Heat from the sun?

[orestis]

Hi Everyone,

There a question that has been pestering me for a while and I thought of asking you guys.

What causes the heat that we feel from the sun? Is it the light, nucluer energy going off inside the sun or is it invible elctromagnetic wavelengths such as infra red that heat us?

Thanking you in advance
Cheers Orestis

[CraigS]

Hi Orestis !

Oh boy .. what is the difference between heat and temperature ?

Tricky question to answer .. it all comes back to the more basic principles and Laws of Thermodynamics and ultimately, Entropy (disorder).

In short, all Electromagnetic energy can be turned into either the sensation we relate to as 'heat', or into something we measure and call 'temperature'.

I might let others have a go at trying to explain the connection between heat/temperature and Entropy but the 'heat' we feel, is transmitted away from the fusion process inside the Sun, in the form of the Electromagnetic Spectrum (mainly Infrared).

Cheers

[renormalised (Carl)]

Photons....all of various wavelengths and frequencies, but mainly in the infrared part of the EM spectrum, is what carries the "heat" we feel from the Sun. Your body has millions of specialised nerve receptors in the very outer layer of your skin which detects the incoming IR photons and relays their latent quatity as a nerve impulse to your brain. In essence, they act very much like primitive eyes. They "see" the radiation. The more that strike your skin at whatever wavelength/frequency they radiate at, the hotter/colder you feel. Your conscious mind then puts a subjective, qualitative value to that initial feeling.

Heat is a latent quantity of energy, temperature is the qualitative measurement of the latent quantity of heat. In other words, it's "value added" to that latent quantity.

[mental4astro (Alexander)]

One element from Orestis' question hasn't been answered yet. What Craig and Carl state about what heat is was answered. Its origin though, yes, is from the nuclear fussion that occurs inside the Sun. Heat, light, "raditation" are all components of the electromagnetic (light, microwaves, infrared, UV, xrays, etc) energy given of in the fussion process.

Heat/burning can occur with all types of electromagnetic radiation, it depends on the level of intensity of the particular wavelengths, UV burns (sunburn), raditation burns, etc. The stronger the level, the greater the 'heat' effect. Infrared radiation however, is what we most readily perceive as 'heat'.

I hope this helps.

[orestis]

Thank you very much guys
This has helped me very much in the understanding of heat.

Cheers Orestis