Birth of element III

For example, if we go into a tunnel, we might have experienced the fact that our body all of a sudden look like a dead corpse. That’s because the light used in the tunnel in many of them are based on sodium. They’re called sodium lamps.  What’s going on there, that inside the glass of that lamp or light, we have the gas of sodium in it, and the sodium emits light of very particular color-Yellow. For a given chemical element, we know exactly what color would come out from the chemical element. At the same time, there are only colors that particular chemical elementcan also absorb.

So one element, specify colors, either absorption, or emission. One chemical element implies a very specific set of colors. So once we see these missing black lines in the sunlight we can look at the particular color of these missing lines and say, this is actually iron. This is actually chromium and so on. These missing lines are like fingerprints of chemical elements that exist inside the sun. So by studying these missing lines, we can tell what the sun is made of. So, if we blow it up, you see many of these lines, and we can identify each one of them to a particular chemical element which you can study in the laboratory. For example, this is magnesium; this is sodium, hydrogen, and iron.

 We can see, all of them have lines in different colors in different locations. So knowing these black lines, the absorption lines in the sun, we can tell exactly which line corresponds to which chemical element. But it's not the whole complete story, so when you think about, for example, our Sun, the only thing we can see is the surface of the Sun.

We can't see straight into the interior or center of the Sun directly because light doesn't penetrate through it. That is one of the problems when people asked the question why does the sun shine? 

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