CompuServe Messages

Rob, Nice entry into your journal. Thanks for sharing it. Found this in my new copy of O. Richard Norton's ROCKS FROM SPACE regarding light phenomena and meteorites. It paraphrases bits I've read elsewhere, so I'll take liberties and further catenate his entry. Meteor light comes from two sources: the burning of the solid body itself (yup, the Ke=1/2 MV**2) and the incandescence of the atmosphere immediately around the burning mass. A meteoroid doesn't become luminous itself until it reaches between 90-60 mi altitude. Below this, the drag of air is adequate to convert some of that kinetic energy into enough heat to melt the outer parts of the meteoroid. This melted material may become incadenscent as it reaches 3000+ degrees F. The surface material liquifies, then further vaporizes. Like you said, the air around the incandescent stone then ionizes, losing electrons. As the atmospheric gases recapture electrons, they release light. A rock a foot or two may generate a glowing air mass hundreds of feet across and miles long via this mechanism. Regarding colors, the composition of the vaporizing material and the composition of the luminous air both contribute. Sodium generates yellow, nickel a green color, and magnesium an intense BLUE-WHITE. These compounds are present in many meteorites. Air molecules may flouresce in excitement with greens and reds generated by nitrogen and oxygen. Additionally, meteorites can change colors in mid-flight, typically going from a brilliant white to a bright red before extinguishing. Well, I thought it was interesting… Catch you later. –Joseph