Space Systems: The sunBy Encyclopaedia Britannica, adapted by Newsela staff

Grade Level 203/29/2017

Word Count 412

A flock of blackbirds fly against the sunset at a wildlife refuge in Kansas. Photo from: Wikimedia Commons.

The sun is a star. It is the closest star to Earth. The sun is very important to Earth. It

gives Earth almost all of its energy. Energy is what makes things work. It powers

computers and makes cars run. 

The sun gives the Earth light and heat. Without this energy, there would be no life on

Earth.

The sun is special to us. But it is a pretty ordinary star. Like other stars, it is a huge

ball of hot gases. It makes huge amounts of energy.

The Sun And The Solar System

The sun and planets of our solar system. Image from: Wikimedia Commons.The sun is

at the center of our solar system. The solar system is the sun and everything around it.

It includes all of the planets. It also includes their moons.

The sun makes a huge amount of gravity. This is a mysterious force. It helps shape

the universe. Gravity keeps the planets circling the sun. On Earth, it makes apples fall

from trees. It keeps people stuck to the ground.

Stars Come In Many Sizes And Colors

Stars come in different sizes and colors. Some are very large. They are called giant

stars. Others are much smaller. They are called dwarf stars. 

Stars that are very hot are pale blue. Stars that are colder are red. The sun is a yellow

dwarf star. It is medium-sized. Still, it is much bigger than Earth.

The sun is not a solid. It is a ball of very hot gases. It is mostly made of two gases:

hydrogen and helium.

The Sun Makes Energy

U.S. astronauts took a photograph from space of a huge flare of energy on the sun.

Photo from: NASA.Energy is made in the center of the sun. This part is called the core.

The core is very hot. It heats up the sun's gases. The gases are made of tiny particles.

They bounce around inside the core. Sometimes they join together. This happens when

it is very hot. It makes the gases release energy. They give off light and heat. 

There are two main forces inside the sun. One is gravity. The other is the sun's energy.

The sun's gravity pulls the sun in. The sun's energy pulls the sun out. 

If gravity was stronger, the sun would get smaller. If the sun's energy was stronger,

the sun would get bigger. Right now, they are equal. So the sun stays the same size.