>From a Space.com article earlier this year: <http://www.space.com/scienceastronomy/top5_myths_020903-4.html>
Top 5 Cosmic Myths (cont.) Myth #4 - Meteors are heated by friction as they pass through the atmosphere . . . This one makes sense, which is why it's so pernicious. But it's STILL WRONG. Meteoroids are tiny bits of dust, rock, ice or metal that have the unfortunate luck of having their orbits intersect the Earth's. When they pass through our atmosphere, they are heated so ferociously that they glow (and at this point are called meteors), and are visible for hundreds of miles. However, it is not friction that heats them. Think of it this way: a space shuttle's tiles are extremely delicate; they crumble easily in your hand. If they were heated by friction as the shuttle de-orbits and enters the atmosphere at Mach 25, the tiles would disintegrate. That's not a very good design characteristic. In reality, it isn't friction, but ram pressure that heats the meteoroid. When a gas is compressed it gets hot, like when a bicycle pump is vigorously used to inflate a tire. A meteoroid, moving at 33,500 mph (15 kilometers a second) or more compresses the air in front of it violently. The air itself gets very hot, which is what heats the meteoroid. That's the fact, not friction. See Next Message for Myth #5: More on this Hot Topic __________________________________________________ Do you Yahoo!? New DSL Internet Access from SBC & Yahoo! http://sbc.yahoo.com ______________________________________________ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
