space temperatre?

Question

how cold is space?

Answer 1

Temperature is the measure of the average kinetic energy of the particles of a substance. The higher the temperature, the higher the average KE of the substance's particles, the lower the temperature, the lower the KE.

Space is a vacuum (or near enough). It does not make any sense to speak of the temperature of a vacuum since a vacuum has no particles which to measure their average kinetic energy.

In order the measure the "temperature" of space, one must instead measure the temperature of something placed out in space...like a thermometer. If a thermometer is placed out in space, it will begin to absorb energy from the sun or other stars in the form of electromagnetic radiation (light). In addition, the thermometer will emit electromagnetic radiation (mostly in the IR end of the spectrum). If the rate at which the thermometer emits energy exceeds the rate at which it absorbs it, the temperature will fall. As the temperature falls, the rate at which energy is emitted slows, eventually reaching an equilibrium temperature (rate emitted = rate absorbed).
This equilibrium temperature depends greatly on the location of the thermometer relative to near by heat sources (like the sun). The equilibrium temperature on the dark side of the moon will be well below the temperature measured on the sunny side of Mercury.

At the Earth's orbital distance from the sun, a sun-shielded thermometer will reach an equilibrium temperature of about 5 K (-268.15 degrees C).
Interplanetary space is said to have an equilibrium temperature of about 3 K (2.725 K).

Answer 2

Tough question. It depends how you are defining temperature. If you define temperature as the friction created in proportion to the speed of the molecules in a substance (this is how we measure all temperatures in normal day to day life: air temp, water temp, etc) then the temperature of space is essentially absolute zero (or more correctly an undefined value) since there is a near perfect vacuum in space and thus no molecules to bounce around.

Temperature in space is most often described in terms of radiation. Radiation from the sun will heat up one side of a spacecraft to very high temperatures. While the other side of the spacecraft is radiating heat into the vacuum and becomes very cold. This is the effect of the space radiation and vacuum environment and not neccesarily the "temperature of space" though.

Astronomers refer to the "temperature" of space or of the universe in terms of the energy level of the background cosmic radiation left over from the Big Bang.

So long story short: there really isn't a temperature in space in the terms we think of in our everyday experiences.

Answer 3

...and just to be complete pedantic about the situation. The universe has an average temperature of 2.73 K.

This calculation comes from something called Wein's Law which says:

(temperature)(wavelength) = constant

From measurements of the cosmic microwave background (as mentioned before) we get an average wavelength of about 1.9 mm which is the peak of the blackbody spectrum of the universe.

Putting this into the formula, we find that this wavelength corresponds to a temperature of about 2.275 K.

Answer 4

space is very cold.the atmosphere above us is hot because of the sun's heat reflected by the earth and also because of the heat being trapped by the greenfield gases.

Answer 5

I believe -431 below zero or what they call absoulate zero