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
There’s a lot of air, yes. But it doesn’t really interact with air that much at all. For you to be able to see an object or matter it has to reflect light and absorb some of the light to create color.
Like, you know how white is made of red, green, and blue? Lets say you have a red brick, it gets hit by white sunlight, it absorbs the green and blue, and bounces the red light back at your eyes. That’s how you see a red brick. The more of the light it bounces off, the better you see it.
But then there are some things that are transparent. They reflect some of the light, but they also allow some light to go through. Like glass or water, for example. You can see glass and water because they reflect a small amount of light (and because the dirt on or in them reflects a bit too), but you can still look through them for the most part, and see stuff behind or inside of it. And in this case glass is a lot more transparent than water. (it interacts with the light less) because you can see pretty much as far as you want through and inside of good quality glass, but you can only see a small distance through water, because it’s less transparent, and if you have enough of it, it will eventually absorb all of the light, letting you see nothing.
Air, on the other hand, is extremely transparent. It barely interacts with the light at all. So it doesn’t reflect enough light for your eyes to be able of detecting it. But there is, however, indeed a lot of air, so it is possible to see the effect. This is the sky being blue, and the stars being invisible during the day. That’s all that air in the atmosphere reflecting the tiniest amount of blue light down at you from the sun to make the sky look blue, and enough to drown out the light of the stars.
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