How far from the Earth’s surface does space begin?

Yurima Celdrán Weather Spain 5 minutes
The atmosphere is divided into five layers based on the change in temperature with altitude.

The atmosphere is the thin layer of gases that surrounds our planet and supports life on it. Its main functions include; protection from the sun’s rays more harmful, water vapor and energy distribution, protection from meteors and maintaining the Earth’s temperature.

this thin layer It consists mainly of nitrogen, oxygen and argon., but in recent years it has been affected by anthropogenic activities. These were injected in huge quantities greenhouse gases in our atmospherewith the result that the infrared radiation emitted by the Earth does not escape to the outside and returns, again, to its surface, increasing the temperature of our planet.

If these greenhouse gases did not exist, the average temperature of our planet would be -32ºC when it is actually 15ºCa value that increased in 2022 by +1.1ºC due to the excess of these gases.

In turn, Our atmosphere is not completely homogeneous and is divided into different layersdepending on its chemical composition and physical properties, and is finite, its boundary with space is called the Kármán line.

These are the layers of the atmosphere

Depending on the temperature, The atmosphere can be divided into troposphere, stratosphere, mesosphere, thermosphere and exosphere with transitional layers between them. tropopause, stratopause, mesopause and thermopause.


It extends from the surface to about 15 km at the equator and 8 km at the poles. The temperature decreases with height to -50°Cit contains 75% of the total mass of gases that make up the atmosphere and meteorological phenomena occur.


From 15 km altitude to 50 km. In this case, the temperature increases with height up to 18°C due to the presence of stratospheric ozone.

layers of atmosphere
Layers of the atmosphere.


Above it is the mesosphere, it extends to 80 km the temperature decreases with height to -80 °C.


The temperature rises again on arrival temperatures of 1500ºC due to the absorption of high energy radiation and extends up to 600 km.

outer sphere

After this and from 600 to 800 km begins the outer layer or exosphere, which it contains only 1% of the total mass of the atmosphere. Its gases are in atomic state and can expand up to 1200 km.

What is a Kármán line?

Although the Kármán line, the boundary between the atmosphere and spacehas caused much controversy over the years about its location, most scientists point to it at the lower limit of the thermosphere, at an altitude of 100 km. But if the atmosphere reaches a height of 1,200 kmhow can the Kármán line be the boundary with space if it is 100 km away?

Let’s start by defining the space, don’t panic. The space is considered as the place where the boundary between aeronautical flight (airplanes) and astronautic flight (satellites) lies.

karman line
Kármán Line, where the atmosphere is too rarefied for aeronautics.

An aeronautical flight can continue to travel as long as its airfoil and the surrounding air can lift. This does not happen at high altitudes. because the higher an aircraft flies, the less dense the surrounding air will be and the less lift it will have. To correct it, the pilot would have to increase speed, otherwise gravity would push him down.

The speed the airplane must reach to maintain itself at high altitudes is called orbital velocityand coincides with the speed required to keep a satellite in orbit. This elevation is called the Kármán line.

Is it really 100 kilometers?

According to Theodore von Kármán, yes. This aeronautical engineer suggested that the most reasonable edge of space would be near where orbital forces exceeded aerodynamics.

Years later, the International Aeronautical Federation agreed with him. But many scientists appreciate it the border of the blue planet would be 20 km below, in the mesosphere, at an altitude of 80 km above the earth’s surface.

Today there is still no unanimous definition, but what is clear is that the Kármán line will be increasingly available to everyone: Unless you tell Jeff Bezos, the billionaire that it only took him 11 minutes to leave Earth, get to it and come back.

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