LayersThe atmospheres of each of the planets is made of layers. The atmosphere of the Earth is divided into five layers. The atmosphere of Mars is divided into only three layers. The first layer on Mars, the troposphere, is twice as large as the first layer of the Earth's atmosphere.
The middle of the atmosphere is called the mesosphere. The temperature of this layer is usually the coldest part of the atmosphere.
The very top of the atmosphere is called the exosphere. Temperatures in this region are very hot!