The document discusses the composition and layers of Earth's atmosphere. It explains that the atmosphere is made up of 78% nitrogen, 21% oxygen, and 1% other gases including carbon dioxide and water vapor. It also notes that particulates from sources like soil, salt, fire ash and pollen are present. The layers of the atmosphere from closest to farthest from Earth are: the troposphere, stratosphere, mesosphere, and thermosphere. The atmosphere helps control the planet's temperature and the greenhouse effect traps heat from the sun, which is vital to prevent the Earth from being too cold to support life. However, too much greenhouse gas can make the planet too hot.