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Ancient Egyptian Astronomy. Some Historical Background. What Constituted Ancient Egypt. Timeline. 7500 BC: Earliest permanent settlements. 3100 BC: Early Dynastic, Egypt unified 2700-2150 BC: Old Kingdom 200-1750 BC: Middle Kingdom 1550-1050 BC: New Kingdom
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Timeline • 7500 BC: Earliest permanent settlements. • 3100 BC: Early Dynastic, Egypt unified • 2700-2150 BC: Old Kingdom • 200-1750 BC: Middle Kingdom • 1550-1050 BC: New Kingdom • 1050-332 BC: 3rd Intermediate/Late Period • 332-30 BC: Ptolemaic Period • 30 BC: Roman Conquest
Early Dynastic Period • Egypt grew out of a loose collection of farming villages, each with various traditions. • Villages formed alliances, creating kingdoms. • Egypt was finally unified around 3100 B.C. • The Early Dynastic Period was a time of internal consolidation. Other than for trading, there were no international aspirations. • Even in this early period, the features of pharonic were established. • The first stone buildings were constructed.
Old Kingdom • The pyramid age. • Pharaohs considered divine. • Centralization of power in the pharaoh. • Concrete evidence of Egyptian presence beyond the Nile Valley in Lebanon and Sinai. • Huge advances in the fields of building, technology, writing, and art. • First funerary texts, which mention the stars. • Ended with a gradual decentralization of power that led to complete anarchy.
Middle Kingdom • Emerged with the recentralization of power in the pharaoh, originally a local ruler from Thebes. • Never reached the heights of the Old Kingdom. • Pyramids were still built, although now with mud brick faced with stone. • With internal stability, Egypt expands South into Nubia (Sudan) for trading goods, especially gold. However, Nubia is not annexed and remains more of a colony. • Eventually, Northern Egypt is invaded by the Hyksos, who established themselves in the delta region at Avaris. Egyptians retained the South and were based in Thebes.
New Kingdom • A reunified Egypt builds an true empire and annexes many conquered peoples. • No more pyramids, building now concentrates on temples and tombs in the Valley of the Kings. • Most of these gains are lost under the religious reformer/heretic pharaoh Akhenaten. • Successors to Akhenaten regain what was lost. Egypt peaks in influence under Ramesses the Great. • After Ramesses’ death, Egypt goes into a slow decline, with high priests eventually rivaling the pharaoh in power. Egypt splits internally, greatly weakening the country.
Later Egypt • Egypt is no longer the dominant power in the region. • Characterized by brief resurgences and periods of foreign domination. • Last native pharaoh, Nectanebo II flees into exile in 343 BC after losing a major battle to the Persians. • Alexander the Great conquers Egypt in 332 BC. Descendants of his general, Ptolemy, establish a line of Greek pharaohs, who increasingly come under the influence of Rome. • With the Roman conquest in 30 BC, Egypt ceases to be a sovereign nation.
Nilometers • Egyptians were farmers. • To anticipate the Nile, which flooded annually, Egyptians needed a calendar. • Measuring flood depth was helpful for anticipating the growing season. • With just the right amount of water, the flood would deposit a thick layer of nutrient- rich Nile mud.
Telling Time of Day • 24 hour days. Sundials during daylight • For night, divided the path along the ecliptic into 36 groups of stars called decans, which rise about 40 minutes apart. • Called decans because first helical risings of each decan are about 10 days apart. • The Egyptian hours were lengthened/shortened so that day/night would always be 12 hours. • This was done for religious reasons so that rituals could be done by the hour.
The Egyptian Calendar • 365 day year. • New year started with the first helical rising of Sirius, more importance of Sirius later. • 10 day weeks, 36 weeks in a year. • 12 lunar months of 30 days. • 5 extra days to make lunar and solar calendars align. • 3 seasons: Inundation: Jul.-Oct. (Nile flooded), Sowing : Nov.-Feb (planting crops), Dry: Mar.-Jun. (harvesting). • It is believed that the monuments were built during inundation, when the fields were flooded.
Calendar Problems • The approximate ¼ day left over was discounted. • No leap years. • After every four years, the calendar would be about a day off. • In 100 years, the calendar would be about 25 days off. A complete cycle was 1460 years. • This 1460 year cycle was called a “Sothic Cycle,” after Sirius, “Sothis” in Greek. • In time, the calendar alone was useless for predicting the Nile’s movements.
