Introduction

The sun is the center of our solar system. Without the sun, there would be no life on Earth because it would be cold and dark. The sun was formed by gas almost 5 billion years ago. Why does the earth revolve around the sun? This question was unanswered until Sir Isaac Newton discovered that the sun’s strong gravity pulled the planets to revolve around it.

The sun is the biggest object in the solar system; if the sun was hollow, it could hold a million earths! The sun is a star, but even though it is the biggest object in the solar system, there are some stars that are bigger than the sun. For example, Beetlejuice is a star bigger than the sun, but Beetlejuice is very far away, so it appears to be smaller than the sun from our point of view. Here is some more information on the sun.

Why we need the sun

The sun is not just a star that provides Earth with heat and light. The sun also gives us many other things we need to live. Energy is one example. The sun is the main source of energy on earth and energy produces a lot of things that we use today. Our electricity is generated by burning fossil fuels; coal, oil, and natural gas. These all come from sunlight. Our electricity comes from fossil fuels, which come from the sun because creatures that lived a long time ago needed the sun to live and when they died they were buried. Over the millions of years that passed the creatures turned into fossil fuels, which are the coal, oil, and natural gas, we use today. Even windmills and hydropower plants get their energy from the sun. Windmills move because the sun causes winds to blow. First, the sun’s rays in the form of radiation hit the surface of Earth. The warm ground heats the air above. Warm air at the equator moves north and south to the cooler regions at the poles, creating winds.

Hydropower plants generate energy because the sun causes rivers to flow. The sun causes rivers to flow because the sun creates warm air that gets trapped into some parts of the earth’s atmosphere. Then the warm air heats up the water in the river. Then the part of the river that is not warm hits the warm water and since warm water rises because it is less dense than cold water that creates a circulation that creates winds.

We also need energy to run, jump, and do many other things. This energy comes from the sun, too. The sun is the head of the food chain, because a plant needs the sun to grow. When an animal comes and eats the plant, the energy converts to the animal. Then an animal eats that animal and the energy is passed to that animal. This process keeps on going which is why we have a lot of energy today.

Atmosphere

The sun’s atmosphere contains three visible regions; the photosphere, the chromosphere, and corona. The photosphere is what we usually see of the sun, even though we should never look at the sun. The other two regions can be seen in a total eclipse. The temperature of the photosphere is about 10,000°F which is cooler than what is above and below it. The photosphere is what sends light and heat into space. These waves travel through space at 186,300 miles per second, reaching the earth in a little more than eight minutes. The photosphere is very important because it sends heat and light to earth, which we need to live. The chromosphere is the middle level in the sun’s atmosphere. The only time we can see the chromosphere is when a total eclipse occurs. A total eclipse is when the moon passes between Earth and the sun. At the chromosphere, there are giant tongues of flame called spicules. These are jets of hot gas that shoot from the chromosphere into the less dense area above. The outer layer which surrounds the chromosphere is the corona. The corona extends great distances for millions of miles. The corona is much hotter than the chromosphere. Its temperature is into millions of degrees, but the gases in the corona are very thin. Here is a diagram of the Sun’s outer layers. Note that the photosphere looks like the solar "surface." "Surface" is in quotation marks because the sun is a ball of gas which has no true "surface."

The Core

The core is one of the most important parts of the sun. The core is 27 million degrees Fahrenheit and is about the size of Jupiter. The sun has been glowing for about 5 billion years because of something that occurs in the core, the power of fusion. Fusion is when hydrogen is fused to helium. Energy is released in the form of gamma rays, a type of radiation that is invisible and extremely hot. This process happens tens of trillions of times every second which is why the sun is still glowing.

Sunspots

One of the most interesting features on the sun are its sunspots. Sunspots were noticed by Chinese scientists as early as 28 BC. They thought they were shadows cast by flying birds. Today, with the basic facts we have learned, we know why they are so dark. We know they are not shadows of flying birds, but everyday solar events. They appear dark because they are cooler than the gases around it, but they are still very hot, about 7,000° Fahrenheit. They range from 500 miles in diameter to more than 50,000. They are even big enough to swallow several Earths. An average sunspot can last for about a week, but some can last only for a few hours or as long as 18 months. Beyond these basic facts, scientists do not fully understand where they exist or where they come from.

The sun is probably the most important thing the earth needs. The sun provides us many things including heat and light. The sun also is the reason why there is life on earth. The sun is the star that controls the solar system, almost like the king or queen of the solar system. The sun is a very great star.