Our sun and other stars release light energy. At least this is what we see. Our Sun and stars also emit more than just light. Scientists call the type of energy that our Sun and stars release electromagnetic energy. This form of energy travels through space. Electromagnetic energy includes the light we see. It also includes much more. Many of these things we know about, but dont always think about. Electromagnetic energy includes radio waves, microwaves, and X rays. We now have devices in our homes and offices that release these same forms of energy. We use electromagnetic energy to make our lives better.

Why do we use radio waves, microwaves, and X rays?

If you build a campfire, you start with a large stack of sticks and logs. As the fire burns, the stack slowly shrinks. By the end of the evening, all that is left is a small pile of ashes. What happened to the matter that you started with? Was it destroyed by the flames? It may seem that way. What do you think happened? The truth is that the same amount of matter still exists. The wood changed not only to ashes, but also to carbon dioxide, water vapor, and other gases. The gases floated off into the air, leaving behind just the ashes. Although matter was changed, it was not created or destroyed. Because the same amount of matter still exists, we can say that matter is conserved. You may wonder how it can be conserved if something is now missing? Assume you had measured the mass of the wood before you burned it. Assume you had also trapped the gases released by the burning wood and measured their mass and the mass of the ashes. What would you find? The ashes and gases combined have the same mass as the wood you started with. This example illustrates the law of conservation of mass.

Ashes and gases in an example of what?

For thousands of years, people have found fossils. The fossils caused curiosity about Earths past. How did these organisms live? What type of world did they live in? Fossils can tell us a lot about Earths history. In ancient times, fossils inspired myths and stories. These stories included tales of monsters and other incredible creatures. What type of creature do you know that could inspire such stories? Of course, dinosaur fossils were once mistaken for dragons bones. Two thousand years ago, people discovered fossils in China. At the time, they were thought to be dragon bones. We know now that these were not bones, but fossils. So what is the difference?
What did these stories consist of?