… silicon, one of the most common elements on Earth. The crystalline silicon solar cell was one of the first types to be developed and it is still the most common type in use today. They do not pollute the atmosphere and they leave behind no harmful waste…

… man-made energy, which is virtually pollution-free and affordable, seems impossible. Although such a concept seems like science fiction today, real efforts are underway to assure that by the late 21st century, what once seemed like a dream, will be…

… Earth depends on energy from the sun. Solar energy is the source of energy for photosynthesis. It provides the warmth necessary for plants and animals to survive. The heat from the sun causes water on the Earth's surface to evaporate and form clouds…

… ENERGY The Sun's rays have long been used as the heat source for evaporating and distilling water. Solar evaporation has always been an important salt-production process. Salt water is pumped into shallow ponds that are open to the Sun. As the water…

… billion stars in our galaxy. diameter: 1,390,000 km. mass: 1.989e30 kg temperature: 5800 K (surface) 15,600,000 K (core) The Sun is by far the largest object in the solar system. It…

… of an alarm clock or the whistle of birds may wake us up in the morning. Through out the day, we hear a variety of sounds; for instance, the banging of pots and pans, the roar of traffic, and the voices of people. When we fall asleep at night, we might…

… Even if you don't live near a rain forest, you still can feel the effects of the rain forest. Take a deep breath. The air you are breathing comes from the rain forests, as they are known as the 'lungs of the world.' Rain forest destruction is a…

… is space colonization. There are three places that I know of that the human race has thought of colonizing . They are: The largest asteroid that is orbiting in our solar system, the Moon and Mars. An asteroid There is an asteroid that is orbiting…

… beginning of mankind, people may have looked up thought nothing of what lay above them. The stars, moons and planets, were just lights in the sky which appeared only in the dark void brought upon by night. Then people thought about what was there,…

… the penetration by humans into the universe above the earth’s atmosphere. The purpose of space flight is to suite the scientific, physical and mental needs of humans. Some reasons/goals for space flight is to provide earth’s communications,…