What is the average distance from any point on the Earth's surface to the outer limits of the atmosphere ?

Question

I mean the point or layer, where space starts?

Answer 1

It's not far. Only a few miles. Look it up.

Answer 2

The short answer is 100 kilometers.

The long answer is that there is no defined edge to the atmosphere; it just gets thinner and thinner for thousands of miles until you can't tell the difference between the Earth's atmosphere and the solar wind. The 100 kilometer altitude is an unofficial definition of how high you need to go to be considered in outer space. Another unofficial definition is 50 miles, which is a little lower that 100 kilometers. The international space station, Hubble space telescope and many other satellites are orbiting well above 100 kilometers but are still in the very thin upper atmosphere, so they experience some drag and will eventually spiral down out of orbit if not boosted back up by rocket power every few months or years.

Answer 3

If the Earth's atmosphere has no definite boundary, then we can't calculate distance from the Earth's surface to the atmosphere.

Main article: Earth's atmosphere
The Earth's atmosphere has no definite boundary, slowly becoming thinner and fading into outer space. Three-quarters of the atmosphere's mass is contained within the first 11 km of the planet's surface. This lowest layer is called the troposphere. Further up, the atmosphere is usually divided into the stratosphere, mesosphere, and thermosphere. Beyond these, the exosphere thins out into the magnetosphere (where the Earth's magnetic fields interact with the solar wind). An important part of the atmosphere for life on Earth is the ozone layer.

The atmospheric pressure on the surface of the Earth averages 101.325 kPa, with a scale height of about 6 km. It is 78% nitrogen and 21% oxygen, with trace amounts of other gaseous molecules such as water vapor. The atmosphere protects the Earth's life forms by absorbing ultraviolet solar radiation, moderating temperature, transporting water vapor, and providing useful gases. The atmosphere is one of the principal components in determining weather and climate.

Because hydrogen gas is light and based on Earth's mean temperature, achieves escape velocity, unfixed hydrogen leaves the Earth. For this reason, the Earth's environment is oxidizing, with consequences for the chemical nature of life which developed on the planet.

Answer 4

There isn't any point or layer really, it just keeps on getting thinner and thinner. About 80 miles up (about 130 km) it's still thick enough to get meteor trails from really fast meteoroids but not thick enough for use as a fuel in a scram-jet - you could put a satellite at a 130km orbital altitude but atmospheric tides would slow it down pretty quickly. Up at the ISS altitude even at high tide the atmosphere is pretty thin and drag effects are small so they don't need to do much orbit raising even though this is a big structure : They still get quite high concentrations of monatomic oxygen though which causes a bit of a long term problem for erosion of surfaces. Even further up there is a high enough plasma density to limit the voltages that you can safely use on solar arrays.

Best of Luck - Mike