The Light of the Sun

We love sitting in the sun and feeling its warm rays on our skin. It’s good for our bodies and our souls. We also love being by the sea or on a mountain in the evening and watching the sunset. But we also know that spending too long in the sun can cause sunburn or even serious skin diseases. We would not exist without the sun. The sun itself is much larger than Earth and unimaginably hot. What matters is that Earth orbits the sun at just the right distance. If it were closer, it would be too hot; if it were farther away, it would be too cold. That distance is about 150 million kilometres.

It all began about 4.6 billion years ago. Back then, where the Sun and its planets are today, there was a huge cloud of hydrogen and dust. The cloud gradually contracted under the force of gravity.

A celestial body formed, consisting mostly of gases, especially hydrogen and helium. The gases came together to form a giant sphere. The pressure inside rose enormously, and it grew hotter and hotter.

At some point, a process called nuclear fusion began. Since then, millions of tons of hydrogen have been converted into helium every second. This celestial body has been giving off light and heat ever since. We call it the Sun.

Temperatures on the Sun are higher than anything we know on Earth. At the surface, the temperature is about 3,500 to 5,500 degrees. Inside, it rises to more than 15 million degrees. The Sun releases enormous amounts of energy, which pushes outward and radiates into space. We distinguish between heat rays and light rays. They make it bright and pleasantly warm on Earth, even though we are so far from the Sun. The light rays emitted by the Sun travel away from it at a speed of 300,000 kilometres per second. Even so, they take a little over eight minutes to reach Earth. So we always see the Sun as it was a little while ago.

Because the Sun is made of gas, it has no solid surface. Some areas of its surface are slightly cooler than others. They appear darker in pictures and are called sunspots. Every eleven years, particularly many sunspots can be seen. The tremendous force of energy pushing outward from the Sun’s interior repeatedly hurls huge masses of gas thousands of kilometres into the sky. These explosions are called prominences. Some gas particles are accelerated so much that they escape into space. This creates the solar wind. It also reaches Earth and, for example, causes the aurora. This wonderful glow in the sky occurs when particles of gas from the Sun collide with Earth’s atmosphere.