posted on Feb, 20 2013 @ 10:55 AM
Originally posted by Helious
wouldn't something with that much mass and traveling at such a high velocity create a large crater instead of almost completely evaporating before
hitting the surface?
You (like many people) are not taking into account the density of our atmosphere.
To you and me, since we live in it, air seems like nothing. However, to a big rock, that's traveling along at 18 km/s, hitting the dense air of the
lower atmosphere is like throwing an egg at a brick wall.
These big objects can only fully penetrate the atmosphere if they stay intact. As soon as they start to break up, the surface area to volume ratio
starts to increase, and along with it so does air resistance which has the effect of rapidly slowing down the fragments.
For example - take a handful of dry flour, and try to throw it as far as you can. It won't get very far! Now take the same amount of flour, wrap it
tightly in clingfilm, and try to launch it as far as you can again. It will go a whole lot further thanks to the low surface area to volume ratio.
Our atmosphere is very good as stopping these quite large rocks. The fact that there were only minor injuries due to a 10,000 tonne rock (the largest
since Tunguska) entering the atmosphere is testimony to this.