Earth
Earth is the third planet from the sun. It can also be referred to as Earth, Planet Earth or Terra. The home to millions of species, including humans, the earth is also the only place in the universe where life is known to exist. Scientific proof has shown that the planet was formed about 4.54 billion years ago, and life appeared on its surface within a billion years. Earth is expected to be 4,600 million years old. The average distance of Earth with the sun is 149.6 million kilometers. The Earth has an air layer and a magnetic field called a magnetosphere that shields Earth's surface from sunlight, ultra-hazardous radiation, and radiation from outer space. This air layer springs up to an altitude of 700 kilometers and the rest is considered as outer space. The air layer is divided into Troposphere, Stratosphere, Mesosphere, Thermosfera, and Exosphere. The ozone layer, 50 kilometers high, exists in the Stratosphere and Mesosphere layers and protects the earth from ultra-violet radiation.