The sun is the closest star to the Earth. Even at a distance of 150 million kilometres (93 million miles), its gravitational pullholds the planet in orbit. It radiates light and heat, or solar energy, which makes it possible for life to exist on Earth.
Plants need sunlight to grow. Animals, including humans, need plants for food and the oxygen they produce. Without heat from the sun, the Earth would freeze. There would be no winds, ocean currents, or clouds to transport water.
Solar energy has existed as long as the sun—about five billion years. While people have not been around that long, they have been using solar energy in a variety of ways for thousands of
years.
Solar energy is essential for agriculture—cultivating land, producing crops, and raising livestock. Developed about 10,000 years ago, agriculture had a key role in the rise of civilisation. Solar techniques, such as crop rotation, increased harvests. Drying food using sun and wind prevented crops from spoiling.
This surplus of food allowed for denser populations and structured societies. Early civilisations around the world positioned buildings to face south to gather heat and light. They used windows and skylights for the same reason, as well as to allow for air circulation. These are elements of solar architecture.
Other aspects include using selective shading and choosing building materials with thermal mass, (meaning they store heat), such as stone and concrete. Today, computer programs make applications easier and more precise.
Shrruthiy Priyadarshan.
Grade 9
Bt/ Vincent Girls’ High School.
Batticaloa.