is the universe warm?

Question

If the sun warms up the Earth and other planets, does that mean the universe is warm and not this cold place we imagine? Also how come we don't see pictures of the sun when people are on the moon and above the Earth? If its so big how come we dont see it in pictures?

Answer 1

The background radiation temperature of the universe is 2.7 degrees Kelvin .. that's above absolute zero. Unless you're close to a star, it's darn cold. As far as photo's on the moon of the sun .. it's too bright. One of the Apollo missions pointed their camera at the sun by accident and it was burned out.

Answer 2

Space technically doesn't have a "temperature" as temperature is a feature of matter, and space is empty (mostly). There is a backround radiation (theorized to be left over energy from the big bang) that is about 2.7 kelvins as mentioned above, but other than that, space is just empty. Since there is no matter to hold heat, it could be said to be cold but if you could "feel" it, it wouldn't be the same sensation as, say, touching a block of ice. Your hand would lose heat through radaition which is pretty slow so it would feel cool, but not really cold. If you were near to a star like the sun, it would actually probably feel warm, as the heat from the star would hit you, in the same way that basking in the sun makes you feel warm.

Answer 3

As you can tell by now your question is more complicated than you thought. First, the people that said space doesn't have a temperature because it is a vacuum are giving the standard answer as taught in most astronomy classes, but there is a problem with that answer because it ignores both the definition of "temperature" and the definition of a "vacuum." I shall deal with each seperately.

SPACE ISN'T A VACUUM; it is NEARLY a vacuum. The density of gas in space varies from place to place, but is generally accepted to be between 0.06 to 1000 atoms per cubic cm (the density of air is about 100,000,000 atoms per cubic cm). The .06 atoms would be in deep space. The 1000 atoms would be in a thick nebula (cloud of gas) like the Orion nebula.

The temperature of a system corresponds to the average energy of the microscopic motions of atoms and molecules in that system. Thermometers are doing nothing more than measuring this average particle motion. So, a thermometer placed in one area of space might read 3 degrees K (-270 C)and the same thermometer placed somewhere else might read say 4 degrees K. An object put at the Earth's distance from the Sun, will reach a max temperature of about 280 K (7 C).

So I have shown that there are particles everywhere in space and that these particles have motion - therefore, by logical progression, we can say that SPACE HAS A TEMPERATURE.

On Earth things heat up and cool down by three different methods: convection, conduction, and thermal radiation. In space, because it is a near vacuum, convection and conduction are for all realistic purposes absent. This leaves only radiation (the transfer of infrared wavelength photons of light) as the way for heat to transfer from a warm body to the surronding enviroment. And guess what; radiation isn't nearly as efficient as
the other two methods. If you microwaved a potato and threw it out of the space shuttle it might take DAYS or WEEKS to achieve thermal equilibrium (to cool down to the temp of the space around it).

But wait; there's more!!! What temperature do you think the air coming out of your hairdryer is? About 120-130 deg F. You could easily blow the hairdryer on your hand for 30 seconds without burning yourself whatsoever. Now try putting your hand in water that is 120-130 deg F for even 30 seconds. You will be on your way to the hospital with burns. What is the difference? The density of air as opposed to water! The denser a substance is the greater the amount of heat capacity it has. We are now ready to go back to space. You could put your bare hand out in space in an area that measures 50,000 deg F (5 times hotter than the surface of the sun) and you would never be burned unless you stayed there for days and days because of the density of the gas around you. You would see the same effect if you put a thermometer in the same 50,000 deg space gas. It would warm up to 50,000 deg EVENTUALLY, but it mile take days or months to get there. What determines how fast the thermometer (or your hand warms up)? Why the density of the gas of course!!! The denser the gas the quicker the warming (or the cooling)..

As you can see sometimes the simplest questions have the hardest answers.

Good Luck
DBM
.

Answer 4

Technically, there's no heat in the vacuum of space. However because of the presence of stars, comets and other celestial bodies, electromagnetic radiation is all around, including gamma radiation, light and infrared radiation. It is probably this that would make the Universe feel hot.

Answer 5

Im not sure why we dont regularly see pictures of the sun, but you can look at the sun through a telescope with a sun filter equipped. And see sun spots and such.

Answer 6

space is definitely colder than Earth. If I'm correct, space doesn't have any medium and it is just empty space. Simply said, in Earth, we have an atmosphere trapping in all the air molecules. When theres molecules, move more, there is more heat.

In space, there isn't any molecules. It is just emptiness. That is why sound doesn't travel in space. Since there is no molecules, it is hard for it to generate heat energy.


If i'm wrong, somebody please correct me.

Answer 7

the vast distances of space in between makes it cold