If space is cold?

Question

Space is freezing right? How come the sun is the hottest thing and stays that way. Sun is like the size of a grian of sand compared to how big and cold the universe is. So in essence space is cold how does the sun stay warm?

Answer 1

Wow, lots of answers blackcatheaven. I am clearly not as erudite as others, but I think I see what they are getting at. Take "cold" for example. Why do I think an ice cube is cold? Because when I touch it, my body responds to the movement of heat *from* my body *to* the ice cube. The same is true for a warm fire except my body reacts to the movement of heat in the other direction: from fire to me.

If you think of *empty* space in the same way it is the ultimate in cold. If you stuck your bare finger into empty space (don't try this at home!) your body would feel the heat leaving your finger into, well, nothingness; but that heat transfer from your body to empty space would register to you as "cold"; very cold. Since empty space doesn't "warm up" it would feel as cold as cold can get.

Other answers remark that space isn't really completely empty. There is some heat energy, enough that people often talk about space being 3 degrees above absolute zero. So, you wouldn't really be leaking heat into absolute zero (as cold as anything can get) but still it would feel as though it were. It is also true that there are particles or atoms around though not many. You might heat up a hydrogen atom or two if you were in deep space, but still your body would say "Space is cold."

That means, of course, that the sun in order to keep from being cold must be making energy: light and heat. It soes both and as other answerers have so kindly pointed out the sun uses nuclear fusion to convert hydrogen into helium in a way that produces --because there is so much hydrogen to convert-- lots of both light and heat.

Anyway, you have had a number of good answers.

HTH

Charles

Answer 2

The earth's atmosphere which is made of gases acts like a piece of glass and keeps heat from easily escaping into outer space. It also stays in place because of forces like gravity and the magnetosphere which deflects the solar winds that would strip off the atmosphere in a heartbeat. Its the same for the sun even though the sun has a different ratio of chemical elements and releases its energy. It also has gravity, an atmosphere (the corona) and the Parker spiral a magnetic field to protect itself.

Then there is the interplanetary medium or plasma which extends throughout the solar system and is generated by the sun. It effects everything. The notion that space is considered to be a vacuum or filled with an "aether", or just a cold, dark vacuum continued up until the 1950s. Tufts University Professor of astronomy, Kenneth R. Lang, writing in 2000 noted, "Half a century ago, most people visualized our planet as a solitary sphere traveling in a cold, dark vacuum of space around the Sun."

Answer 3

Temperature, or heat energy, is a measure of the motion of an objects' particles. An object that has had heat energy removed--i.e. been "cooled down"-- to Absolute Zero means that it particle motion has completely stopped.
Space is so relatively empty of particles to be moving that is has an overall temperature of approximately 3 degrees Kelvin--or 3 degrees above Absolute Zero.
The sun converts approximately 400 million tons [that is 800,000,000,000 pounds] of hydrogen into helium every second through the process of nuclear fusion. The total mass of the four hydrogen atoms fused together is more than the resulting mass of the helium atom that is formed. Some of the mass was converted into energy in the form of quanta of electromagnetic radiation or photons of light. The rate of conversion of matter into energy is given in the equation E=mc^2.
So, through fusion, the sun creates its own heat energy or particle motion. That energy is radiated out and the photons then can possibly give some of their kinetic energy [i.e. their energy of motion] to things they hit. Since there is not much in space for the photons to hit, they don't give there kinetic energy up until they hits things like the particles in you sitting out in the sun. When they strike you, that kinetic energy is converted into moving around the particles in your body a little more energetically making you feel heat or warmth. So, just go get a chair, get some sunscreen and get a tan while thinking about all this.

And for a previous answerer, space is not empty. The density or particles is so infinitesimal, that for certain calcuations it is considered a vacuum. But, since matter and energy are interconvertable, there is always something in a given region of space, whether it be particles or electromagnetic radiation.

Answer 4

The intense gravity of the sun keeps nuclear fusion happening in the sun. Space may be cold but that's because there is nothing there to be heated by the sun. If you were in space and could see the sun, your blood would boil from the heat without thermal protection. Without a space suit to keep you pressurized, your blood would boil at room temperature anyway.

Answer 5

The warmth of the sun has nothing to do with the 'coldness' of space. It's using hydrogen fusion as an energy source, and will continue to do so until it runs out.

In it's death, the sun will be as cold as the space around it, but that won't be (hopefully) for billions of years.

Answer 6

Cold is a mute term. Really it just means the absence of heat. Since there is very little matter in space, there is very little heat. The sun, and other stars, have huge amounts of matter in a constant state of thermonuclear fusion... releasing energy in the form of heat.

Answer 7

Space isn't cold. Temperature is a measure of how excited the atoms of a thing are - how fast they are vibrating. There are no atoms in space.

Answer 8

Fusion - the sun has it's own supply of fuel, hydrogen, which it uses to generate energy.

Answer 9

QuatumP - great answer, if you were talking to an undergraduate. However, I suspect this person wanted a basic answer. I'd bet she will not take the time to read your missive.

If you want to be a writer, and your knowledge obviously is quite extensive, learn to write for the audience.

Answer 10

Space has no atmosphere so therefore it can't be cold.