What Is The Origin Of The Sun?
Centuries ago, the Incas of Peru called themselves “Children of the Sun”, and performed ceremonies in the worship of the king of the heavenly bodies. They were wrong, of course, in thinking that the sun was a god. but they were right in believing that there would be no life on earth if it were not for the sun. If the light from the sun were suddenly cut off, life on earth would be impossible.
But there is really nothing special about the sun. It is just a star. Not the biggest or the smallest, not the brightest or the dullest, just an ordinary star like millions of others in the universe. It happens to be the nearest star to us, and we are at just the right distance from it to make it possible for us to enjoy the benefits of its heat and energy.
Since the sun is a star, scientists cannot really know what its origin was, because they still do not know how the stars in the universe came into being. The invention of the spectroscope revolutionised the study of the sun, by making it possible for astronomers to discover a great many of the elements which go into its make-up. It is now known that nearly all these elements are found in the earth’s crust, too.
Does The Sun Shine The Same All The Time?
You’ve heard the expression: “As sure as the sun will rise tomorrow.” The sun is for us a pretty steady and dependable thing. Whether we see it or not, we know it is always there, shining in the same old way.
And for all practical purposes, that is good enough. The sun is a star, and so it shines by its own light. Where does it get this energy? It is now believed that hydrogen atoms in the very hot interior of the sun combine to form helium. When this happens, it sets free energy which flows steadily to its surface. And the sun should be able to continue radiating this energy for many millions of years to come.
But if we examine the sun in a little more detail, we do not get quite the same “steady” picture. First of all, the sun is not a solid body like the earth, at least at its surface. In fact, different parts of the sun rotate at different rates. The sun’s rate of rotation increases from 25 days at its equator to 34 days at its poles.
The outer layer of the sun, called “the corona”, is composed of light, gaseous matter. The outer part of this corona is white, and it has streamers that extend out millions of miles from the edge of the sun. These may cause small, but definite differences in the way the sun shines.
Another layer of the sun, called ” the chromosphere”, is about 9,000 miles thick and is made up largely of hydrogen and helium gas. From this there project, huge clouds called “prominences”, which may rise to heights of 1,000,000 miles. These also are part of the “unsteady” way the sun shines.
How Hot Is The Sun?
It is rather hard for us to realize that our sun is merely just another star in the sky. This is probably because we think of the stars as looking so tiny. The sun looks larger than any star because it is only about 93 million miles from the earth. The nearest star is 25 billion miles away!
What is the temperature on the surface of the sun?
Scientists believe that it is about 6,000 degrees Centigrade. To give you an idea of how hot this is, white-hot molten iron used in making steel reaches a temperature of about 1,430 degrees. So you see how much hotter the sun’s surface is. And as for the interior of the sun, astronomers estimate it may be as hot as 20,000,000 degrees centigrade.
Remember, scientists, are only making a “guess” about this because we know almost nothing about the interior of the sun. We do know something about the composition of this star. For example, it has been learned that the sun contains more than 60 of the chemical elements present in the earth. But it is hard to study the sun’s interior because the sun is surrounded by four layers of gaseous matter.
How can we even think about the sun in this way? Won’t the sun last forever? The reason science can consider this question is that we know the sun is simply a star, and this means we can compare it with other stars. And since other stars have gone through a process of change, science believes that the same will eventually happen to the sun.
At one time, in fact, it was believed that the sun was a body that was slowly cooling off. It was simply “burning”. Now we know that if this were so, the sun should not have lasted several thousands of years.
If it is not “burning”, then what is going on in the sun? We now have evidence that indicates that the sun ‘s radiant energy is the result of atomic transformations. The hydrogen atoms in the very hot interior of the sun combine to form helium. This sets free the energy flows steadily from the inside of the sun to its surface.
How long can this go on? Well, let us suppose it goes on exactly as it is doing now for another 150 billion years. As a result of this process, the mass of the sun would be reduced by roughly 1 per cent! So it seems that the sun can continue to shine and supply the earth with energy for many billions and billions of years to come.