The lunar month is used by different cultures around the world. In the Middle East, people mark the beginning of this month when a young crescent moon appears after a close pairing of a celestial body with the Sun occurs or maybe about one or a couple of days before. Egyptians determine the beginning of this month when the Moon is no longer visible before sunrise.

A lunar month is equivalent to a synodic month with an approximate length of 29 days, 12 hours, 44 minutes and 3 seconds. There other ways of interpreting this particular month.

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Atmosphere Of The Moon

The atmosphere of the moon is very different from the atmosphere on earth. While the earth actually has an air temperature, the moon's atmosphere is so thin that there is no air temperature. The atmosphere of the moon is considered to be surrounded by a vacuum, but there are atomic particles from the moon's surface create a “lunar atmosphere” for scientific purposes. This lunar atmosphere is comprised mostly of argon and helium. It cannot absorb measurable amounts of radiation. Sound cannot travel on the moon because of the lack of an atmosphere. There is also no “daytime” or “nighttime” because of the lack of an atmosphere. We can see the reflection of the sun off the moon's surface at night, but unlike earth, there is no atmosphere to trap sunlight.

What Does No Atmosphere Mean?

Because of the lack of atmosphere, there is no air temperature. There is no daylight, and sound cannot be transmitted. The scientific lunar atmosphere is generated by electrostatic activity of “moon dust” and other ions which may be present in space.

Because there is no real atmosphere of the moon, it is unfit for any type of habitation. That means the moon could not sustain life of any kind, whether it be plant, animal, or anything else in between. While moon missions have been proven, the moon's atmosphere is not capable of creating or sustaining life of any kind.

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Methods for Calculation

The first person to scientifically calculate the distance of the Moon from Earth is Hipparchus in 2nd century BC. He used the methods of trigonometry to calculate the distance. His measurement was about 26,000 km (16,156 mi) off the right distance. The error he made was about 6.8%. There were other mathematical calculations which were more accurate. These mathematical calculations were made with the help of reference points. This was done by choosing the fixed stars as reference points.

More accurate measurements were made by high precision instruments which can calculate the time taken by light to travel from Earth to the Moon. A laser beam is sent from the LIDAR (Light Detection and Ranging) station on Earth. This light beam is reflected back to Earth by retroreflectors placed on the surface of the Moon. With this setup it is able to calculate the distance of the Moon from Earth with a precision of millimeters.

Actual Distance of Moon from Earth

The Moon is not always at a constant distance from the Earth. At times the Moon comes closer to Earth and at times it is further away. The closest position of the Moon is called lunar perigee and the distance at that time is calculated to be 356,700 km (221,643 mi). When the Moon is away from Earth, it is called apogee. At apogee, the distance of the Moon from Earth is 406,300 km (252,463 mi). The average of these two distances gives the actual Lunar Distance, 384,400 km (238,855 mi). The time taken by light to travel this distance is 1.26 seconds. Lunar distance has some significance in astronomy. Near Earth Object Catalog of NASA gives the distance of comets and asteroids in Lunar Distances.

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The Layers of the Moon

Much like Earth, the moon is comprised of layers. There is the hard outer crust, which is rocky and dusty. Just beneath the outer crust lies an outer mantle, then an inner mantle, and at the very center is the core.

Outer Mantle

The outer mantle of the moon is comprised of another rocky layer. This rock is softer than the layer on the outer crust, but it is not hot enough to flow.

Inner Mantle

This layer of rock is actually so hot, it becomes molten. The rock in this portion of the moon flows as a liquid, and creates seismic waves which can create volcanic eruptions and what we consider earthquakes. Still, this liquid layer of rock is not nearly as hot as what lies underneath the Earth's crust, and does not generate enough heat to warm the dark side of the moon during the different lunar phases.

Core

The core of the moon is comprised of a very solid piece of rock. Again, it is much smaller than the Earth's core, and it is made up of an iron-like substance. The core of the moon creates a magnetic pull which is responsible for creating the tides of the ocean, though it is only one ten-millionth of the Earth's gravitational pull.

The moon is a fascinating body in the night sky. It is the 5th largest satellite in our solar system, and much like the earth consists of several layers of rock at varying temperatures and textures.

