The easy way to use energy from the sun

Have you ever walked barefoot across a lawn and then stepped on a black road or sandy beach? 

The heat you felt was from solar energy!

These uses are "passive". That means you don't have to do anything special to collect and use the sun rays. You just have to put yourself where the sun is and let it shine.

What the sun does for us

During the winter in Michigan, the sun shining into the house can warm it up. But, in the summer, you don't want that extra heat in the house. There are two easy ways to make this happen.

Trees like maples, oaks and birches lose their leaves in the winter. We call them deciduous trees. If you plant a tree like that on the south side of your house, it will provide shade in the summer and block the sun from shining into your house and into your windows. In the winter, when the leaves fall, the sun will shine in. Great arrangement, eh?

You can also design the house to have the same result by putting on an overhang.

Because the Earth is tilted on its axis, the sun is lower in the sky in the winter and higher in the summer. The overhang lets the sun's rays in when you need them in the winter, but keeps them out in the summer.

How the sun works

The sun is like a hydrogen bomb 860,000 miles across. It is so hot in the sun and the gravity is so strong that the hydrogen molecules smash into each other.  

When these molecules smash into each other, the two hydrogen molecules, H2 come apart and  become H+  H+, each one having a positive charge. 

Lots of these collisions happen at once, and four loose H H H H atoms join and become helium, He. The process gives off lots of heat, which comes boiling out of the sun as radiation. We see this radiation as light and we feel it as heat.

In our sun, there are trillions and trillions of hydrogen atoms turning into helium every second. These explosions have been going on for billions of years. Scientists believe that there is enough hydrogen in the sun to keep going at least 8 billion more years. That's good because we cannot live with out it. 

How do we use the sun? It keeps us warm.

Green plants use the sun to split water into hydrogen and oxygen. They combine the hydrogen with carbon dioxide to make all of the food for the plant—and for lots of other animals that eat plants.

Plus, plants give off oxygen, which we breathe. We can't live without it!

All energy is solar

Green plants, which depended on the sun, lived and died many million years ago and have been turned into coal, which we burn in our factories.

Tiny animals that lived in the sea eating even tinier sun-dependent plants died and turned into oil and natural gas.

What about wind energy?

That's not solar! Or is it? 

The sun heats the earth's atmosphere unevenly. Air flows from colder areas to warmer areas—that's the wind blowing. So even wind energy comes from the sun. 

The Hoover Dam

How about hydroelectric power? That's made possible by the sun, too. The sun evaporates water from the oceans and other places. The vapor in the air condenses into clouds. Rain falls on the land and runs into the rivers. We build dams to capture the water's energy. This can't happen without the sun.

The image to the left is an illustration of the Hoover Dam. The Hoover Dam provides generation of low-cost hydroelectric power for use in Nevada, Arizona, and California. It alone generates more than 4 billion kilowatt-hours* a year—enough to serve 1.3 million people. From 1939 to 1949, Hoover Powerplant was the world's largest hydroelectric installation; with an installed capacity of 2.08 million kilowatts, it is still one of the country's largest.

* A kilowatt-hour is a unit of work or energy equal to that done by one kilowatt of power acting for one hour. A kilowatt is 1,000 watts or 1.34 horsepower

Fun Fact!  (E=Energy)

E in all coal on earth + E in all oil on earth + E in all natural gas on earth = 1/130 of the total amount of energy reaching the earth in the form of sunlight every year!