Atmosphere
The atmosphere has four layers. The first layer is the troposphere is where we live, where all the weather appears and is visible from space, and where airplanes fly. Then the second layer is the stratosphere which has low levels of oxygen, only the lowest bit of it is visible from space, it starts at an altitude of 10 kilometers above sea level, it is where weather balloons fly, it is home to the ozone, and it gets warmer the farther you go up. The third layer is the Mesosphere (Meso = Middle) there is not much known about this layer, it is to high for weather balloons and too low for satellites but gets colder the farther you go up. The final/fourth layer is the thermosphere and the farther you go up the hotter it gets, it goes up to 70 degrees Celsius. The Thermosphere is split up into 2 parts, the Ionosphere and the Exosphere the Ionosphere is home to the northern lights and why radio waves through satellite is possible, the exosphere is where space stations are stationed and where the atmosphere merges into space.
