Definition
The mesosphere is the third layer of Earth's atmosphere, located above the stratosphere and below the thermosphere. It extends from about 50 to 85 kilometers (31 to 53 miles) above the Earth's surface. This layer is characterized by decreasing temperature with increasing altitude; it's the coldest part of the atmosphere, reaching temperatures as low as -90°C (-130°F). Meteors burn up in the mesosphere, creating shooting stars. Think of it as Earth's natural shield, protecting us from space debris.