# How is sunlight radiation produced?

1. Sep 20, 2004

### avinsinanan

I am confused as how sunlight and radiowaves are produced in terms of radiation.

I am familiar with how Aplha, Beta, Gamma and Xrays are produced. I am to understand that Radio, Gamma, ultraviolet rays and microwaves are all types of radiation.

I was wondering the following -

1. Sunlight (The visible spectrum), how is it produced? Do eletrons move from a higher orbit to a lower orbit? Or do the Neutrons split up into an electron and a proton and the excess energy is given off a radiation - or is that for gamma only?

2. What determines weather it's Ultraviolet, Radio , Microwave or even visble light, is it the the electron orbit jump that determines its type. For example if it jumped from orbit 4 to orbit 1 it may be unltraviolet.

I tried reading up many sites on the net and i have not been able to get the answers.

Yours Respectfully
Avin Sinanan

2. Sep 20, 2004

### humanino

Welcome to PF Avin !

Your question is a very difficult one.

The photons are essentially produced in the innermost layer called the core, where the temperature reaches 15,000,000 K ! (27 million degrees Fahrenheit) Different calculations give results from 13,000,000 K to 25,000,000 K. The density in the core is ten times that of lead, yet it keeps in a gaseous state at such high temperature. Thermo-nuclear reactions occurs here : atom's nuclei fusion together to form heavier nuclei. In the process, some mass is "lost", and according to Einstein's $$E=m c^2$$ energy is created, some of which in the form of electromagnetic waves in a continuous spectrum. We know that hot bodies emit radiation with a spectral distribution given by the Planck formula -- so called black body radiation that is continuous for all practical purposes. The radiation, in principle, is discrete, however the emissions are broadened by the pressure of the gases comprising the Sun. The specific emissions are so close together and so numerous that they could not be resolved experimentally. Anyway, the light still has to reach the surface.

There are three ways of conducting energy towards the surface : conduction (collisional transfer of energy between atoms), convection (motion of heated material, such as bubbles) and radiation. Only convection and radiation transfers are important in the Sun. The opacity of the layer determines which method is dominant. When the temperature drops in the outer layers of the solar interior, the protons and electrons recombine to form atoms and the opacity goes up. High opacity slows the transfer of energy by radiation, so bubbles form. These bubbles are hot and low in density, thus starting a convective flow. The absorption occurring with atomic electrons produces dark strips over the continuous sun spectrum, called "Fraunhoffer Dark Lines". The element helium was first discovered from its absorptions in the solar spectra. The Sun is, at present, about 70% hydrogen and 28% helium by mass everything else ("metals") amounts to less than 2%. Only the upper atmosphere can be analyzed in details, and is enriched in hydrogen (which "burns" in the core) : in details, the atmosphere composition is 92.51% hydrogen, 7.36% helium, and 0.13% is seventy-two other elements. Oxygen and carbon are the most abundant of the trace solar elements. Closely following these elements are nitrogen, neon, silicon, magnesium, iron, and sulfur.

We do not fully understand the complicated mechanisms that take place on the surface of the Sun. Approximately 40% of the emitted energy is in the visible portion of the spectrum, 50% is in the infrared, and the remainder is in the ultraviolet.

Plenty of infos
NASA 2000 August 15
Solar spectrum

3. Sep 22, 2004

### avinsinanan

Thanks

Hi thanks for the response.

I was also hoping how would one go about producing a local X ray or gamma maicrowave source and the would like to know the atomic particles belhave.

Let me explain -

Your miccrwave oevn produces microwaves but how it it produced - Does to micowave have some atomic componeent that lets electons jump from a higher orbit to a lower orbit and realease the extra energy? or does it slip neutrons up to an electron and a pronton?

You see am trying to figure out what makes a mircowave a microwave and what makes an unltra viloet wave an unltraviolet wave... what must happen to an atom for it to be a microwave, x-ray or gamma ray.

The explantion you gave me about the sun just basically says all the types of waves are produced as one as a spectrum.

Don't get me wrong i am very thankful for the explantion and I did find it most inteeresting, i also think i asked my question wrong.

Thanks again.

Yours Respectfully
Avin Sinanan