Moon Atmosphere & Composition| Does the Moon Have an ...

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Moon Atmosphere
The moon is the earth's only natural satellite, and it lies about 240,000 miles, or 385,000 km, away from our planet. Studies suggest that the moon is situated in the exosphere, which is the outermost layer of our planet's atmosphere. So, is there an atmosphere on the moon? If yes, then does the moon have an atmosphere like Earth? Also, is the moon present in the earth's atmosphere? Well, in the past, scientists thought that the moon had no atmosphere. However, recent studies confirmed the presence of a very thin and tenuous atmosphere on the moon. Unlike Earth's atmosphere which has several layers that decrease in density as they get farther from the earth, the moon's atmosphere consists of just one layer. In this single layer, the gases and other constituents in the moon's atmosphere are so spread out that they rarely collide with one another. This type of atmosphere with a low-density nature is often called a surface boundary exosphere. The surface boundary exosphere is the most common type of atmosphere in our solar system. The particles or molecules in the lunar (pertaining to the moon) atmosphere collide with the moon's surface. Other objects in the solar system that are known to have surface boundary exospheres include Mercury, many moons orbiting the giant planets of the solar system, larger asteroids, and some of the distant Kuiper Belt objects beyond Neptune.
Properties of the Moon's Atmosphere
View of Earth and its moon from space
The moon is one-quarter the size of our planet and has a diameter of 2,159 miles, or 3,476 km. It weighs about 80 times less than Earth. The moon's atmosphere, which is more appropriately called an exosphere, is very thin and has a density of only 100 molecules per cubic centimeter. This air quality is something we consider to be a vacuum on Earth. Since the mass of a celestial object is directly proportional to the gravity it exerts on other objects or molecules in its atmosphere, the smaller the celestial object, the lower the gravity (or smaller the gravitational field) and the lower the escape velocity. This makes it harder for the celestial object with a relatively small mass to retain an atmosphere. The moon's small size means that it has low gravity and low escape velocity, which makes the moon unable to hold on to much of its atmosphere. The supersonic solar wind contributes to the thin atmosphere of the moon as it heats the atoms and molecules causing them to attain high velocity. The solar wind also removes molecules and atoms of gas away from the moon. As a consequence, the moon's equatorial temperatures reach a boiling 250 degrees Fahrenheit during the day as the solar wind directly bombards its surface. However, the night temperatures decline to a chilly -208 degrees Fahrenheit. Thus, the thin atmosphere often causes great variances in the moon's temperature. The lack of a substantial atmosphere also means that during the daylight hours, the sky from the moon appears black.
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Moon Atmosphere Composition
An instrument called the Lunar Atmospheric Composition Experiment (LACE) deployed on the surface of the moon during the Apollo 17 mission has given some clues about the moon's atmosphere composition. This instrument detected small amounts of a large number of atoms and molecules. Moon's atmosphere is largely made of helium, neon, argon, and hydrogen. Helium, neon, and argon are chemically inert gases that do not react with other elements under normal circumstances. However, hydrogen is highly reactive. The lunar atmosphere is also composed of small amounts of various molecules such as ammonia, methane, potassium, sodium, and carbon dioxide.
Is there Oxygen on the Moon?
Now the question arises, if the moon has an atmosphere, then is there oxygen on the moon like in the earth's atmosphere? The answer to this question is yes, there is oxygen on the moon. In fact, there is plenty of oxygen on the moon. Surprisingly, however, it is not breathable as the oxygen on the moon does not exist in its gaseous form. Rather, it is trapped inside the rocks called regolith that cover the moon's surface. These rocks, which form the top layer of the moon, are mainly composed of around 45 percent oxygen. If extracted, this would be enough oxygen to support about 8 billion people on Earth for around 100,000 years. So, is there breathable air on the moon to support life? Well, the answer is no. The absence of breathable oxygen on the moon, combined with other factors including lack of water and insufficient gravity, makes its atmosphere unsuitable for life as we know it to breathe and live.
When astronauts aboard the Apollo 11 landed on the moon, they planted a flag on its surface. But is there wind on the moon to make a flag flutter? Scientists noticed that due to the lack of a substantial atmosphere, the moon lacks wind. Thus, it is not possible for the flag that was planted on the moon to flutter.
Moon Atmosphere Pressure
The flimsy atmosphere of the moon has a pressure 300 trillion times smaller than the earth's pressure at sea level. The moon's atmosphere pressure is reported to be {eq}3\times 10^{-15} {/eq} bar, which equals {eq}2.96\times 10^{-15} {/eq} atm. It is almost negligible when compared to Earth's atmospheric pressure, that is, 1 atm.
The mere presence of mass is enough to produce a gravitational field. Thus, the moon having a mass means that it has a gravitational field that moves with it as it revolves around the earth. The gravitational field exerts an attractive force on anything having a significant mass that wanders into the field. However, the moon's gravitational field is much weaker than that of Earth. This is mainly due to the smaller mass and radius of the moon. The moon's gravitational field at its surface is only one-sixth times the Earth's field. This helps conclude that a 186-pound person on Earth would weigh only 31 pounds on the moon.
Lesson Summary
The moon is the earth's only natural satellite. It has the most common type of atmosphere called surface boundary exosphere. The lunar (pertaining to the moon) atmosphere is very thin and tenuous where the atoms and molecules rarely collide with each other. Instead, they only collide with the moon's surface. Contributing to the thin atmosphere around the moon, the solar wind removes the molecules and atoms of gas away from the moon. The thin atmosphere causes the temperature on the moon to vary greatly during the day and night. The sky from the moon is always black, including during the daylight hours.
The moon's atmosphere (with a density of only 100 molecules per cubic centimeter) is largely made of helium, neon, argon and hydrogen. Other constituents of the moon's atmosphere, including ammonia, methane, potassium, sodium, and carbon dioxide, are found in small amounts. Due to the small size of the moon, it has less gravity which makes the moon unable to hold on to much of its atmosphere. Regolith forms the top layer of rocks over the moon's surface and also traps plenty of oxygen in its non-gaseous state. Moon's atmosphere has a negligible pressure and its gravitational field is just one-sixth of Earth's gravitational field.
Is there any atmosphere on the moon?
Yes, the moon has an atmosphere. It is largely composed of helium, neon, argon, and hydrogen. Other constituents contributing to the moon's atmosphere include ammonia, methane, sodium, potassium, and carbon dioxide.
Is the moon's atmosphere breathable?
No, the moon's atmosphere is not breathable as there is no air to breathe. Moon has plenty of oxygen which, in the gaseous state, could support about 8 billion people for around 100,000 years. However, the oxygen is trapped in the top layer of rocks on the moon called regolith making the atmosphere unsuitable for breathing and living in.