Let's get to know the sun. The sun is a star at the center of our solar system. Its gravity holds everything in the solar system together. The sun is a huge ball of gas, mostly hydrogen and helium. It is a yellow dwarf, a medium-size kind of star. It is about 100 times wider than Earth. It would take 1.3 million Earths to fill it. That is a lot of Earths.

The sun is about 93 million miles from Earth. That is a very long way to go. Its light takes about 8 minutes to get here. Besides light, the sun gives off heat. Its light and heat warm Earth and make life possible. Nothing could live on the sun, but its energy is vital for most life on Earth. So, here is a rule to keep. Never look directly at the sun without special eye protection made for it.

Where does all of that energy come from? Let's go inside the sun and see. Deep in the sun's core, nuclear fusion turns hydrogen into helium. This is what makes the sun's energy. The core is about 27 million degrees Fahrenheit. That is much hotter than the surface of the sun. Next, let's see what is on the outside.

The sun is not a solid ball, and you could not stand on it. The part we call its surface is the photosphere. It is about 10,000 degrees Fahrenheit. The sun also has an outer atmosphere called the corona. You might think the surface is the hottest part of the sun. But the corona is much hotter than the surface.

The sun also sends out a steady stream of charged particles. This stream is called the solar wind. It fills the heliosphere, a huge bubble of charged particles around the solar system. Here on Earth, auroras happen when charged particles collide with the upper atmosphere of Earth. So the sun reaches a very long way out into space.

Words to know

• photosphere: the sun's surface
• corona: outer atmosphere
• heliosphere: a huge bubble
• auroras: sky lights

The short version

The Sun is a star at the center of our solar system. It is a huge ball of gas, mostly hydrogen and helium, about 100 times wider than Earth. Its light and heat warm Earth and make life possible, and it also sends out a steady stream of charged particles called the solar wind.

Quick facts

• The Sun is about 93 million miles from Earth, and its light takes about 8 minutes to reach Earth.
• The Sun's core is about 27 million degrees Fahrenheit, and its surface is about 10,000 degrees Fahrenheit.
• The Sun's energy comes from nuclear fusion, which turns hydrogen into helium deep in its core.
• The corona, the outer part of the Sun's atmosphere, is much hotter than the Sun's surface.
• Auroras happen when charged particles collide with the upper atmosphere of Earth.