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History of the Moon Through Religion

The moon has been a central religious symbol since the beginning of humanity. The Ancient Egyptian Goddess Isis was symbolized by the moon. She was the most powerful of all the Ancient Egyptian dieties, more powerful even than Ra, the God of Sun. In Ancient Rome, Luna was the goddess of the moon, the hunt, and fertility. She was fabled to have driven her silvery chariot across the night sky.

The Moon and Psychosis

It has long been speculation that the moon has played a role on psychiatric disorders. The term “lunacy” comes from the Roman goddess, Luna, referring to the moon. In 1987, a book was written by psychiatrist Arnold Lieber stating that since the body is made up of mostly water, it makes sense that the moon would have the same effect on the human body as it does on the tides.

Art and the Moon

Vincent Van Gogh is perhaps one of the most notable artists of all time. Many of his paintings depict the moon, from Cypresses to Starry Night. During the Rennaissaince, Michaelangelo created a work called Creation Of Sun And Moon. Art has been an important medium in which artists have depicted the importance of the moon.

Science and the Moon

Until Galileo, the moon, the Earth, and the sun were thought of as “heavenly bodies”. Because they were “heavenly bodies”, they were supposed to be absolutely perfect spheres. When Galileo observed the moon through his telescope, he noted different hills, valleys, and craters as the sun cast shadows on different areas of the moon. He also took measurements through constant observation. In these observations, he noted that the moon was NOT perfect. It cast doubt on whether or not it was truly a “heavenly body”, and a lot of doubt about what exactly was created by God. Centuries later, the moon has been the source of space missions, and we know that the surface of the moon is very different from the surface of the Earth. The 20th century led to the first ever Space Walk, where we were not only able to gauge a more accurate composition of the moon, but measure its climate and mass as well.

The moon is kept in orbit around the Earth by the gravitational pull of our planet. It appears in our sky night after night and throughout the course of human existence has been a source of mystery. While we know more about the moon now than we ever have, the history of the moon will continue to be rich, noble, and colorful.

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The age of the Moon can be estimated by examining rocks that were brought back by the Apollo missions which landed on the Moon. Evidence that the Moon was formed by a giant collision between the Earth and another proto-planet can be found in lunar rocks which have almost the identical oxygen isotopes as those found in terrestrial rocks. This fact supports the hypothesis that portions of the Moon originally came from Earth.

The widely accepted age of the Moon is based upon radiometric analysis of lunar rocks. This technique analyzes naturally occurring radioactive isotopes in lunar samples against their decay properties. These decay properties are based on nuclear physics and are a known quantity which can be precisely measured. Of the moon rocks brought back by the Apollo missions, the oldest ones have been dated to 4.36 billion years old, suggesting that the Moon might be up to 200 million years younger than previously thought.

The fact of the matter remains, that as dating techniques are modernized and fine-tuned, many of the older theories about the Moon's formation have been reexamined and many experts simply do not agree on the exact age of the Moon. Current wisdom does agree that the Moon was once part of Earth and broke away during an ancient collision with another large planetary body. The Moon is therefore thought to be approximately the same age as the Earth, about 4.53 billion years old.

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Crust

The crust is the outermost layer of the moon and it consists of a dusty outer rock layer which is known as the regolith. The regolith is a rocky layer that looks like broken concrete which has been blasted apart and fused back together. The crust is approximately 37 miles in thickness on the side which faces the earth and approximately 62 miles on the other side. The rocks found on the crust are almost the same as those found on the crust of the earth. The only difference is the fact that the rocks have more aluminum and titanium than those found on earth. The moon's crust also contains some magnetism like the crust of the earth. Studies show that this layer mainly comprises of silicon, iron, magnesium, oxygen, calcium and aluminum.

Mantle
This is the layer between the core and the crust of the moon. The mantle is divided into two parts. The first layer of the mantle is the rigid lithosphere (upper mantle). This layer of the moon is estimated to be 620 miles in thickness, and it is not hot enough to flow.

The second layer of the mantle is the athenosphere (lower mantle). The athenosphere is not rigid like the upper mantle. The innermost parts of the athenosphere are hot enough to flow. The athenospheric layer is capable of transmitting seismic waves which cause quakes. The mantle is believed to be largely comprised of olivine, orthopyroxene and clinopyroxene minerals.

