First Recorded Lunar Eclipse
The first recorded lunar eclipse took place on March 19, 721 B.C., and was documented by Babylonian astronomer-scribes using cuneiform writing on clay tablets. Babylon, a leading city of ancient Mesopotamia located in modern-day Iraq, had a rich tradition of astronomical observation, driven by both religious beliefs and agricultural needs. The Babylonians meticulously tracked celestial events to interpret the will of their gods and to time crucial agricultural activities. They recognized the cyclical nature of eclipses and integrated this knowledge into their calendars, viewing the Moon as the deity Sin, associated with knowledge and divination. Lunar eclipses occur when the Moon passes into Earth's shadow, which can create different types of eclipses—penumbral, partial, or total—each with varying visibility. Unlike modern perspectives, which understand eclipses scientifically, ancient cultures often perceived them as ominous events that required ceremonial responses to maintain cosmic order. The rarity of total lunar eclipses, which can exhibit a reddish hue, further contributed to their mystical significance in ancient societies.
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First Recorded Lunar Eclipse
First Recorded Lunar Eclipse
The first lunar eclipse known to have been recorded occurred on March 19, 721 b.c., and was observed and registered by Babylonian astronomer-scribes, who kept diaries of celestial events in cuneiform writing on tablets of clay. (Stacks of these tablets have been uncovered by archaeologists.) Babylon was one of the most prominent cities of ancient Mesopotamia, which lay in what is roughly modern Iraq.
The peoples of Mesopotamia took a great interest in astronomy for both religious and agricultural reasons. Their priests watched the skies to decipher the will of the gods and to determine propitious times for religious rites and the planting and harvesting of crops. Of all the Mesopotamians, the Babylonians were the most advanced in astronomy: They realized that eclipses occured in cycles and incorporated them into their calendars. They called the moon Sin (lord of knowledge) and honored him as the god of calendars and divination; if angered he might cause leprosy. Since eclipses were often thought to portend trouble, it was important to know when they would occur so that appropriate ceremonies could be held to counteract their dangerous influence and restore cosmic order.
Eclipses are well understood by modern astronomers, who do not consider them omens of disaster. A lunar eclipse occurs when the Moon, which revolves around Earth, passes through Earth's shadow and is abruptly cut off from the light of the Sun (sunlight reflected from its surface is what makes the Moon seem to glow in the night sky; it generates no light of its own). Although the Moon orbits Earth approximately once a month, lunar eclipses do not happen on a monthly basis, for two reasons. First, the Earth's shadow, at the distance of the Moon's orbit, is not nearly as wide as the Earth itself. The shadow stretches like a long cone behind Earth (away from the Sun), narrowing to a point approximately 857,000 miles away. That cone of shadow is called the umbra, and at the distance of the Moon's orbit, which is 240,000 miles from Earth, the umbra has a diameter of only about 5,700 miles. A region of duskiness called the penumbra surrounds the cone, but this too narrows with distance. The Moon's orbit would have to be very precise to pass through the umbra and/or the penumbra on a monthly basis, and it is not—it is slightly irregular; this is the second reason why eclipses are relatively uncommon.
Lunar eclipses may be penumbral, partial, or total. Penumbral eclipses—barely noticeable, since they do not involve a distinct shadow—typically occur several times a year, as do partial eclipses, when only a portion of the Moon is in shadow. Total eclipses, when the Moon is entirely obscured by the umbra for up to two hours, are more rare, typically occurring no more than twice a year on widely separated nights, and in many years not at all. Even during a total eclipse, the Moon does not necessarily go completely dark. It can appear to glow with a reddish or coppery light, an effect caused by light rays being refracted by Earth's atmosphere (and regarded as particularly sinister by the ancients, since red is the color of blood). Whether or not an eclipse can be viewed depends on the weather and the geographic location of the observer—only those on the night side of Earth have any chance of seeing an eclipse.