02-16-2013, 07:13 PM
Paul - that's actually correct. Small meteorites are not hot when they land. They are slowed down so much by the atmosphere that a few miles above sea level they almost stop and then fall to the ground under the influence of gravity. Small meteorites hit the ground at their terminal velocity which is typically three or four hundred mph rather than their cosmic velocity of 20-30 miles per second (probably obvious, but cosmic velocity is the speed they had before they entered the atmosphere). They might retain a little heat but certainly aren't glowing hot.
The limit is believed to be around 10 tons. Anything below that will not hurtle into the ground, it'll slow down and burn up or explode. Anything above that will also burn up but will retain some cosmic velocity. Big rocks, we're talking several hundred metres in diameter, will keep their cosmic velocity all the way into the ground. Not that they happen often, but you don't want to be anywhere near one of those. The dinosaurs found that out.
Tom
http://apacificview.blogspot.com/
The limit is believed to be around 10 tons. Anything below that will not hurtle into the ground, it'll slow down and burn up or explode. Anything above that will also burn up but will retain some cosmic velocity. Big rocks, we're talking several hundred metres in diameter, will keep their cosmic velocity all the way into the ground. Not that they happen often, but you don't want to be anywhere near one of those. The dinosaurs found that out.
Tom
http://apacificview.blogspot.com/