Core

This is the innermost layer of the moon which consists of rock that is very rich in iron alloyed with small amounts of nickel and sulfur. This layer is very small with a radius of about 225 miles or less. The moon's core makes only 2-4% of the total mass of the moon. This layer does not create a big magnetic field. The lunar core is believed to be partially molten. The magnetic field of the moon is estimated to be 1/10 millionth of the magnetic field of the earth.

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Interestingly, although the moon appears perfectly uniform in size from where we are, its mass is not evenly distributed. Instead, beneath several of the moon's basins, there are concentrations of mass known as Mascons. Because of the way that the moon's mass is distributed, any spacecraft set to orbit the moon is prone to problems with orbital stability.

Due to its lower mass, the moon's gravity is 1/6 that of the planet Earth. That means that those who have explored the moon (12 people in all) were not able to walk on its surface the way that people are able to on Earth. Although it looks different from the Earth–its color and lack of vegetation being the most striking differences–the moon and the Earth actually share the same composition. This has led many scientists to believe that our satellite was at one time a part of the planet itself.

Many people think that the moon is just another planetary body, but it actually serves an important purpose. Because the Earth is not perfectly round like a ball (it is more oblong in shape because part of it is flattened), it wobbles slightly on its axis. The moon helps to stabilize this wobble, which has also helped to stabilize Earth's climate. This effect on the weather is thought to have helped facilitate the formation of life on Earth. The gravitational pull of the moon also contributes to the ocean's tides.

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The Moon shining brightly in the night sky looks really big as compared to all the other stars twinkling beyond. Is this an illusion or is the Moon really big? Perceiving the Moon to be big by looking at it is not a real measure of the Moon's actual size. What we see is actually a deception. The Moon looks bigger than all the stars we see because it is much closer to the Earth. Stars are thousands of light years away and hence look smaller, even though some may be many times bigger than the Moon. How big is the Moon – the figures below give the actual measurements.

Actual Dimensions of the Moon

The Moon is spherical body with a diameter 3476 kilometers (2160 miles). It has a total volume of 2.195 × 10¹⁰ km³. The surface area of the Moon is 37,932,000 km² (14,658,000 miles², which is approximately 9.4 billion acres. The Moon has a mass of 7.347 x 10²² kg.

These figures are the actual measurements of the Moon. These however are mere numbers. How do you translate these into something that you can perceive in terms of the actual size of the Moon? Let us compare it to Earth to get an idea how these numbers translate into an object.

Size comparison between Earth and Moon

The Earth's diameter is 12,742 km (7,918 mi) which is almost 4 times that of the Moon. The Moon's volume looks like a daunting figure. But factually it is a mere 2% of the Earth's volume. The surface area of Asia alone is 44,000,000 km², which is more than the total surface area of the Moon. The Moon's mass is minisicule as compared to the mass of the Earth. It is estimated that 81 spheres the size of the Moon would be needed to match the mass of the Earth.

According to these figures and comparisons, the Moon is not very big. It is definitely smaller than the Earth around which it revolves.

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Difference in Diameters of Earth and Moon

A comparison of the diameters of the Earth and the Moon show the former has as diameter of 12,742 km (7,918 mi) and the latter has a diameter of only 3,476 km (2,160 mi).

Surface Area Contrast

Since the diameters of the Earth and Moon show such disparity, it is obvious the same would be observed in the surface areas of the two as well. The Moon's surface area is very small in contrast with that of the Earth. While the Earth's total surface area is 510,072,000 square km that of the moon is only 37,932,000 square km. The moon's surface area is just a small fraction of that of the Earth.

Comparing the Mass

The Earth's mass is also greater than the Moon's mass. The Earth is massive in size when matched up to the Moon. It would take more than 80 Moons to equal the mass of the Earth, since the Moon's mass is approximately 1% that the mass of the Earth.

Volume of Earth and Moon

With all the parameters used for measuring size pointing to the Earth being bigger, the same results are expected from the volume of the two celestial bodies. The Earth boasts of a gigantic volume that measures 1,083,210,000,000 cubic kilometers. The Moon's volume on the other hand is 21,958,000,000 cubic kilometers.

Conclusion

Simply stated, the Earth is much bigger than the Moon in all aspects. If the two are looked at from space the Earth would dwarf the Moon.

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