hobbes4star 0 #26 October 7, 2002 talk about winning the lottery. damn how unlucky can you get??if fun were easy it wouldn't be worth having, right? Quote Share this post Link to post Share on other sites
billvon 2,435 #27 October 7, 2002 OK, first off, why does everyone assume space is cold? It has no temperature; there's no air there. If you're in the sun, you warm up until you radiate away as much heat as you absorb. If you're in the shadow of a planet, or far from the sun, you cool down until you absorb as much heat (from IR radiation from the planet etc) as you emit. Most meteorites do not hide behind planets, and so are fairly warm from being in the sun. Second, even if they started out cold, why would one assume they stay that way? Remember E=.5MV^2. Meteors have a lot of V^2, so they have to dissipate it as heat. Some of that goes into the atmosphere and makes that pretty display, but some of it ends up in the rock itself. An exception is a tiny meteor that slows very high in the stratosphere and takes 4-5 minutes to fall to earth; since the stratosphere is cold (and there _is_ air there) then it can cool off. Meteors that make it to the ground intact are pretty rare. They have to be big enough to not disintegrate up high, but small enough so that atmospheric drag can decelerate them to a survivable impact speed (<200mph or so.) Big ones that do not slow before impact, of course, make big holes. That same E=.5mV^2 can give them the explosive force of a nuclear weapon. Quote Share this post Link to post Share on other sites
AggieDave 6 #28 October 7, 2002 Dude, you're killing the thread...hehe --"When I die, may I be surrounded by scattered chrome and burning gasoline." Quote Share this post Link to post Share on other sites
nws01 0 #29 October 7, 2002 ChromeBoy came and picked up Bill Von and I while we were at Perris and he told Bill all that stuff. Quote Share this post Link to post Share on other sites
seedy 0 #30 October 7, 2002 Quote Apparently, railroads routinely dump raw sewage onto the railbed. Unfortunately, they were over a bridge this time. Not anymore. This incident helped put rules in place that railroads have to follow. Now they have to have chemical toilets and/or holding tanks. I intend to live forever -- so far, so good. Quote Share this post Link to post Share on other sites
mre 0 #31 October 8, 2002 When billvon replies to my post, I feel I must take up the challenge! Quote OK, first off, why does everyone assume space is cold? It has no temperature; there's no air there. This is true; space is not at thermal equilibrium, hence it does not have a temperature. You could also say that it has several temperatures. In other words, depending on with which heat source you exchange energy, you will assume different temperatures. If for instance you were to exchange energy only with the sun, as is approximately the case for the focal point of a solar oven, you would reach the same temperature as the surface of the sun. If you were to interact only with "empty" space, you would reach 3 kelvin. An asteroid will reach much the same equilibrium as does a planet. This does not mean that being in the sun will make it hot, though. The earth is warm mostly because of the greenhouse effect (which in effect makes the surface interact more with the sun, less with empty space in the above picture). The moon is much colder: http://www.monstein.de/astronomypublications/MoonEnglishHtml/Moon2001V2.htm Exactly as Bill writes, temperature varies greatly between day an night. The average, which should be similar to the approximately constant temperature of a small body close by, is quite low however: -56 C (according to the above article). In conclusion, meteorids (= a meteorite still in space) are quite cold when close to earth. I'll stop here. To be continued only in the unlikely event of public demand. Quote Share this post Link to post Share on other sites
nacmacfeegle 0 #32 October 8, 2002 "In conclusion, meteorids (= a meteorite still in space) are quite cold when close to earth." I'd go with that, I seem to recall that a lot of meteoroids actually consist of an agglommeration of ice and various minerals...... "I'll stop here. To be continued only in the unlikely event of public demand." No no, tell us more, I'm bored at work.....-------------------- He who receives an idea from me, receives instruction himself without lessening mine; as he who lights his taper at mine, receives light without darkening me. Thomas Jefferson Quote Share this post Link to post Share on other sites
quatorze 1 #33 October 8, 2002 Quote Remember E=.5MV^2. Who the F#$% remembers this? Tell me I am not the only one that Billvon makes feel just the least bit inept? I'm not afriad of dying, I'm afraid of never really living- Erin Engle Quote Share this post Link to post Share on other sites
nacmacfeegle 0 #34 October 8, 2002 "Who the F#$% remembers this?" Skulks in the corner, raising hand...... half emmm vee squared is what gives us ....Kinetic energy........-------------------- He who receives an idea from me, receives instruction himself without lessening mine; as he who lights his taper at mine, receives light without darkening me. Thomas Jefferson Quote Share this post Link to post Share on other sites
Cajones 0 #35 October 8, 2002 I remember that, too. But, I didn't go to school in South Carolina... The laws of physics are strictly enforced. Quote Share this post Link to post Share on other sites
quatorze 1 #36 October 8, 2002 Cajones, I said I went to school, never said that I lurnt nuthin" I'm not afriad of dying, I'm afraid of never really living- Erin Engle Quote Share this post Link to post Share on other sites
happythoughts 0 #37 October 8, 2002 Quote talk about winning the lottery. damn how unlucky can you get?? Odds of winning the lottery in Florida, 1 in 14 million. Odds of lightning strike, 1 in 3 million. Oh well, only 4 more lightning strikes to go. Quote Share this post Link to post Share on other sites
billvon 2,435 #38 October 8, 2002 >An asteroid will reach much the same equilibrium as does a planet. > This does not mean that being in the sun will make it hot, though. Right; that has a lot to do with surface albedo and emissivity. Dark objects tend to have a higher surface temp since they absorb more heat. >The moon is much colder: Well, it's warmer and colder. Daytime temps are around 100C; nighttime temps are around -150C, due both to lack of atmosphere and those very long days. Not sure what the core temp is, but that's heated a bit by tidal effects anyway. >I'd go with that, I seem to recall that a lot of meteoroids actually > consist of an agglommeration of ice and various minerals...... Well, comets certainly consist of ice and other volatiles, but remember that they start boiling off long before they pass the earth's orbit (those volatiles are part of what make up a comet's tail.) Quote Share this post Link to post Share on other sites
ChileRelleno 0 #39 October 9, 2002 Gyn & tonics anyone? ChileRelleno-Rodriguez Bro#414 Hellfish#511,MuffBro#3532,AnvilBro#9, D24868 Quote Share this post Link to post Share on other sites
