The Atmosphere
The atmosphere is made of gas molecules, nitrogen (78%), oxygen (21%), argon (1%) and sometimes water (0 to 7%). There can be more water in the atmosphere near the ocean, or after it rains.
The atmosphere gradually thins out into space. The atmosphere is the thickest near the earth.
There are 5 principal layers in the atmosphere, the first layer is the troposphere that is where the weather is made, then comes stratosphere which is where planes fly. The ozone layer is inside the stratosphere, next is the mesosphere that is where rocks burn so that they do not hit the earth, the second last layer is the thermosphere which is really thin, space ships fly in this layer, the last layer before space is the exosphere.
There is lots of other things in the atmosphere including salt, that comes from the ocean, dust that comes from volcanoes and pollution.
Here is a graph of the 5 layers of our Atmosphere:
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