Phases of the Moon Essay

The moon goes around the Earth roughly once every month, and it is the Moon's orbital motion that leads to different phases of the moon and eclipses. The relative positions of the Sun, Moon, and Earth at a given time determines the faction of the moon that is illuminated by the Sun. Also, the relative angle of the Moon, Earth, and Sun determines the proportion of the Moon's surface that gets illuminated. There is always a possibility of an eclipse when the moon is in front of or behind the Earth. This paper discusses the various phases of the moon, as well as the different type of eclipses.

Moon Phases

            A given proportion of the Moon’s surface is always lit or illuminated by sunlight. The amount of that light that can be visible from the Earth varies every day, creating different shapes of the moon, referred to as moon phases (Broome, 2018). The moon does not produce its own light. Instead, the moon's surface reflects rays from the sun. Moon phases are categorized into four primary phase and four intermediate phases. The primary phases of the moon occur at specific periods, while the intermediate moon phases occur at any time between the primary phases (Broome, 2018).

New Moon

            This is the first primary phase, which occurs when the Moon and the Sun are aligned, with the Moon on the opposite side of both the Sun and the Earth. A New Moon is usually not visible from the Earth because only the Moon’s dark side faces the Earth during the New Moon phase (Gudipati, 2009).

Figure 1: Position of the Moon in Space during the New Moon Phase

Waxing Crescent Moon

            This is the first intermediate phase, which begins when a thin sliver of the moon becomes visible immediately after New Moon. The Waxing Crescent Moon lasts until fifty percent of the Moon's surface gets illuminated or lit at First Quarter Moon. 0.1% to 49.9% of the Moon's surface gets illuminated during this phase (Broome, 2018).

Figure 2: Waxing Crescent Moon

First Quarter Moon

            First Quarter Moon is the second primary moon phase, which occurs when the Moon reaches or completes the first quarter of its orbit around the Earth. First Quarter Moon is sometimes called Half Moon since exactly 50 percent of the Moon’s surface gets illuminated during (Broome, 2018).

                Figure 3: Position of the Moon in Space                               Figure 4: First Quarter Moon

Waxing Gibbous Moon

            This is the second intermediate phase, which lasts until the subsequent or next primary phase. The term “Waxing” implies that the moon is getting bigger, while Gibbous relates to the formed shape, which is larger than the Moon’s shape at First Quarter, but smaller than a full Moon. The Moon is usually 50.1% to 99.9% Illuminated during Waxing Gibbous Moon phase (Gudipati, 2009).

Figure 5: Waxing Gibbous Moon

Full Moon

            Full moon often occurs when the Moon and the Sun are aligned on opposite sides of the Earth. The alignment technically lasts for a few moments, and 100% of the Moon’s surface gets illuminated or lit up (Broome, 2018).

                           Figure 6: Moon’s Position in Space                               Figure 7: Full Moon

Winning Gibbous Moon

            This is the next intermediate moon, which occurs when the illuminated portion of the moon decreases. The Winning Gibbous Moon phase occurs after the Full Moon and lasts until fifty percent of the Moon's surface gets illuminated or lit at the Third Quarter Moon phase (Gudipati, 2009).

Figure 8: Winning Gibbous Moon

Third Quarter Moon

            This is the last primary phase, which occurs when half of the Moon’s surface gets illuminated or lit (Broome, 2018).

                          Figure 6: Moon’s Position in Space                                  Figure 7: Full Moon

Winning Crescent Moon

            This is the last intermediate Moon phase, which occurs when the sun lights or illuminates less than half of the visible fraction of the Moon. The Winning Crescent Moon phase begins immediately after the Third Quarter Moon phase and lasts until the next New Moon (Broome, 2018).

Figure 9: Winning Crescent Moon

Eclipses

            Eclipses are astronomical events that occur when a given celestial body totally or partially covers another celestial body. The two primary eclipses include solar eclipse and lunar eclipse. A solar eclipse takes place when the New Moon is between the Sun and the Earth, whereas the lunar eclipse occurs when the Earth casts its shadow on the Full Moon (Foss, 2017).

Solar Eclipses

            Solar eclipses only occur or happens during the New Moon phase, when the Moon moves between the Sun and the Earth and the three celestial bodies are aligned or form a straight line. There are three forms or types of solar eclipses, which include total, partial, and annular solar eclipses (Foss, 2018).

            Total solar eclipse. This occurs when the New Moon moves between the Earth and the Sun and casts the umbra (the darkest part of Moon’s shadow) on the Earth. A total solar eclipse is almost as dark as night (Foss, 2018).

Figure 10: Total Solar Eclipse

            Partial solar eclipse. A partial solar eclipse occurs when the Moon comes between the Earth and the Sun, but only covers the Sun’s disc partially (Guy & Young, 2010).

Figure 11: Partial Solar Eclipse

            Annular solar eclipse. An annular solar eclipse occurs or takes place when the Moon appears or becomes smaller than the Sun as it moves centrally across the solar disk. A bright ring of sunlight (annulus) is usually visible during the annular solar eclipse (Guy & Young, 2010).

Figure 12: Annular Solar Eclipse

Lunar Eclipses

            The moon does not produce or generate its own light and it usually shines because its surface reflects the rays from the Sun. A lunar eclipse happens when the Earth comes between the Moon and the Sun and blocks the rays from the Sun from reaching the Moon. A lunar eclipse only occurs during the Full Moon phase. There are three types or kinds of lunar eclipses, which include total, partial, and penumbral lunar eclipses (Foss, 2017).

            Total lunar eclipse. This occurs when the Earth comes between the Moon and the Sun and the Earth’s umbra conceals or obscures the entire Moon’s surface (Foss, 2017).

Figure 13: Total Lunar Eclipse

            Partial lunar eclipse. This can be observed when only a fraction of the Moon’s surface is blocked or obscured by the Earth’s umbra. In other words, the partial lunar eclipse occurs when the Earth moves between the Full Moon and the Sun, but they are accurately aligned (Guy & Young, 2010).

Figure 14: Partial Lunar Eclipse

            Penumbral lunar eclipse. This takes place when the Moon moves through the faint penumbral section or the outer portion of the Earth's shadow. Penumbral lunar eclipse is usually mistaken for or confused with a normal Full Moon (Guy & Young, 2010).

Figure 15: penumbral lunar eclipse

Conclusion

            In overall, there are eight major phases of the moon, which are divided into four primary phases and four intermediate phases. The primary Moon phases include New Moon, First Quarter Moon, Full Moon, and Third Quarter Moon, while the intermediate Moon phases include Waxing Crescent Moon, Waxing Gibbous Moon, Winning Gibbous Moon, and Winning Crescent Moon. The major eclipses include solar eclipse and lunar eclipse. The various types of solar eclipse include total, partial, and annular solar eclipses, while the different types of lunar eclipse include total, partial, and penumbral lunar eclipses.

References

Broome, K. (2018). The 8 Moon Phases In Order. Science Trends. doi: 10.31988/scitrends.15141

Foss, K. (2017). Total Solar Eclipse Vs. Lunar Eclipse 2017: Your Guide To Be An Eclipse Expert. Science Trends. doi: 10.31988/scitrends.1950

Gudipati, M. (2009). Editorial for Earth, Moon, and Planets. Earth, Moon, and Planets, 105(1), 1-2. doi: 10.1007/s11038-009-9332-9

Guy, M., & Young, T. (2010). Creating Eclipses: Using Scale Models to Explore How Eclipses Happen. Science Activities: Classroom Projects and Curriculum Ideas, 47(3), 75-82. doi: 10.1080/00368121003697448