Until recently, we took the fact that the moon has no atmosphere. Just as the discovery of water on the moon has changed texts in textbooks about our nearest Earth neighbor, recent studies have confirmed that the Moon really has an atmosphere that consists of several unusual gases, including sodium and potassium. We would hardly seek in the atmosphere of Earth, Mars, and Venus. Compared to the Earth's atmosphere, it's an infinite amount of air. Each cubic centimeter of air at sea level on Earth contains 10.000.000.000.000.000.000 molecules. In contrast, the Moon's atmosphere has less than 1 million molecules in the same volume. This value may seem like a large number, but in Earth conditions, something like that is already considered a very good vacuum. In fact, the density of the atmosphere on the surface of the Moon is comparable to the Earth's atmosphere density at its farthest edge - somewhere the International Space Station is circulating.

So what is the Moon atmosphere created? We already know something about her. During the Apollo 17 mission, the Lunar Atmospheric Composition Experiment (LACE) was placed on the Moon's surface. Thanks to this, a small number of atoms and molecules were found, including helium, argon, neon, ammonia, methane and carbon dioxide. Scientists on Earth also use special telescopes to analyze reflected light from the Moon's surface. As a result, we are able to detect even the presence of sodium and potassium atoms, which are additionally driven by solar wind. Yet we still have only a partial list of what really makes up the lunar atmosphere. It can be expected that there will be much more.

NASA satellites Lunar CRater Observation and Sensing Satellite (LCROSS) and Lunar Reconnaissance Orbiter (LRO) have discovered significant ice deposits in craters at the Moon Poles. Furthermore, the Chandrayaan X-ray Observatory discovered a small number of water molecules in the moon's soil. From this, it can be concluded that the Moon atmosphere can play a key role in the possible cycle of water molecules between polar and equatorial regions. The Moon can not only be humid but also more dynamic than we thought so far.

One of the key differences between the Earth's and the Moon's atmosphere is the fact that atmospheric molecules move. In the dense atmosphere of the Earth, the motion of molecules is often accompanied by their collisions. In contrast, in the Moon's atmosphere, atoms and molecules almost never collide. Their movement is influenced by the lines of force of the gravitational field, yet it is very free.

Scientists call this type of atmosphere surface boundary atmosphere. Its density is almost the same from the ground to its edge. Scientists believe that such an atmosphere will be the most common type in the solar system. In addition to our moon would surface boundary atmosphere could find Mercury, most of the asteroids, countless moons of giant planets, or even some remote Kuiper Belt beyond the boundary of Neptune's orbit. So far we have very little information on how well this hypothesis is right. It's great that we have the opportunity to explore one such atmosphere right next to us on our moon so we can better understand how everything works.

One of the Lunar Atmosphere and Dust Environment Explorer (LADEE) probes is to determine the composition and structure of a lunar lunar atmosphere and to understand how its structure varies with time, including dependence on changing external conditions. LADEE's measurement comes just in time. Many nations have shown interest in exploring the moon. Future missions could significantly affect the natural composition of the lunar atmosphere.

Free translation by article NASA: "Is There an Atmosphere on the Moon?" by Briana Daye of 12.4.2013.