How the sun was born

Most scientists think our sun began as an immense cloud of gas and dust.

Stars that are growing old often shoot out enormous clouds of gas and dust. The gas and dust are made up of all kinds of chemicals. There are many such clouds in space. As these clouds move through space, they pull more and more gas and dust into themselves.Gravity pulls all the gas and dust together, tighter and tighter. Over many millions of years, the center of the cloud of gas is pulled into the shape of a gigantic ball.

Gravity squeezes this gas ball together so tightly its center is more dense than steel ! When gas is squeezed together that tightly, it becomes tremendously hot. The center of the gas ball grows so hot that it becomes an atomic furnace. The ball begins to glow with this fierce heat. It has become a star !

This is how all stars seem to form. Right now, out in space, new stars seem to be forming out of clouds of gas. And scientists think this is how our own sun began, about five billion years ago.

The bright giant

Millions of miles (kilometers) out in space there is a gigantic ball of hot, glowing gas we call the sun.
The sun is actually a star. It is the closest star to us. Its official name is Sol, which was the name of the ancient Roman sun god. From the name Sol comes our word solar, which means "of the sun".

The sun is enormous ! At least 1,300,000 planets the size of earth could be packed into it. And there would be room left over. And yet, big as the sun is, many other stars are much, much bigger.

Although it is big , the sun looks small. That's because it is so far away. It is about 93 million miles (150 million kilometers) from the earth. It takes light from the sun about 8 minutes and 20 seconds to cross that enormous distance and reach our world. And light is the fastest moving of all things.

The sun is tremendously hot. The hotter a thing is, the more brightly it glows, The sun glows so fiercely that we can't look straight at it. even though it is so far away. But the sun is not actually burning. It isn't a ball of fire. It's a ball of gas, squeezed together so tightly that its center is actually solid. This makes the center tremendously hot. It is really a kind of giant atomic furnace in which the temperature is about 27 million degrees Fahrenheit (15,000,000 degrees Celsius) !

Energy pours up from inside the sun to the surface. The surface is a boiling, bubbling mass from which great spouts of glowing gas leap up - sometimes as much as a million miles (1,609,000 kilometers) into space !

The black emptiness

Space is - emptiness.

It is black because emptiness has no light of its own. It is neither cold nor hot because emptiness has no temperature. And, of course, there is no air or water in space.

But although space itself is emptiness, there are things in it. There are billions and billions of stars. There are huge clouds of gas and dust. Comets and chunks of rock called meteoroids rush through parts of space. Waves of light from stars travel through it. Tiny, invisible particles move about. Space is the emptiness that surrounds all these things.

Space and all the things in it make up what we call the universe. We do not know how big the universe is, but the things farthest away that we know about are very far away. The light they give off takes thousands of millions of years to reach us ! Perhaps the universe stretches away in all directions, forever - and never ends !