters. Objects that are too big/too fast detonate high in the atmosphere and do not leave craters. And those that do leave craters are subject to erosion and tectonics. So most craters on earth have been erased. Earth had (relatively) as many craters as the moon at one time. But the forces at work on earth have erased them. Our (relatively) heavy atmosphere and erosionary forces erase craters. Only the largest and most recent remain. There is a sweet spot in size/speed that allow an object to penetrate our atmosphere. Too big or too fast and they vaporize. Too small/ too slow and they burn up high above the surface. Just right and they impact or bolide close enough to displace material and form a crater. Any mass that remains after slowing to terminal velocity falls to earth. The crater is formed by impact. Any explosion close enough to the surface to displace material forms a crater from explosion. A bomb that falls unexploded makes a little crater formed by its mass/speed. A bomb that explodes just above/at the surface forms a larger crater by the energy released from the explosion. A bomb that explodes high in the atmosphere leaves no crater at all. Big craters like Barringer are formed by explosion. Little craters like the one in Peru a few years ago are caused by mass impacting. It can be assumed the 60 tonne Campo slowed to terminal velocity before impact and left a crater. It just was erased by the forces of nature in the past 50,000 years like so many other terrestrial features have in that same time period. 2 Quote Link to post Share on other sites
billpeters 391 Posted February 12, 2020 Share Posted February 12, 2020 (edited) 4 hours ago, hardtimehermit said: Canyon Diablo was 30 metric tons of iron before it began to vaporize. The actual mass of Canyon Diablo before it struck the Earth was 8,578,642,193 pounds, or about 4 million metric tonnes. The incoming bolide was 160 feet across with the average iron nickel mass of 500+ lbs per cubic foot, based on actual calculation of its components. The estimated recoverable mass of Canyon Diablo is a mere 30 metric tons, or 0.00077% of what hit the Earth. 20 hours ago, LukeJ said: Is it possible for the angle of entry to be so slight that the object 'skips' and eventually 'rolls' to a stop? No, it it not possible. A massive bolide coming in at a slight angle which still impacts the ground would still be slowed to a steep decent by the dense atmosphere while maintaining some percent of it cosmic velocity. It it was so large to barely be slowed it would still make a large, deep circular crater upon impact. Bolides can graze the upper atmosphere or skip off provided they are not slowed by drag too much. On 2/11/2020 at 8:08 AM, Morlock said: The Hoba meteorite is the largest one in the world at 60 tons. How is it that fall never created a crater while others that were smaller did? The Hoba Meteorite when found in 1920 was buried completely. It has been estimated to have fallen nearly 80,000 years ago and likely made a crater that was worn away from higher ground and then covered up naturally with dirt and sand over the millennia. 21 hours ago, Bedrock Bob said: They all start at cosmic speeds and slow to terminal velocity before impact no matter which direction they are flying. Otherwise they detonate and never hit the surface. Not correct. Essentially all meteorites first ablate (detonate) to varying degrees before slowing to terminal velocity. Only extremely massive meteorites whose main mass remains car sized or above will be able to maintain some of its cosmic speed before impact and not fully slow to terminal velocity. What this means for meteorite hunters is that no matter what angle the meteorite enters the atmosphere it will drop from a steep 65% angle to nearly vertically at a slow speed its last ten miles of descent. Weather radar returns of the falling rocks will be nearly directly above the recovery zone. Happy hunting, billpeters Edited February 12, 2020 by billpeters 4 Quote Link to post Share on other sites
Bedrock Bob 4,224 Posted February 12, 2020 Share Posted February 12, 2020 4 hours ago, billpeters said: Not correct. Essentially all meteorites first ablate (detonate) to varying degrees before slowing to terminal velocity. Only extremely massive meteorites whose main mass remains car sized or above will be able to maintain some of its cosmic speed before impact and not fully slow to terminal velocity. What this means for meteorite hunters is that no matter what angle the meteorite enters the atmosphere it will drop from a steep 65% angle to nearly vertically at a slow speed its last ten miles of descent. Weather radar returns of the falling rocks will be nearly directly above the recovery zone. Happy hunting, billpeters I think we are on the same page. My point here was that the direction the object comes in in relation to the spin of the earth makes little to no difference in the size of the crater or the velocity upon impact. Speed decay (or retention) is certainly influenced by size. So larger objects do hit faster. They retain their speed longer and give it up more reluctantly. Those are the "sweet spot" I mentioned above. But too large or too fast results in complete destruction. Anything left after that explosion falls to earth at terminal velocity. And yes! The angle the objects hit are nearly vertical if not absolutely vertical. Things fall in a parabolic arc and the end of that arc is very steep. Objects don't hit the earth at much of an angle. That is a huge misconception and incorrect assumption that many meteorite guys make. It is a great point of discussion and I thank you for bringing it up. The angle of impact with the atmosphere is certainly a factor in the angle of impact With the surface but entry bends that steeply. Just as the speed of impact with the atmosphere is a factor but makes only a small difference in surface impact speed. The size and composition of the object makes as much or more difference than any other factor whether the object will fall or detonate or a little of both. Speed and angle are certainly factors in the ballistics but mass is the overwhelmingly biggest factor for sure. Bigger objects will retain both speed and direction better. But anything that hits the ground is slowed to at (or as near as possible to) terminal velocity. And anything that hits the ground falls at (or very nearly) vertically. Quote Link to post Share on other sites
Bedrock Bob 4,224 Posted February 12, 2020 Share Posted February 12, 2020 What an awesome meteorite thread! It sure beats what has been happening here. Thank you guys! 1 Quote Link to post Share on other sites
GotAU? 123 Posted February 12, 2020 Share Posted February 12, 2020 On 2/11/2020 at 7:57 AM, GotAU? said: Its old also, and was in sand. Perhaps the desert wind and sand covered it. What I meant is that if a meteorite hits in the same direction Earth is orbiting, vs opposite of it, then the speed will be much different. Also the composition of the country rock and the meteor would have an affect, along with the age of the impact. But then, there’s always the alien effect variable... ;) Originally, I commented on how the speed of the earth may affect crater size, depending on the vectors of the collision, but I was misunderstood. I was talking about the orbital velocity of the earth which is over 100,000 km/h, not the spin of the Earth, which is much slower. Quote Link to post Share on other sites
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