Earth’s atmosphere protects life on the surface by filtering deadly ultraviolet radiation, destroying most meteors that pass through it and retaining heat. The atmosphere also provides oxygen to humans and carbon dioxide to plants.
The atmosphere consists of five layers and is approximately 60 miles thick. The layer closest to the surface is called the troposphere, and it provides the majority of the planet’s oxygen. This layer is also responsible for weather, including rain, which protects Earth's inhabitants from drought and starvation. Above the troposphere is the stratosphere. This contains the ozone layer, which absorbs harmful radiation. The stratosphere has very stable weather, which makes it safe and ideal for aircraft.
The middle layer is 20 miles thick and is known as the mesosphere. This layer is where most meteors either shrink or burn up completely. The second-highest layer of the atmosphere is the ionosphere, and this extremely thin layer extends into outer space. This layer is important for communication, as satellites orbit in this layer, and radio waves bounce off it. The outermost layer of the atmosphere is known as the exosphere. This layer protects the planet from solar wind, which exerts force against it and determines its size. The size ranges anywhere from hundreds to thousands of miles above the earth’s surface.