Name of satellite Luna (Moon)
Planet of origin Earth
Discovered by Known since ancient times
Date of discovery Known since ancient times
Surface color White gray
Mass 7.348 x 10^22 kg
Apogee 253,381 miles
Perigee 226,606 miles
Apoapsis 253,381 miles
Alternate name(s) Moon
Named geographical features Swift

Luna, more commonly referred to as the Moon, is the Earth's only satellite and is the fifth largest satellite in the Solar System. Yet, it is the largest natural satellite of a classical planet in the Solar System in relation to its host planet, being only one-fourth smaller than Earth.


It's unknown how the Earth's moon was created. We know that the moon was bombarded by meteorites and over time was filled with lava and violent volcanic activity as well. The Moon was later cooled by water from meteor impacts along with the Earth, thus ending the heavy late bombardment period.


Interior StructureEdit

The interior structure of the Moon is similar to the Earth. The first layer is dirt and the second layer is crust. The beginning of the internal structure is the mantle. Under the moon's upper mantle is a hollow space.

Interior StructureEdit

The Moon has an atmosphere. The Moon is covered with caverns, craters, and meteorite impacts from millions of years ago. The largest and probably most known crater is the Swift crater, caused by a meteorite impact from about five hundred million years ago.

The Moon's composition of gases inside of the regolith, or any rock harder or visibly darker than the surrounding rock, acts upon the surface, causing dark spots on the Moon to form called "maria", or non-plural, "mare". These maria are also caused by the debris that is kicked up into the atmosphere due to meteor impacts from the inner regions of the Solar System. When this debris returns to Earth, it stains the land and causes dark patches, which are the maria.

Since the Moon is heavily cratered, many of the famous craters are found here, such as the South Pole-Aitken basin, being the largest crater in the Solar System, taking up about 2240 kilometers, taking up about three-sevenths of the surface of the Moon.

Phases of the MoonEdit

The phases of the moon occur between the time period of the Moon's orbit around the Earth. Between this 27.3-day period, sunlight from the Sun will be reflected by the moon at a certain angle. This angle will only light up a portion of the Moon, and only one side of the Moon can be lit up at any one time. The side that is lit up is called the bright side while the portion not lit up is called the dark side. During its orbit, the Moon's reflection angle of sunlight will change, and due to its position, the phases will be different all around the world.


Phases of the Moon

In the photo above, the phases of the moon can be seen as it orbits the Earth. The diagram shows that the same side of the moon is always being show, yet the view from Earth differs as it changes location in space over a period of about 28 days.

  • New Moon - this is the first phase of the Moon. This phase takes place during the beginning of the Moon's orbit around the Earth. In this phase, the dark side of the Moon is facing Earth, while the bright portion is being lit up by the sunlight on the other side. No parts of Earth will be able to see the Moon.
  • Waning Crescent - the second phase of the Moon. During this phase, the dark side of the moon begins to receive some of the reflected sunlight, therefore creating a crescent-shape. Over about three days, this crescent will become larger, yet the appearance makes it look as if it is becoming smaller, which the term "waning" implies.
  • Third Quarter - this is the third phase of the moon, hence the name. During this phase, half of the dark side is illuminated, which then becomes the bright side of the moon. Half of the moon appears illuminated.
  • Waning Gibbous - this is the fourth phase of the moon. During this phase, the moon resembles a gibbous,  a shape where one side is more proportionally overtaken by the other. Again, the "waning" term refers to the gibbous seemingly to shrinking yet it is actually growing, as proven by the next phase. This phase can easily be mistaken for the other phase, waxing gibbous. The difference between the two is that a waning gibbous will always show up on the right side.
  • Full Moon - this is the fifth phase of the Moon. During this phase, both the dark and bright sides of the moon are both illuminated by sunlight. The moon appears to have a more hue-like color. It also looks slighty larger and a more detailed surface is seen.
  • Waxing Gibbous - this is the sixth phase of the Moon. During this phase, the gibbous of the Moon will appear to gradually become larger, yet it is, in actuality, shrinking. The difference between this phase and the, more commonly mistaken for, waning gibbous, is that this phase will always show up on the left side of the Moon.
  • First Quarter - this is the seventh phase of the Moon. During this phase, only half of the Moon is illuminated by sunlight, yet the sides are once again flipped, where the dark side becomes the bright side and the bright side becomes the dark side.
  • Waxing Crescent - this is the eighth, and final, phase of the Moon. During this phase, another crescent is displayed. The term "waxing" refers to the a portion seemingly becoming larger when it is actually shrinking. In this case, the Moon is actually shrinking and slowly, after about three days, becomes a New Moon, thereby starting this phase over again after 27.3 days.

