17.2
The Earth's atmosphere, asteroid paths and multi-hits
 
  Before we look at the history of general conditions for life and the age of the planet, it is important to spend a short moment on the effect of the Earth's atmosphere on any large inbound object such as an asteroid.  
17.2.1 The constant denial of large asteroids impact on life on Earth  
  On any clear night, you can look at a full moon and see with your own eyes various shapes of colour on the surface of the Moon. If you were to look through a pair of binoculars, you could clearly see these shapes are created by massive asteroid hits onto the surface of the Moon.  
  That the moon is cratered by literally thousands of impacts from asteroids has been known for hundreds of years. But what remains a contentious issue for contemporary science is just how many, how large and what impact asteroids have had on the planet Earth. South Pole.  
  Remarkably, there has never been an open general acceptance in the science community that the Earth has suffered at least a similar number of asteroid impacts as the Moon. It may also surprise you a majority of scientists remain unconvinced that there is sufficient evidence as to massive asteroid impacts at least as large as those on the surface of the Moon. Hot debate still reigns as to whether the gulf of Mexico was actually created by a giant meteor 65 million years ago for example.  
  One contemporary and generally supported model is that the Moon acts as a kind of asteroid magnet, "warding off" killer objects. While this sounds reasonable for a proportion of incoming objects, the fact remains that the Moon does not shield all the Earth all the time. There are periods ever day where parts of the Earth are directly exposed. This theory also discounts the ability of large objects squeezing"underneath" the Moon's orbit and into the Earth's atmosphere  
17.2.2 The effect of the Earth's atmosphere on an incoming asteroid, comet or meteor  
  The Earth's atmosphere is not as "weak" a defence system as you might think. Apart from generally keeping most harmful gamma rays and x-rays away, the 120km of air and other particles has the capacity to substantially slow objects down entering the atmosphere.  
  The effect of gravity and attraction tends to warp the effect, however, we know from manned space flight that re-entering the Earth's atmosphere at any speed causes huge flames as the hydrogen and oxygen in the air burns from the friction on the outside of the craft. We also know the spacecraft's outer skin gets extremely het as well as the object buffeted (push and pull) as its hits varying densities in the atmosphere, causing it to shake.  
  NASA understands that if the Space Shuttle tilts too hard into the Earth's atmosphere and comes down at any speed beyond 27,000 km ph, the spacecraft will burn up. The effect of the Atmosphere on smaller meteorites is already well understood- "shooting stars" in the night sky are meteorites burning up in our atmosphere  
  Therefore we know that if an object comes in at 90 degrees, it will encounter greater resistance than if it comes in side on. We also know that any object traveling at speed must withstand tremendous friction to hold together.  
17.2.3 Do asteroids, meteorites hit in one place or in a series of hits?  
  Given the general unacceptable by science as to the seriousness of studying asteroid and meteor hits on the Earth's surface, it is not surprising to find that the common held view is that one meteor = one crater.  
  This is in spite of the strong understanding that comets, meteorites and asteroids are not manufactured by the conditions of space as perfect spherical shapes. Instead, these pieces of rock, metal or ice and dust are infinitely varied in shape, mostly irregular rather than spherical.  
  Without even looking heavily into the mathematics of speed of asteroid, resistance of atmosphere and effect on the asteroid, common sense tells us that an irregular object traveling at speed into our atmosphere would most likely break up into pieces before the pieces hit the surface.  
  We also know that an object will face less resistance if it travels into our atmosphere sideways, rather than 90 degrees. Presumably this must also have some impact on the path of any meteor, encouraging the object to finish its final approach into our lower atmosphere (if it is big enough) on an angle.  
  It would also hold true that if a big enough object came toward the Earth at a too shallow angle, the object would simply "bounce off" the atmosphere.  
  This combination of intense het, the object splitting up, means that by rights, when we find one crater, there should be more. Contrary to the current view, one comet/meteor/asteroid = multi craters.  
17.2.4 The thinner outer atmosphere of the equator vs the thinner inner atmosphere towards the poles  
  Another area we need to consider regarding the inbound path of large objects onto the surface of the Earth is the relative difference in densities of the outer atmosphere and inner atmosphere of the Earth. Around the equator, the atmosphere is thinner in the upper atmosphere, compared to the poles. The reverse is true when you get further into the atmosphere.  
  This difference is strong enough that an object would find it "easier" to enter around the equator and skew further towards the North Pole or the South Pole. We should therefore find more meteorite impacts initially occurring closer to the equator than closer to the North or South pole.  
17.2.5 Do fragments of asteroids, meteors hit in clusters or lines?  
  The next question is whether the fragments of asteroids broken up in the atmosphere hit in a cluster or in a line?  
  To answer this, we need to consider the combined effect of the atmosphere's friction, skewing of objects to enter sideways to come in around the equator, but away closer into the atmosphere  
  Under such pressures, we must assume that the largest objects will have the greatest power to continue towards the surface while the smaller fragments torn off in the atmosphere will travel at slower speeds and be more influenced by the atmosphere Given these relative pressures on the object, there is no other likely conclusion except for patterns of asteroid, meteor/comet hits in curved or slightly curved lines. We also expect to see a large crater, surrounded by smaller impacts as well as a line of successively smaller craters as the parts of the object that broke off in the atmosphere come down.  
17.2.6 What does all this mean r/e deadly asteroids, meteors and comets?  
  We now know that the Earth's atmosphere is capable of breaking up large objects into smaller objects spreading out the fragments in a line of impact zones burning up a sizable amount of the object in the process.  
  All these factors are good when you consider the strength of a 4km wide meteor traveling at 100,000km per second towards the Earth.  
