You already know the Sun, that shiny ball in the sky, but have you ever wondered what actually is the Sun? What is it made of? Why does it shine so bright? Or even how old is the Sun? Let’s discover all about it in this lesson.
What is the Sun?
The Sun is a hot ball of glowing gases that gives off great amounts of energy. It is the star at the centre of the solar system. It is a G-type star. The sun is a main sequence star. It is around 4.5 billion years old, and it is in the middle of its life.
All planets, comets, and asteroids in the Solar System orbit the Sun. The Sun and the Solar System orbit around the centre of our Galaxy, the Milky Way.
Structure and Layers of the Sun
The structure of the Sun contains 7 layers. The inner layers are the Core, Radiative Zone and Convection Zone. The outer layers are the Photosphere, the Chromosphere, the Transition Region and the Corona.
1. The Core
The core is the heart of the Sun. It is the innermost, or the internal, layer of the Sun. The temperature and the pressure are so high at the core, which helps the process of nuclear fusion occur. During nuclear fusion, hydrogen fuses into helium. This process releases energy that makes the Sun shine. So, all the heat and light that we feel on Earth started in the Sun’s core through nuclear fusion.
2. The Radiative Zone
It is the layer of the sun in which energy transfer occurs. Energy is transferred in the radiative zone by radiation. The temperature in this layer drops down. rather than by convection.
3. The Convective Zone
In this layer, the gases are not dense enough or hot enough to transfer the energy of the interior layers to the outside by radiation. Instead, energy gets transferred towards the sun’s surface by convection.
4. The Photosphere
The photosphere is the deepest and the brightest layer of the Sun. It is not the outside layer of the Sun, yet it is the layer that we can see from Earth.
5. The Chromosphere
The chromosphere is the layer above the photosphere. In this layer, the further you go away from the sun, the hotter it gets. This is the opposite of the lower layers, where it gets hotter if you go closer to the centre of the sun.
6. The Transition Region
The transition region is a thin layer between the chromosphere and the corona. In this layer, the temperature rises hugely and abruptly.
7. The Corona
The corona is the outer layer of the Sun, and it is much bigger than the rest of the Sun. The temperature in the corona is so high that it can reach up to a few million K. The corona layer cannot be seen with the naked eye from Earth except during a total solar eclipse. This layer is constantly expanding into space forming the solar wind, which fills all the solar system.
20 Interesting Facts About the Sun
- Life on Earth would not exist without the Sun. Life depends on light and heat, and the Sun is the source of all the heat and light that reaches us on Earth.
- The Sun is the largest object in the solar system, and more than a million Earths would fit inside it.
- Although the Sun is the largest object in the solar system, it is considered small in comparison to other stars.
- The Sun is the closest star to Earth, and the next closest one to Earth is Proxima Centauri. Its light takes more than four years to reach Earth. That is why the Sun is the brightest object in the sky.
- Although the Sun is the closest star to earth, its light takes eight minutes and 20 seconds to reach Earth.
- If the Sun disappeared, we would only notice its absence after eight-minutes, because it takes eight minutes for sunlight to reach us.
- The Sun’s true colour is white, but we see it yellow because of the Earth’s atmosphere.
- The Sun rotates from west to east, which is the opposite direction to the rotation of the Earth.
- A solar eclipse occurs when the Moon is between the Sun and the Earth that it blocks sunlight and casts a shadow on Earth.
- The interactions between the Sun and Earth drive the seasons, ocean currents, weather, and climate.
- The Sun fuses about 600 million tons of hydrogen into helium every second.
- The energy in the core of the Sun can take between 10,000 and 170,000 years to escape.
- If you look at the Sun through a special solar telescope, you can see sunspots, which are dark areas caused by the Sun’s magnetic field, and they look dark because the rest of the Sun is very bright.
- Looking at the Sun with the naked eye can cause pain because of its great brightness.
- Partial solar eclipses are very dangerous to view because the eye’s pupil is not adapted to such unusual high visual contrast.
- Ultraviolet light from the Sun can be used to sanitize tools and water.
- Ultraviolet light from the Sun can cause sunburn.
- Ultraviolet light from the Sun has some biological effects such as producing vitamin D.
- The Sun’s hot corona shoots out tiny bits of particles that carry an electric charge, and they are called solar wind.
- The interaction between the solar winds and the Earth’s atmosphere causes the appearance of auroras. Auroras are colourful bands of light that appear in the sky in Earth’s far northern and southern regions.
Why Do We Need the Sun?
The Sun is the most important thing to us on Earth. Since ancient times, people have recognized the great effects of the Sun on Earth. Some cultures worshipped the sun and thought of it as a god. For example, Ancient Egyptians had a sun god called Ra.
Here are 10 reasons why the sun is important:
- The sun provides us with the light that we need to see and do our work.
- The sun provides us with the heat that we need to warm our bodies.
- The windmills depend on the Sun to generate electricity.
- The sun helps in forming fuel that is needed to operate machines.
- The sun provides humans with vitamin D which is essential to the body.
- Sunlight is essential for plants to grow. Plants make their own food through photosynthesis, and the main factor in photosynthesis is the light from the sun.
- Plants make use of sunlight to produce oxygen, and the oxygen is essential to us, humans, to breathe.
- The sun is responsible for changing our weather patterns and climate.
- The Sun’s heat causes the difference in the temperature in some areas, which helps forming winds. Winds are important to move clouds and disperse plant seeds.
- The sun is the main part in forming clouds and the rainfall process. The sun heats the waters, forming water vapour. When water vapour rises in the sky, it cools and forms clouds. Winds move the clouds and when clouds become heavy with water, the rain falls.