If an observer peers at the moon, they may be lucky enough to catch a glimpse of something special. There are exclusive events that occur when the Earth, moon, and sun align in a straight line (Figure 1). These phenomena are collectively known as called eclipses. Eclipses are when an observer can see the light of one celestial object become obscured from another celestial object passing by. Obscuring is the concealing or darkening of an object.
There are 2 types of eclipses that can occur which are a solar eclipse and a lunar eclipse. During a solar eclipse, the moon passes in front of the sun temporarily blocking the light. During a lunar eclipse, the moon becomes darkened from it moving through Earth's shadow. The position of Earth is directly between the moon and the sun which results in the lunar eclipse (Figure 1). Lunar eclipses can only occur when the moon is in the full moon stage and are safe to observe with the human eye. On average, 3 lunar eclipses can be observed from Earth each year.
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When the moon darkens during a lunar eclipse, there are two parts to Earth's shadow that are involved. They are known as the umbra and penumbra. The umbra shadow is from the complete blockage of light creating a total darkest shadow on the moon. This often results in the moon having an orange or copper red appearance to it. The penumbra shadow is from partial blockage of light which creates a partial shadow on the moon. Both types of shadows are important as they are involved with the seven stages of lunar eclipses as the moon moves into and out of them (Figure 2).
The first stage occurs when the moon crosses into Earth's penumbra. Second, after crossing into the penumbra, the moon crosses into the umbra which begins a partial lunar eclipse. In stage three, the moon becomes completely wrapped up in the umbra shadow which starts the total eclipse. The moon continues to move through the umbra until it reaches the middle of the eclipse in stage four. This is when the center of the moon and the center of Earth are lineups meaning the moon is fully obscured. Totality occurs in this stage where the moon is fully inside Earth's shadow. It can last for almost two hours.
Stage five occurs when the total lunar eclipse ends. During this stage, the moon moves back out into the umbra. In stage six, the moon leaves the umbra completely which signifies the end of a partial lunar eclipse. In stage seven, the moon leaves the penumbra signifying the end of the eclipse (Figure 2).
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There are different types of eclipses that can occur as it all depends on the angle of when the moon crosses into Earth's shadows: penumbral lunar eclipse, a partial lunar eclipse, a total lunar eclipse, and a central lunar eclipse. Each type deserves a spotlight.
Penumbral lunar eclipses occur when the moon travels only through the penumbral shadow. This casts only a partial shadow on a portion of the moon, giving only a slightly faded appearance. Penumbral lunar eclipses are difficult to see as they occur ever so slightly. This is different from umbras which are shadows created by total blockage of light.
Partial lunar eclipses are easier to observe with the human eye. Partial lunar eclipses are when part of the moon moves through Earth's umbra. This is different from the penumbral as a portion of the moon becomes covered in Earth's shadow (Figure 3). This event occurs when the moon is full.
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Total lunar eclipses can also be viewed with the human eye and are often advertised in the news in advance. During total lunar eclipses, the moon is in between the sun and Earth which stops the sun from lighting up the moon. During total lunar eclipses, the moon is complete in Earth's umbra. All of these aspects result in an appearance that can be surprising to the viewer.
During total lunar eclipses, the moon is sometimes called a blood moon from the coppery red appearance to it. It can also appear to be a hue of browns and other warm colors from the sun's rays not refracting on the moon (Figure 4).
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Another special type of eclipse that can occur during full moons are known as the central lunar eclipse. Central lunar eclipses occur when the center of the moon crosses over the center of the umbra shadow. Central lunar eclipses are rare as they are the longest possible pathway the moon can take crossing into and out of Earth's shadows.
Lunar eclipses have been documented in history by many civilizations, including the Incas, Mesopotamians, and Chinese. The Incas were an ancient civilization in South America that worshipped Inti, the sun god. The Incas believed that lunar eclipses were irregular events caused by a jaguar attacking the moon and that the jaguar would eventually attack them. They believed that solar eclipses were caused by the disapproval and anger of Inti. The Incas fasted and practiced human sacrifices after a solar eclipse in an effort to appease the sun god.
The Mesopotamians also believed that lunar eclipses were caused by the moon being under attack. However, they believed that seven demons were after the moon, which they also viewed as an attack on their king. During the eclipses, a substitute king was crowned to face the demon. The substitute king was thought to become a sacrifice, as he then disappeared. After the lunar eclipse ended, the original king was said to return to power.
The ancient Chinese believed that lunar eclipses revealed the future for their emperors. The ancient Chinese were frightened by the disappearance of the sun in a solar eclipse and the moon during lunar eclipses. They believed a dragon attacked and devoured the celestial bodies. In order to chase the dragon or other celestial creatures away, they often made loud noises and banged on drums until the moon or sun returned.
Lunar eclipses can be observed during a full moon phase when the moon, sun, and Earth are aligned (Figure 1). Lunar eclipses are predictable due to the moon's cyclic nature, and there are many sources on the internet to determine when the next lunar eclipse will occur.
When the alignment occurs, those that are experiencing nighttime on Earth can observe the eclipse. Lunar eclipses can be viewed with the human eye as they are safe to watch, unlike solar eclipses. Total eclipses and partial eclipses can be viewed (Figure 2 & 3), while penumbral lunar eclipses are more difficult to see. Magnifying objects like a telescope can aid in watching the phenomena as they enlarge the view of the lunar eclipse.
Eclipses are when an observer can see the light of one celestial object become obscured from another celestial object passing by. There are 2 types of eclipses that can occur which are a solar eclipse and a lunar eclipse. During a solar eclipse, the moon passes in front of the sun temporarily blocking the light. During a lunar eclipse, the moon becomes darkened as it passes through Earth's shadow. Lunar eclipses only occur during full moons as they have been observed by ancient Inca, Mesopotamian, and Chinese civilizations. There are two parts to Earth's shadow that are involved known as the umbra and penumbra.
Earth's umbra shadow is caused by the complete blockage of light which creates the darkest total shadow on the moon. Totality is the period of time that the moon spends complexly inside the umbra. This results in an orange or cooper red appearance on the moon. On the other hand, the penumbra shadow is when part of the light is blocked creating a partially shaded shadow on the moon. There are four different types of lunar eclipse that can occur which are the total lunar eclipse, the partial lunar eclipse, the penumbral lunar eclipse, and the central lunar eclipse. The total and partial lunar eclipse can often be observed with the human eye as the penumbral and central lunar eclipses are more rare or difficult to see.
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The 4 types of lunar eclipses are the total lunar eclipse, the partial lunar eclipse, the penumbral lunar eclipse, and the central lunar eclipse. The total and partial lunar eclipse can be viewed with the human eye as the penumbral and central are more rare or difficult to observe.
The average of lunar eclipses that occurs in a year is 3. This includes total, partial, and penumbral lunar eclipses.
A lunar eclipse is when a full moon becomes darkened from it moving through Earth's shadow. The position of Earth is directly between the moon and the sun which results in the lunar eclipse.
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