The smallest particle into which an element can be divided and still have the properties of that element is called an atom.

a lot of it means it can be "burned" for energy and sold at one price. if it is scarce, the price will go up

as we know our atmosphere or air have different levels. every level has other gasses, and every gas has another permeability. when the light comes from lower permeability to higher permeability, it changes its direction. so that means that when the light comes from the moon to the earth, it changes it's direction many more times. it basically means that the shape of the light part of the moon is changed on the earth.

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