Rare OccurrencesEdit

Blue MoonEdit

The term "blue moon" describes the second full moon to appear in one lunar month, which is approximately 29.5 days. The term does not describe the color of the Moon during this period, for the origin comes from a misinterpretation of a definition from the 1946 issue of Sky and Telescope.


Solar Eclipse (1)

In the photo above, an eclipse can be seen. The moon can be seen in front of an obscured Sun, only its corona being shown around the moon's circular disk.

Eclipses are rare occurrences when which either the Earth, Sun, and Moon (or vice versa) are interlocked in a straight line, called a "syzygy". There are two types of eclipses: a solar eclipse and a lunar eclipse. A solar eclipse occurs when the Moon is between the Earth and the Sun. A solar eclipse can only appear during a new moon. On the contrary, A lunar eclipse is when the Earth is between the Moon and the Sun. Unlike the solar eclipse, lunar eclipses only appear during a full moon.

Eclipses are, in solar terms, difficult to "create". The diameter of the Sun is four hundred times that of the Moon, yet the Moon is four hundred times further away from the Sun than the diameter of the Sun, therefore making it appear that the Moon is just as large as the Sun. The Moon has to align in such a way as to make this appear this way, therefore creating the "difficulty".

Varieties of EclipsesEdit

Annular eclipses are eclipses caused when the Sun and Moon are in an exact line, yet the size of the Moon is apparently smaller than that of the Sun. This causes the Sun to become a bright disk called the annulus.

A total eclipse occurs when the Moon completely blocks out the Sun's annulus, therefore blocking out, not only the Sun, but the Moon itself. Therefore, even on a phase, excluding a full moon, such as a waning gibbous, there will still be no visible Moon.

Hybrid eclipses are eclipses that transition between a total and an annular eclipse. On certain points upon the Earth's surface, one region might experience a total eclipse while another receives an annular eclipse. These eclipses are somewhat rare compared to other phenomenon.

A partial eclipse is an eclipse that occurs when the Sun is not completely in line, causing the Moon to only partially obscure the one, which the name "partial" eclipse implies. Partial eclipses can appear to be different eclipses at polar regions, for the umbra may not act as concentrated on the other regions, therefore creating this perspective.

Shadows of an EclipseEdit


The diagram above shows the Moon between the Earth and the Sun during a solar eclipse. The Sun's direct light can be seen hitting the moon, forming the penumbra. The shadows from this light, the umbra, can be seen, traveling to Earth to form the illusive solar eclipse.

Eclipses are a result of shadows, which causes the Moon or Sun appears to be dark during such an event. Two main shadows are involved in the illusion of an eclipse, and they are listed below.

  • Umbra - the shadow that creates the illusion of an eclipse; caused by the sunlight from the Sun striking the Moon directly; this direct light travels around the moon, and causes it to appear darkened or black.
  • Antumbra - the shadow that gives the illusion that the Sun and Moon are of equal size; the closer an observer moves, the more of the obscured object, in this case the Moon, can be seen, for more of the shadow is appearing the surface of the Moon.

However, shadows are only a result of a light source, and in this case, it is sunlight from the Sun itself. The sunlight in a solar eclipse causes the outer layer of the Sun to show around the disk of the Moon. Though the outer layer is known as the corona, during an eclipse, this outer layer of light is known ad the penumbra. The penumbra is responsible for the shadows during a solar eclipse, and appears around the Moon during such an event.

Images of EclipsesEdit

Tidal AffectsEdit

Due to the Earth rotating on its axis about twenty-eight times faster than Moon makes one orbit around Earth itself, this causes the gravitational pull of the Earth and Moon to become "dragged", therefore causing surface water of Earth to bulge. This causes the water to compact into large waves as it reaches the shore called "tides".

Many factors play a role into the height of the waves though: the friction created through the Earth and Moon's gravitational pull, the inertia, or non-movement, of the water, and the movement of the ocean surface. Therefore, the height of the tides are determined through these factors. As the movement of the surface increases, the water begins to move faster until approaching the shore, which pushes up the water, continually increasing the size.


The Moon makes one orbit around the Earth in 27.3 days. This can become lengthened to 29.5 days due to Earth's rotation around the Sun. During Earth's orbit, the Moon's reflected light will become influenced by this, causing the phases to become lengthened or shortened, resulting in a longer sidereal period, which is the period in which Moon makes one orbit.


Despite a combination of few gases, the Moon has no physical atmosphere surrounding the surface, therefore asteroids can easily impact the surface with little restriction. This is responsible for the thousands of craters upon the Moon's surface, by which asteroids continue to crash into the surface, leaving more and more. Few elements have been discovered in the atmosphere such as potassium and sodium. Yet, basic nutrients of an atmosphere, which include nitrogen, oxygen, hydrogen, and carbon, are not found in the atmosphere yet in the regolith.


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