asteroid

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bender008

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it seems that were rarely struck by massive asteroids could it be that back than action was very frequent that right now everything is in a very calmer state and more settled because after the Big bang everything was being thrown around in caos and that now that everything is a bit mor e organized?
 
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qso1

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Pretty close but the material from which these meteors originated is believed to be the material that formed the planets in which case its not chaos from the big bang. Just the settling of the primordial material from the formation of the solar system. Of course, it is possible for a big bang interloper just wandering around the Galaxy to encounter Earth but exceedingly rare.<br /><br />The 174 impacts documented seem like a large number until one looks at the times when they are thought to have occured. Mostly millions of years and probably hundreds of thousands to a million years between most major impacts.<br /><br />It should be noted that meteors enter Earths atmosphere on a daily basis but these are too small to impact the surface. These are the most common meteors and range in size from dust spec to perhaps grapfruit. The larger the meteor, the rarer.<br /><br />The last known impact I'm aware of that was of significant size was the one in Tunguska Russia 30 June 1908.<br /><br />Despite all this, all it takes is one good hit but hopefully, a meteor or asteroid of significant size would be detected years before potential impact in which case humanity may be able to respond with a defense of some sort. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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nexium

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It is generally assumed that few massive asteroids were formed the first million years following the big bang, because it is thought that only small amounts of lithium were available to make solid bodies. Asteroids and proto planets however began to form near here about 4.7 billion years ago, which is 9000 million years after the big bang, so likely our galaxy had, and still has trillions of asteroids and comets not orbiting a star, plus millions of asteroids that are in the asteroid belt.<br />About 2000 asteroids have solar orbits that cross the orbit of Earth, so they will likely strike Earth sometime in the next billion years, unless their orbits change. Others that orbit the galaxy have a very low probability of hitting the Earth, but they likely number in the trillions. The probability of a massive hit of Earth has likely decreased at least slightly over the past 3 billion years. Neil
 
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