Not to Fear… • Sirius, visually the brightest star, could also be used to predict the Nile. • Shortly after the helical rising of Sirius, just ahead of the Sun, the Nile flooded. Because of precession, this is no longer accurate. • As a result, Sirius became important, eventually becoming associated with the goddess Isis, goddess of among other things, rebirth. This becomes important later. • The Nile flood leads to rebirth of the land.
The Dog Days of Summer • We have the Egyptians to thank for this phrase. • Every summer, Sirius becomes invisible when it moves into the glare of the Sun. • Thinking the bright Dog Star lent it’s heat to the sun, the Egyptians coined the term “Dog Days of Summer” to describe the hottest period of the year.
Pyramids • Tombs started off simple and became increasingly complex, culminating in the pyramids. • The earliest pyramids were stepped, creating a staircase to heaven. • The Step Pyramid is 200 feet tall and almost 5000 years old. It also has 3 ½ miles of tunnels underneath.
The Giza Pyramids • Oldest and only surviving member of the 7 Wonders of the Ancient World. • The Great Pyramid is almost 500 feet tall, has a base of 13 acres, contains about 2.3 million blocks weighing an average of 2.5 tons each. • More interesting are the architectural features, which may have astronomical significance. • The other pyramids are “only” 450 and 215 feet tall.
More Mythology • The Southern facing “air shafts” point to Sirius, associated with Isis and to Orion, associated with the god of death/rebirth, Osiris. • The Northern shafts point to circumpolar stars Alpha Draco and Kochab, more on this later. • The circumpolar stars were called “The Immortals” because they never set. • Sirius and Orion equate to rebirth.
More Pyramid Astronomy • All pyramids are orientated to the four cardinal directions. • The Great Pyramid is closest, being less than 1/20th of a degree (3 arc minutes) off of true North. • Perhaps done by looking at the Immortals. • There was no North Star, the Celestial Pole was a point directly between Mizar and Kochab. • When these stars were vertical of each other, true North was indicated.
Later Pyramids • Stars remained important to a lesser degree. • Ancient texts still mention the king’s spirit stellar journey. • However, architects would not take the trouble to construct shafts pointing at the stars after the Great Pyramid. • Quality of construction declined.
The pyramid on the right is actually about 1000 years newer.
The Valley of the Kings • By this time, the sun was the central symbol of rebirth. • Although less important than before, stars were still depicted in tombs. • Astronomical ceilings often depicted constellations and the hours of the day as seen by Egyptians.
Obelisks, Stone Sun Pillars? • Tall pillars carved from a single stone, often capped with Gold and dedicated to the sun god, Ra. • Coincidently, as Ra rose in importance, stellar associations lessened. • This transition started taking place shortly after completion of the Great Pyramid
Celestial Alignment • Built by Ramesses II, known as “The Great,” this temple not only has statues 70 feet tall in the front, but extends almost 200 feet into the mountain. • Despite its vast size, the temple is aligned so that on the 20th of October and February, the sun shines into the inner sanctuary. • According to legend, one of these dates is Ramesses’ birth or coronation day.
An Astronomical Achievement • At a cost of $80 million at the time, the two temples at Abu Simbel were dismantled from 1964-8, moved up 200 and back 600 feet to escape the rising Nile, caused by construction of the Aswan High Dam.
At A Glance • Like many other ancient societies, the Egyptians first became interested in astronomy for practical purposes. • As civilization progressed, people began to attach deeper meanings to objects in the night sky. • More than anything else, architecture embodies the astronomical knowledge of Ancient Egypt.
When reading about Ancient Egypt, especially works of a speculative nature, be on the lookout for… Warning:
Getting Serious • There is a lot of outlandish, recklessly speculative material on Ancient Egypt. • Often, authors take a quite reasonable theory or genuine unknown and transform it into something completely unrecognizable. • These books make a good read, but shouldn’t be taken too seriously. • Speculative authors often completely ignore any evidence that contradicts their theories.
Pyramids have been… • Encoded ancient mathematics. • Repositories for lost, ancient knowledge. • The Biblical grain storehouses of Joseph. • Prophecies in stone. • Built by survivors from Atlantis. • Built by aliens. • Power plants. • Weapons of mass destruction (not kidding!)
