space starts about 60 miles above the surface of earth - how far is space from the surface of venus?

Answer 1

It is true that it's fairly arbitrary where space starts - 60 miles above the Earth is not a hard limit. In fact, you'd never want to orbit at 60 miles since atmospheric drag is still pretty noticable at that height. This is why the shuttle orbits significantly higher, around 200 miles or so.

Venus actually has a *much* thicker atmosphere than Earth does...at the surface it's roughly 100 times the atmospheric pressure of Earth. You'd be instantly crushed by the pressure if you were magically transported there. The thick atmosphere contributes to a wicked strong greenhouse effect, making Venus the hottest planet in the solar system.

Now, planetary scientists use something called "scale height" when talking about how quickly the atmosphere thins out with height. One scale height means that the atmospheric pressure is only 37% as large at the top versus the bottom. On Earth, one scale height is roughly 5 miles, so if you climbed to the top of a mountain 5 miles high - about 26,000 feet - the air at the top would be only 37% of what it is at the surface.

With space at 60 miles, that's 12 scale heights (60/5 = 12). So the atmosphere will have dropped off to 37% raised to the twelfth power, or about 160,000 times thinner that at the suface. That translates to 6 microbars, where 1 bar is the pressure at Earth's surface. Let's say that 6 microbars is where the atmosphere is thin enough to be considered "space". (Incidentally, the super-thin atmosphere of Pluto is around 6 microbars...)

For Venus, the scale height is roughly doubled - ten miles. This is due to a combination of slightly less gravity, hotter temperatures, and what the atmosphere is made of (mostly carbon dioxide). Using Venus' scale height and the fact that the surface pressure is 92 bars, we can solve for how high we need to go up to get to an atmosphere of 6 microbars. We want to decrease our pressure by a factor of 15 million, so we take the natural log of 15 milion and get 16 Venus scale heights. Since a Venus scale height is 10 miles, that's a total of 160 miles above the surface to get to an equivalently thin atmosphere.

The short answer: Assuming "space" lies 60 miles above Earth, "space" lies 160 miles above Venus.

Answer 2

Space is all around us we are space, your referring to planetary atmospheres and how far the gases extend, or even the magnetic fields- but we are floating in space, like a rock in water, space exist through the earth.

Answer 3

it's kind of arbitrary. We define space as the final limits of our atmosphere, so space would start for venus at the outer limits of its atmosphere. I don't think venus has a very big atmosphere (it's proximity to the sun would burn it off). I'm not even sure it has one at all. So space would start much sooner on venus.