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.
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
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
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:
weather on humans
This is from a google search of: 'space
weather' 'humans in space'
NASA Protects its super heroes from space weather
The title seems misleading, because NASA
doesn't seem to be protecting them from space
Click Here to return to the search form.