# temperature in space

Discussion in 'General Science' started by aamirali, Jul 3, 2014.

1. ### aamirali Thread Starter Member

Feb 2, 2012
415
1
what is the temperature in space.
Like astronauts in space have how much temperature around them.

Heat travelled from various stars reach earth via radiation

2. ### Brainbox Member

Nov 15, 2010
25
2
At your vague definition of space:
Anywhere between 0 and 200.000 degrees Kelvin.

As there are no molecules around the spaceship, there is also no temperature, as this is defined as movement of molecules.

Last edited: Jul 3, 2014
3. ### BrainFog Member

Jan 24, 2011
122
4
I thought this part of the forum was for electronics chat.

The background temperature of space is about 2.7K (kelvin)

In fact what we see as empty space does contain molecules but I think there are on average only a few molecules per cubic meter.

4. ### wmodavis Well-Known Member

Oct 23, 2010
737
150

panic mode and THE_RB like this.
5. ### alfacliff Well-Known Member

Dec 13, 2013
2,449
428
heat from stars? look up "square law" for the loss of heat with distance.

6. ### Wendy Moderator

Mar 24, 2008
20,764
2,534
Remove the K and you might have it, it is around 3° absolute. This being attributed to the back ground radiation of the Big Bang.

However, in a vacuum in a Faraday cage you can get much colder.

I have worked on sputtering machines where we had high vacuums. Fact is, there are grades of vacuums, near earth and sun not being so good, where deep space is much higher.

7. ### DerStrom8 Well-Known Member

Feb 20, 2011
2,428
1,328
The "K" is for "Kelvin", meaning absolute. He had it right

SO it's not 2.7 thousand, it's 2.7 Kelvin (roughly)

JMW likes this.

Mar 24, 2008
20,764
2,534
Opps......

9. ### studiot AAC Fanatic!

Nov 9, 2007
5,005
513
If you have heard of optical pyrometers you will understand that the 2.7°K is what you would measure using one of these.

An optical pyrometer is a non-contact temperature measuring device that measures the emitted radiation and produces a temperature in acordance Stefan's and Plank's laws (black body radiation).

There is background radiation in deep space that corresponds to this temperature. Some say it is left over from the 'Big Bang', but there are difficulties resolving this interpretation with measurements.

Last edited: Jul 5, 2014
DerStrom8 likes this.
10. ### wayneh Expert

Sep 9, 2010
12,086
3,024
There is a growing discomfort with the Big Bang, expanding space theory as myriad "tweaks" are applied to keep it viable in the face of the data. It might be overturned in our lifetimes.

11. ### studiot AAC Fanatic!

Nov 9, 2007
5,005
513
Yes it might be that is why I phrased my sentence the way I did.

The main point is that the background ratiation is there and measurable, whatever the cause.

12. ### wayneh Expert

Sep 9, 2010
12,086
3,024
Are you aware of Eric Lerner and LPP? He's a notable voice against the Big Bang and you can see his presentation (at Oxford? I think it was) on the topic.

Nov 9, 2007
5,005
513
14. ### alfacliff Well-Known Member

Dec 13, 2013
2,449
428
in response to the origional question, the temprature depends on how much radiation from the sun or other hot bodies you are recieving. in the shade its real low, in the sun, its real hot. actual temprature depends on a lot of variables.

15. ### wayneh Expert

Sep 9, 2010
12,086
3,024
That's him. He's leading a fusion project that may interest some here. It uses a "fancy spark plug" to generate a plasma which then collapses and pinches the fuel enough to trigger fusion. They're "only" 4 orders of magnitude away from break-even and struggling for funding.

Getting back to the topic, Lerner has proposed other interpretations of what the red shift and background radiation is about.

The OP seems to be long gone, but part of the answer to his question is to draw a distinction between energy and temperature. As noted earlier in this thread, temperature is molecular movement. It's what an astronaut might feel as a response of his equipment and skin to the ambient energy balance. Energy is transferred by conduction, convection and radiation. In empty space, radiation is the only method to transfer energy until that radiation strikes an object. An object in space, even our planet, reaches a temperature that balances out incoming and outgoing radiation. There's a lot of conduction and convection within the object, but it's all about radiation once you're in space.

Last edited: Jul 16, 2014
16. ### Metalmann Active Member

Dec 8, 2012
700
223
.."he makes some good points, not just about the Big Bang, but about society and science in general."

Haha, you should ask me sometime about my points on society and science.

I gottts a Million of them...........

17. ### studiot AAC Fanatic!

Nov 9, 2007
5,005
513
I had understood Stephen Hawking has proved that even black holes posses a temperature.

18. ### sirch2 Well-Known Member

Jan 21, 2013
1,008
351
Just thinking about the original question I think it misses the point that we measure the temperature of something so the response is "temperature of what?"

When we measure the temperature on earth for say weather forecasting we measure the temperature of the air, and usually some effort is made to avoid that measurement being affected by radiant heat from the sun. If you threw a thermometer out of a spacecraft you would be measuring the temperature of the thermometer itself. Over time it would radiate away its heat until it reached some kind of equilibrium. If the thermometer was perfectly isolated from any other radiant heat then it would reach 2.7K at which point it would not be able to radiate any more heat.

However if the thermometer was not isolated then it would reach some other temperature and that temperature would be a function of the thermometer itself.

Just as an aside I believe Hawking radiation is different to thermal radiation of black body - http://en.wikipedia.org/wiki/Hawking_radiation

19. ### studiot AAC Fanatic!

Nov 9, 2007
5,005
513
Before astrophysicists invented 'black holes', the best approximation to a black body for the purposes of physical experimentation with Black Body Radiation, Planck's and Stephan's Laws was not a 'something' it was a black hole ie a small opening in a hollow body that was blackened inside. A ping pong ball with a pinhole.
The idea behind this was that once inside any radiation would be trapped and bounce back and fore inside. So pyrometry on the hole would record true black body radiation.