It was the German physicist Hermann Helmholtz and the British physicist William Thompson, better known as Lord Kelvin, who came up with a new idea. They assumed that the sun received its energy from the fact that it kept contracting. The resulting pressure ensures that the temperature in the sun rises steadily. This energy would even be sufficient for many millions of years but the sun is now around 4.5 billion years old. Helmholtz and Thompson were ennobled for their scientific merits. If they had been right, the sun would not have existed in their lifetime.
Sun is an inverted nuclear power plant
In order to get on the right track, a discovery of the 20th century was required, namely nuclear power. It is a basic force in physics. The name of the force that makes the sun shine correctly is Nuclear Fusion. It is the same nuclear power that also works in nuclear power plants only in the opposite direction. Because in nuclear power plants, atomic nuclei are shattered but in the sun, the nuclei are combined.
With the help of nuclear power, the scientists can explain exactly what is going on in the sun. The sun derives its energy from the fusion of hydrogen nuclei to helium. The forces that act in the hydrogen nuclei are greater than those in the helium nuclei. Excess energy is thus created during the fusion and the difference in forces is released into space. Of course, part of this energy is needed to keep the whole process going.
A combustion like the summer campfire does not take place on the sun. With fire, heat and energy are also released however, through the reaction with oxygen. In technical jargon, this chemical combustion is also called Oxidation.
In the beginning was – gravity
It is a nuclear fusion that releases its energy into space eight light minutes away from Earth. A fusion needs an incredible amount of energy to get started and eventually become a chain reaction.
This is where Lord Kelvin and Helmholtz come in again. Their theory does not explain why the sun still shines today. But she explains how it all started. Pressure and gravity caused the temperature in the sun to rise so much that the hydrogen atoms could combine to form helium.
Future of the Sun
Though the amount of hydrogen in the sun is unimaginably large, this matter will be used up at some point in the future. If the supplies fall below a certain amount, the balance of our home star will begin to falter. The sun will then produce less energy and collapse. As a result, the gravity and pressure will rise again until a new nuclear fusion is initiated. It would be a nuclear fusion of helium, of which the sun has built up a generous supply over the past few billion years. The whole process will go on for a while but mankind will no longer experience this process on the blue planet because the sun will expand due to reduced gravity and will swallow the inner planets.
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