I’m having a hard time understanding this. From what I have read, a vacuum is a space that is devoid of matter. But there is matter in Space (planets, chemical compounds, stars, etc.). There is something I’m missing here and I’m not understanding
In: Physics
I think maybe there is some confusion between the definition of “space” and “vacuum.”
The word “space” doesn’t *specifically* refer to the emptiness between the planets and stars. “Space,” in the astronomical sense of the word, refers to the three dimensional place in which things exist. It’s all “space.” You’re in space right now.
The distinction is that **most of that “space” is in** ***vacuum***. “Vacuum,” loosely refers to “space” that doesn’t contain matter. I say “loosely” because a perfect vacuum is a very rare thing. For a vacuum to be perfect, the designated space has to be devoid of *all matter particles and protons.* That’s impossible to do experimentally.
Space has an average of 1 atom per cubic centimeter. It’s important to remember that that number is an average, so there are areas of space that contain *much less* than that (like in deep intergalactic space,) and areas that contain *much more* than that (like in-between the planets in our solar system.)
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