Final answer:
The atmosphere is mainly composed of nitrogen and oxygen. It is divided into five layers: troposphere, stratosphere, mesosphere, thermosphere, and exosphere. Additionally, the atmosphere protects the Earth from harmful radiation.
Step-by-step explanation:
The atmosphere is the gaseous layer that surrounds a planet. Earth's atmosphere is mostly made up of nitrogen (roughly 78.1%) and oxygen (approximately 21.0%). The atmosphere is divided into five layers: the troposphere (up to 12 km above sea level), the stratosphere (12-50 km), the mesosphere (50-80 km), the thermosphere (80-700 km), and the exosphere (furthest from the Earth, > 700 km above sea level).
The atmosphere is responsible for protecting the Earth from harmful radiation such as ultraviolet (UV) rays. The ozone layer, located in the stratosphere, absorbs UV-B rays, preventing them from reaching the Earth's surface and causing skin cancer and genetic damage. The atmosphere also plays a crucial role in regulating the Earth's temperature and supporting life on the planet.