Exospheres is the most outer layer of Earth’s atmosphere. It lies just above the thermosphere. It covers approximately 600 km to where it begins to thin out and merge with the interplanetary space. Read some amazing Exosphere facts here!
The exosphere is approximately 10,000 kilometers or 6,200 miles in size and about the same size than the Earth. The top edge of Earth’s exosphere is approximately half way to Moon.
For other planets that have substantial atmospheres The exosphere forms the layer that lies above the more dense atmospheric layers however, for satellites or planets with no dense atmospheres the exosphere is the space between the interplanetary and surface space.
It is also known as the boundary exosphere on the surface. It has been observed for Moon, Mercury, and the Earth’s Moon, Mercury, and the Galilean moons of Jupiter.
The term “exosphere” comes from the Ancient Greek words exo, meaning beyond or outside and sphaira, which is a synonym for sphere.
Exosphere Characteristics
The particles of the exosphere are extremely from each other. They don’t really fit the definition of “gas” because the density isn’t enough for interactions and collisions to take place. They aren’t necessarily plasma because the molecules and atoms aren’t all charged electrically. The particles in the exosphere could travel hundreds of miles along an axis of ballistic motion before colliding onto other particles.
The Earth’s Exosphere
The lower border of the exosphere, at which it joins the thermosphere is known as the thermopause. The elevation above sea level is 250-500 km, up at 1000km (310 up to 620 miles) according to the solar activity. The thermopause is also known as the exobase, exopause also known as the critical altitude. Above the point, barometric conditions are not applicable.
Also, read 50 Fascinating Facts About Sun!
In the exosphere, temperature outer layer is close to constant and extremely cold. The uppermost boundary of the exosphere, sun’s radiation on hydrogen surpasses the gravitational pull that it exerts towards Earth.
The exobase’s fluctuation caused by solar storms is crucial because it influences atmosphere drag that affects space station as well as satellites. The particles that cross the boundary disappear from Earth’s atmosphere and sent to space.
The exosphere’s chemical composition differs from the composition of the layers below it. The lightest gases only exist, which are held only to the earth by gravity. The Earth’s exosphere is composed predominantly composed of hydrogen, Helium carbon dioxide and the atomic oxygen. The exosphere can be seen from space as a blurred area called the geocorona.
The Lunar Atmosphere
On Earth there are approximately 10019 molecules for every cubic centimeter sea air. On the other hand it is less than one million (106) molecules in the same amount within the outer atmosphere. The Moon doesn’t have an actual atmosphere as the particles aren’t circulated and don’t absorb a lot of radiation, and must be replenished.
However, it’s not an atmosphere, neither. Moon’s surface boundary is an average pressure of 3-10 atm (0.3 nano Pascals). The pressure is different based on the time of night or daytime, however the total volume weighs around 10 tonnes. The exosphere is formed through the outgassing of radon as well as Helium from radioactive decay.
Micrometeor bombardment, the solar wind bombardment, and solar wind also produce particles. The unusual gases that are found in the moon’s exosphere however, not in the atmosphere that of Earth, Venus, or Mars comprise potassium and sodium.
Other compounds and elements found in the Moon’s Exosphere include neon, helium-4, argon-40 oxygen, methane, carbon monoxide, nitrogen as well as carbon dioxide. The trace amount of hydrogen can be found. Small amounts of water vapor might be present.
In addition to the exosphere in addition to its exosphere Moon may also possess an “atmosphere” of dust that hangs over the surface because of electrostatic levitation.
Fun Exosphere Fact
While the exosphere of Moon is a near vacuum it is larger than the exosphere of Mercury. One reason for this can be that Mercury is more close to the Sun and therefore the solar winds can remove particles faster.
- The exosphere is located at 311 to 621 miles away from the earth’s surface. It closes at around 6200 miles from surface of the earth.
- While the exosphere is not the longest layer of the earth’s atmosphere, it’s the layer that acts as the first line of defense against sun’s radiation. The exosphere is the very first one that comes into contact with earth and shield it from asteroids, meteors and cosmic radiation.
- The temperature of the outer atmosphere is variable and ranges from 0 to 1800 degrees Celsius. It’s colder in the night, but much warmer during the daytime.
- The exosphere’s air is extremely thin and is composed mainly of hydrogen and helium. Other gases, like atomic oxygen as well as carbon dioxide are also discovered.
- The topmost level of the exosphere the furthest location from Earth that is not affected by gravity on earth. But this distance is about halfway to the moon and can only be considered to be accurate in an technical sense. Due to this, the actual limit of the exosphere is debated among scientists.
- If the boundaries of the exosphere are believed to be the point at which it is still influenced by the gravity of the earth, then the exosphere will be the biggest part of the earth’s atmosphere. If the boundaries of the exosphere are thought to be around 6200 miles away from surface of the earth, as many consider that it is, then the thermosphere constitutes the biggest portion of earth’s atmosphere.
- The term “geocorona” is used for the part of the exosphere that is visible from Earth.
- The exosphere is ideal for satellites because there is minimal friction, and they are able to orbit without being disturbed.
- The majority of the molecules in the exosphere eventually get returned to the lower levels of the atmosphere due to gravity. Certain molecules do go to space, however due to the lower gravity and the pressure of the exosphere.
- The tension in the exosphere is caused by solar winds that are able to compress it.
- The exosphere extends to the dark blue/black region that extends beyond the earth. Meanwhile, mysospheres are dark blue and further away from the surface are the cloudy regions of the troposphere and stratosphere.
- Since the air is very thin inside the exosphere,, the molecules don’t collide as they do in the lower layer of atmosphere. The majority of molecules are able to return to higher layers in the air, but certain ones zoom out into space instead.
