Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: cuso4 on 18/05/2004 08:16:45
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Does temperature decrease or increase as you going away from the Earth's atmosphere?
Angel
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It varies. On the small scale it decreases, on large scales it increases. On medium scales it wobbles [:D] http://liftoff.msfc.nasa.gov/academy/space/atmosphere.html
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That's a good link Dan - Thanks!
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John - The Eternal Pessimist.
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Surely (unless you're eventually heading straight for the Sun)...one would expect the temperature to drop as you leave the atmosphere.....forgive me if I've misinterpreted the question but as I understand it...space is well cold !!
'Men are the same as women...just inside out !' (https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Finstagiber.net%2Fsmiliesdotcom%2Fcwm%2Fcwm%2Frcain.gif&hash=32ae7f4f03d740b017b01cda28addd79)
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Actually, it is both cold and hot at the same time. Temperature is a measure of the average velocity of the particles making up the material you are concerned with. In space, there is a very low particle density, relative to what we are used to on earth anyway, and the temperature is very high. But, because there are very few particles, the major heat transfer mechanism is radiation, not convection. You are right that as you move away from the sun the temperature gets colder, primarily because the sun (and the earth's magnetic field) is what is exciting the particles around the earth.
For a spacecraft, the temperature on the side facing the sun can be extremely hot and the side away from the sun gets very cold because all the heat radiates away and is not replaced or held by air. That's why the apollo spacecraft were made to spin - to keep the temperature even on all sides. More modern craft like the shuttle have better heat control (radiating panels in the doors to the cargo bay) and don't have to spin constantly.
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John - The Eternal Pessimist.
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I stand corrected and educated and your info is appreciated....which is what this site is all about....thanks John.
'Men are the same as women...just inside out !' (https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Finstagiber.net%2Fsmiliesdotcom%2Fcwm%2Fcwm%2Frcain.gif&hash=32ae7f4f03d740b017b01cda28addd79)
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quote:
Originally posted by tweener
Actually, it is both cold and hot at the same time. Temperature is a measure of the average velocity of the particles making up the material you are concerned with. In space, there is a very low particle density, relative to what we are used to on earth anyway, and the temperature is very high. But, because there are very few particles, the major heat transfer mechanism is radiation, not convection. You are right that as you move away from the sun the temperature gets colder, primarily because the sun (and the earth's magnetic field) is what is exciting the particles around the earth.
For a spacecraft, the temperature on the side facing the sun can be extremely hot and the side away from the sun gets very cold because all the heat radiates away and is not replaced or held by air. That's why the apollo spacecraft were made to spin - to keep the temperature even on all sides. More modern craft like the shuttle have better heat control (radiating panels in the doors to the cargo bay) and don't have to spin constantly.
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John - The Eternal Pessimist.
John, brilliant explanation. That's exactly what I was looking for.
Angel
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Yes, your responses are very good. It's a complicated question, and can only be answered by being very careful about WHAT temperature you are measuring. The atmosphere has a very complicated temperature fluctuation, and once we are exo-atmospheric, we must be very careful about WHAT we are actually measuring the temperature of. An apollo command module, or the surface of the moon have their own temperature profiles, but I think your question is asking about the temperature of space itself. Of course that would be "empty", so we can't talk sense about its temperature, unless perhaps the microwave background radiation at 2.7 K. Otherwise, space isn't empty, of course, and depending upon where you go, you will find charged particles, molecular hydrogen, gaseous molecules, dust, nebula, stars, galaxies, the whole shebang. The temperatures of all this are one of the key parameters astronomers like to measure using the radiation we can see from earth or near space.
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quote:
Originally posted by tweener
That's why the apollo spacecraft were made to spin - to keep the temperature even on all sides. More modern craft like the shuttle have better heat control (radiating panels in the doors to the cargo bay) and don't have to spin constantly.
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John - The Eternal Pessimist.
Getting back to food...that bit made me think of a chicken on a turning spit roast or rotisserie!!...sorry people...........please continue with your science shpeel and I'll just shut up and get an education.
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Actually, Neil, the Apollo astronauts called it the "barbeque roll", so you're right on the mark.
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John - The Eternal Pessimist.