Why Do They Say That Outer Space Is Like A Vacuum?

Question

And if it is true, why don't astronauts go flying off into space when they are doing an EVA?

Answer 1

Space is, on average, a vacuum because there is so much space between galaxies, stars, and planets. All of the mass of the universe is caught up in stars (which make up galaxies) and planets. In between are vast, almost unimaginable distances, where there is nothing but a few hydrogen atoms (thus virtually a vacuum) every cubic meter.

Whatever matter was between stars was, over the course of billions of years of cosmic evolution, attracted by gravity to become part of galaxies and stars. So the answer to your question is really two fold:

1) Space is very large and does not contain that much matter so that even if the matter were evenly distributed, the density would be extremely low, close to a vacuum.

2) The attractive pull of gravity makes the matter clump so that there is little matter left between the clumps (for instance between stars). That interclump (interstellar) space therefore is pretty much a vacuum.

BTW...there is gravity in space, tons of it. The reason you get the feeling of weightlessness is because you're in constant freefall.

Answer 2

There is no pressure in space, like a vacuum tube. So when the shuttle opens, all pressure is released into space. The astronauts must go into a depressurization chamber, which will slowly lower the pressure before going out.

Answer 3

a vacuum and zero gravity are two different subjects. Space is almost a complete vacuum AND it has zero gravity. When they are doing space walks, they are being pushed or pulled in either direction. they are just floating. they actually could go flying off into space if they weren't tethered and they pushed off. But that has nothing to do with the vacuum of space.

Answer 4

The vacuum means there is no resistance to slow inertia, so the astronaut keeps up with the Shuttle since they both have the same inertia in the same direction.

Answer 5

because at that altitude there is still gravity,, if the space shuttle slows down from 17000 miles an hour it will come back to earth

Answer 6

There is no air in space. It has no gravity, so the air goes around something that does. (planets and stars)

Answer 7

They say that outer space is like a vacumn becuase it is so vast.

Answer 8

Because it is a vacum, it is void of all matter. I think you may be confused with a vacum cleaner, this kind of vacum just means "void of all matter"