Ngtjyty

The vacuum of space is incredibly powerful
1 X 10 ^-17 torr

I’m editing my question to reflect the vacuum between the earth and the moon 1 X 10 ^-11 torr

How can such a vacuum in close proximity to the earth coexist with the open system of earth’s atmosphere whereby debris from space can enter in?

Apparently according to uhoh the vacuum of space has a gradient. I wonder how that proports to the second law of thermodynamics.

• https://www.raclub.org/Documents/Programs/VACUUM.pdf




• https://web.pa.msu.edu/courses/2014fall/PHY451/Lectures/Vacuum.pdf

update: This answer was written before the question was modified. I've tried to explain where a value like 10-17 Torr for deep space might come from, but it's since been dropped in lieu of 10^-11 Torr at the Moon, which is probably a better way to formulate the question.

I think the answer is the same, two points very far away can have very different pressures. They can coexist in the same solar system, just not right next to each other. I think "Why doesn't the Moon have at least a small atmosphere?" could also be an excellent, but very different question.

In a comment the OP links to the presentation VACUUM (There’s nothing to it… ) written from the perspective of an engineer in the semiconductor manufacturing industry.

Slide 6 gives examples of vacuum levels in different situations:

Going down:

• Low vacuum: 760 Torr to 1 x 10-3 Torr
  
  
  
  
  • Vacuum cleaner: to 600 Torr
  
  
  • Thermos bottle 10-3 Torr
  
  
  
  


• High vacuum: 10-3 to 10-9 Torr
  
  
  
  
  • Electron microscope
  
  
  • Ion Implanter
    – Evaporator
    – Sputterer
  
  
  
  


• Ultra high vacuum: 10-9 to 10-12 Torr
  
  
  
  
  • CERN LHC: 1 x 10-10 Torr
  
  
  • Moon’s surface: 1 x 10-11 Torr
  
  
  • Deep Space 1 x 10-17 Torr = 0.000,000,000,000,000,01 Torr
  
  
  
  

So we can see that the value of 1 x 10-17 Torr is associated with a place in "Deep Space" which is (probably) beyond that of the Moon.

Let's see if we can figure out where the author is getting that number.

According to the Wikipedia article on the interstellar medium (space between stars, far away from solar systems and other things):

In all phases, the interstellar medium is extremely tenuous by terrestrial standards. In cool, dense regions of the ISM, matter is primarily in molecular form, and reaches number densities of 106 molecules per cm3 (1 million molecules per cm3). In hot, diffuse regions of the ISM, matter is primarily ionized, and the density may be as low as 10−4 ions per cm3. Compare this with a number density of roughly 1019 molecules per cm3 for air at sea level, and 1010 molecules per cm3 (10 billion molecules per cm3) for a laboratory high-vacuum chamber.

It is harder to talk about pressure than density because pressure is related to both number density and temperature. The atmosphere is more than 10x hotter than interstellar medium, so let's look for a number density ratio of 1/10 of 1000 Torr versus 10^-17 torr, or a ratio of 10^19.

If (according to Wikipedia) Earth's atmosphere has a density of 10^19 per cm^3, we're looking for a density of 1 per cm^3. Checking Wikipedia we can see that there are components of the interstellar medium with number densities between 10^6 and 10^-4.

It looks like the value in the presentation a rough ballpark estimate, but isn't off by more than a handful of orders of magnitude ;-)

How can such a vacuum coexist with the open system of earth’s atmosphere whereby debris from space can enter in?

While these two pressures can coexist in the same universe, they don't coexist in proximity at all. The interstellar medium is very, very far away from Earth's atmosphere, on the order of a lightyear.

Gravity keeps Earth's atmosphere nearby Earth, the solar system has gas produced by (and attracted by) the Sun's gravity. In interstellar space, there just isn't any source of gas, and what might have been there at one time has moved away, towards sources of gravity, over billions of years.