People once believed that Earth was the center of the solar system. Scientists finally learned that Earth is one of at least eight planets in our solar system and that they all travel around the sun. Astronomers now know that our solar system is almost 5 billion years old and is part of at least 100 billion galaxies in the universe. Earth is the only planet known to have life and water. Scientists continue to discover new planet-like objects, called dwarf planets, all the time!
Long ago, astronomers believed that the Earth was the center of the universe. But now we know that it is only a tiny part of the universe and that our solar system is just a tiny part of our galaxy. In 1957, space travel began. Work done in space has helped us in the areas of medicine, computer science, and the environment. The International Space Station, a lab floating in space, is where astronauts do experiments that help us on Earth. The next manned trip to the moon is planned for 2018.
Earth is made up of atmosphere that protects us from the sun and contains our air supply. The next part is the hydrosphere, which is all the water on the planet. The third is the geosphere, the rocks. All three parts are closely connected. If we do not take care of one part of Earth, such as the ocean, we hurt the entire planet. Scientists all over the world are working to find ways to reduce pollution and make our Earth healthier.
Light and sound are two of the most important ways to understand the world around us. The sun is Earth's main source of energy and light. Light bounces off objects and travels to our eyes. Our eyes and brain work together to translate that light into what we see while our ears pick up sound vibrations and translate them into meaningful messages.