Count to 60. By the time you’re done, Earth will have soaked up a lot of sunlight. How much?
Enough to meet the world’s energy needs for a whole year! Sadly, very few people use this energy to power their homes or offices.
One problem is cost. Solar equipment makes power for about the same price as the electric company. But setting up solar panels and other gear can be complex. Costs start around $10,000. Weather is a problem, too. Cloudy or snowy days produce less solar power.
Even so, many people want to use solar energy. Unlike the Sun, energy sources like oil and coal cause pollution. And one day they’ll be gone.

As the Sun rises, the solar cells produce more power. The batteries produce less.
Solar-powered houses are not new. Around A.D. 1100, the Anasazi people built homes in what is now New Mexico. These buildings collected and used solar radiation. They faced south to draw the most sunlight. Thick stone and adobe walls absorbed heat during the day. At night, they released the heat. ▶


◀ About 0.25 percent of the Sun’s energy gets turned into wind. By the middle of this century, wind could satisfy 10 to 20 percent of the world’s demand for electrical energy. But there’s a big problem with wind power. Like the Sun, it’s unpredictable.
You can see solar power in a greenhouse. The glass lets in light. It also traps it. This lets plants grow in any weather. Earth’s atmosphere works in much the same way. But burning oil and coal releases “greenhouse gases,” like carbon dioxide, into the air. These trap greater amounts of sunlight. That makes the Earth warmer. Some scientists believe this warming could melt polar ice sheets. It could also cause huge changes to our environment. ▼

Check It Out!
Which state calls itself “the Sunshine State”?
Florida. But South Dakota was long known as the Sunshine State.


▲ The Sun and other stars were once the only way for sailors to tell east from west or north from south. Today, the Global Positioning System (GPS) does that job. The GPS is 24 satellites that orbit the Earth. They let people with GPS receivers find their exact longitude and latitude. They can even find their altitude. The Sun is an important part of the GPS. Those satellites are all powered by solar cells.
Too little sunlight can be bad for your health. In far northern countries, winter days are short. This can make people feel very sad. Some people use artificial sunlight to feel better. Too much sun can also be bad for you. Deadly skin cancer rates have gone up a lot in the last 30 years. That’s because more people are sunbathing. They’re also spending more time in tanning salons. ▼
