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We understand that the temperature of the thermoshere gets as high as 1700 degrees celsius, but if you were outside in the thermosphere it would feel cold... or you would freeze. Is this true? Why is this?
Question Date: 2008-02-09
Answer 1:

While particles (molecules) in the thermosphere can get at hot as 1700 degrees Celsius, they are few and far between. Additionally air temperature is a measure of kinetic energy of air particles (molecules) not the total energy stored within the air space. The air in the thermosphere is very thin (the few particles) there is little kinetic energy and can not be compared to air closer to the earth.

Although the measured temperature is very hot, the thermosphere would actually feel very "cold" to us because the total energy of only a few air molecules residing there would not be enough to transfer any appreciable heat to our skin. Therefore the overall temperature feels cold (not that you would have exposed skin) if you got hit by one of the particles it would burn right through you.

Hope this answers your question.

Answer 2:

Space is not cold.

What is correct about the above answer is that the air in the upper atmosphere is very thin. This has the consequence that energy transfer due to radiation is more important up there than is energy transfer due to conduction or convection. Being in the Earth's extreme upper atmosphere is like being in space for this reason: the energy you pick up due to conduction or convection is minimal.

Any object in space is going to have an equilibrium temperature - this is the energy that it absorbs from light minus the energy that it radiates back into space. The darker the object (i.e. lower albedo), the more energy it will absorb, and so the warmer this equilibrium will be. The more light that it receives, the warmer it will also be. Earth is at such a distance from the sun and has such an albedo that its equilibrium temperature is about 0 degrees C (although it differs with latitude as you might expect). It is warmer on the surface of the Earth due to the greenhouse effect: infrared light emitted from the Earth's surface will be reabsorbed by greenhouse gasses such as water vapor or carbon dioxide, so in order for light to escape, it has to be emitted from high enough in the atmosphere that it will not run into gasses that can absorb it, where it is colder due to the temperature curve of the lower atmosphere (this altitude is about 5000 m and varies from place to place due to the presence or absence of water vapor, but is getting higher as more greenhouse gasses are emitted, which is also why the surface gets warmer as a consequence).

Your spacecraft is going to emit light the same way, and so have an equilibrium temperature - unless, of course, your spacecraft also has an internal heat source, which any spacecraft that is not entirely solar-powered will have. This heat source will add additional heat that the craft will have to radiate, so its temperature will be warmer than the equilibrium created by the craft's albedo and its distance from the sun. In general, a spacecraft with human beings on board will generate so much heat that it will have more trouble getting rid of excess heat than keeping it in. This is where the answer above is wrong: space is insulating, like wearing a warm blanket, because you can't lose heat to convection while in space. A ship in space is like a warm drink sitting in a thermos.

The reason why the uppermost part of the earth's atmosphere is so hot is because it is bombarded by high energy particles from space, which allows it to reach a higher temperature than it could were it to remain molecular. Your spacecraft, which is made of molecular matter, won't be ionized, so will not be affected by the processes that make the ionospheric temperature so high.


Answer 3:

At the boundary between Earth and space, charged particles and fields co-exist with Earth's neutral atmosphere and cause a continual tug of war between the neutral and ionized gases. This region is buffeted by Earth weather from below and the Sun’s radiation from above, making it a complicated place. Events like hurricanes can create waves that travel all the way up to this region, while the Sun frequently releases blasts of solar material that can impact at the same time. This changes the shape of the very boundary between Earth and space and can garble some of the signals being transmitted from our satellites.
read here It's an announcement for a talk by a woman at Goddard.

This wikipedia article on space weather has a description of its effect on humans in space:
space weather on humans

This is from a google search of: 'space weather' 'humans in space' NASA Protects its super heroes from space weather read here

The title seems misleading, because NASA doesn't seem to be protecting them from space weather.



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