  In recent years, science has provided a number of comparisons regarding the size of meteors and their potential impact on life on Earth if they hit. For instance, a recent US defence dept. analysis stated that a meteor 1/10th the size of Hale-Bopp would be large enough to destroy up to 1 billion people and devastate the Earth.  
  It is unlikely however, that this analysis took into account the process of the meteor through the atmosphere, breaking up, and various impact zones. All these factors lessen the killing potential of the meteor. Once we take these factors into account, a 4km object would more than likely break up into at least 1 to 2 main components with anything up to half a dozen smaller fragments. Secondly, the smaller objects would move slower in the atmosphere, again lessening their damage. Thirdly, the friction within the atmosphere would help burn up to 30% of the main body of the largest parts and anything up to 80% of the medium sized pieces. Finally, the impacts would be spread out, possibly over a 200km to 600km curved line.  
  The worst impact from a 4km asteroid would end up being one to two impacts of around 200m to 400m across. Certainly large enough to destroy a major city, or close cluster of cities, but not enough to wipe out the whole of North America or Europe. Given these considerations, the most people a 4km wide asteroid could directly kill would be no more than 50million to 100million plus. The environmental impact in terms of global cooling might contribute an additional 50million to the death toll, but certainly not a mass extermination of the planet.  
17.2.7 What damage does a large asteroid/meteor cause?  
  There is a sequence to the damage that any large object causes to the Earth and the life ecosystem, the first beginning with localized Earthquakes and Firestorm.  
  (1) The nuclear fireball and Earthquakes  
  At the point of impact of a large fragment of meteor, the impact would likely create a huge crater. For a 50metre wide fragment, the crater could be as wide as 6km across and up to 1km to 2 km deep. The impact would pulverize the displaced rock and soil into fine particles, pushing them high up into the atmosphere, to settle back down over years, sometimes even hundreds of years.  
  Immediately upon impact, the meteor would also cause a sudden increase in kinesis shockwaves near ground level atmosphere, causing a huge fireball of burning hydrogen and oxygen to erupt from the impact zone for possibly 80km around the impact zone (if it was a 50m wide meteor). This would burn all the trees and plants up like a giant forest fire, with the wind, blowing every man made structure flat for around a 30 to 40km radius.  
  At the same time, the shockwaves from the impact would cause major Earth quakes at 7 or above for possibly a 100km radius, extending beyond this point if the impact was nearby to a major fault line. This all happens within the 1st ten minutes of the meteor hitting.  
  (2) Tidal waves across the oceans  
  Within 7 hours of the hit, you would expect major tidal surges hitting other continents nearby as the impact reverberates through the Earth's surface and mantle.  
  (3) Volcanoes  
  Within 24 hours of the hit, you would expect volcanoes in the region to be active, releasing the stress within the Earth's surface from the impact.  
  (4) Severe cooling of the region  
  Finally, apart from the after shocks, you would expect a major warming and then cooling of the region because of the tons of fine dust in the air reducing the arrival of sunlight, not interacting higher in the atmosphere. The temperature around the impact zone may even drop by more than 15 C. This may bring on the onset of severe winter conditions, causing local bodies of water to freeze and the creation of glamorization.  
  Eventually the dust will settle, carried by the winds over an area from the impact site for potentially thousands of kilometres, burying some or all of the burnt forests in thick layers of fine dust. In maybe 40 million years, we may rediscover this region and tap into the burn forests for coal or even oil, if the impacts are more recent.  
  This pattern of severe climactic change (in order) is the same for every major meteor/asteroid hit that has happened and will happen on Earth.  
17.2.8 What does this mean for future asteroid hits?  
  While the good news might be academic to someone living on the future impact zone for a large meteor or asteroid, the conclusion from this section is that asteroids need to be of a substantial size in order to cause mass extinctions of the planet. Much larger than we have previously thought.  
  Humanity will simply not be exterminated from the arrival of a 10km to even 20km across asteroid/meteor into our outer atmosphere. Such a large object would cause a significant change in atmosphere however. Mass extinctions of the sort that have happened for hundreds of millions of years (mass extinction = where more than 90% of life was killed), would take an object of immense relative size (50km across or more).  
  Again the good news is that these objects are much rarer than the hundreds of smaller objects (2km or less) that cross our Orbit ever year.  
17.2.9 Further proof of large asteroid hits  
  The most stunning proof of asteroid hits on Earth remain the heavy core elements above Iron (26). That Gold exists, that Uranium exists is living proof of previous asteroid hits on Earth.  
  For example, using our knowledge of the elements from chapter 7, we can see a natural relationship between the three major classes of asteroids and meteorites and the constituent elements their impacts would cause.  
  Carbon based asteroids (most common in the Universe) On impact, would create sufficient kinesis to form heavier elements such as o Potassium (19) o Calcium (20) o Manganese (26) o Surface Iron (26) o Nickel (28).  
  The second most common asteroids, comets and meteorites are the oxygen/silicates. On impact, the oxygen/silicates would create sufficient kinesis to form heavier core elements such as: o Strontium (38) o Silver (47) o Tin (50) o Cadmium (48).  
  The third, and least common asteroids and meteorites being the iron structures on impact would create sufficient kinesis to create the heaviest elements, including: o Gold (79) o Mercury (80) o Lead (82) o Uranium (92).  
  If you are still not convinced that asteroids and meteorites are the catalysts that create these heavier elements, simply have a look at any atlas that shows the various locations of "heavier" elements and their approximate position relative to structures such as: deserts, deformed coastlines and o mountain ranges. While significant pressures over millions of years can assist in forming "reefs" of heavier elements, surface minerals correspond strongly to geological environments consistent with what you would expect from the result of large impacts. ( We will discuss this in greater detail further into this chapter).  
     
 
<<Back       Continue>>
 

Copyright © 2009 UCADIA. All rights reserved.