I understand the N2 O2 are very small molecules. But aren’t they all packed down on the earths surface? There’s no vacuum here so all of space on surface level should be filled with N2 C2O and O2
In: Physics
Transparency is not necessarily a function of density or volume of the stuff you are trying to look through.
Water is transparent so is glass and all sorts of other stuff.
Most of the time the “seeing things” for transparent stuff comes from where there is a boundary between one substance and another.
You an see the surface of water, but you can’t really see water as such when you are submerged in it. You are always submerged in air.
Our eyes evolved to be able to see things. So we ended up seeing things in the part of the spectrum where there was both a lot of light and where air wouldn’t be too much of a distraction.
If the part of the spectrum we saw was shifted more in the direction of ultraviolet, we wouldn’t be able to see though glass for example. The microwaves that you use to heat your food go though all sorts of stuff, but are absorbed by water.
What is and isn’t transparent at what wavelength is complicated. Having more of it works most of the time. You can only see so far in water and air starts looking blueish if you stack up enough of it, while thin sheets of normally opaque material can become at least translucent.
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