Ancient Egyptian Astronomy

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Ancient Egyptian Astronomy
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Some Historical Background
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What Constituted Ancient Egypt
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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

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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.

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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.

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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.

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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.

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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.

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Astronomys Practical Beginnings
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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.

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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.

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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.

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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 Niles movements.

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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.

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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 its heat to
  the sun, the Egyptians coined the term Dog Days
  of Summer to describe the hottest period of the
  year.

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Astronomy in Architecture
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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.

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Giza, Last Wonder of the Ancient World
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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.

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Inside the Great Pyramid
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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.

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Orions Belt On Earth?
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Not Exactly
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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.

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Were the Pyramids Modeled on the Zodiacal Light?
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Later Pyramids

• Stars remained important to a lesser degree.
• Ancient texts still mention the kings 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.

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The pyramid on the right is actually about 1000
years newer.
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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.

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Astronomical Ceiling
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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

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Just For Scale
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Temple of Abu Simbel
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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.

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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.

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And the Alignment Survives!
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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.

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Warning

• When reading about Ancient Egypt, especially
  works of a speculative nature, be on the lookout
  for

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Bologna
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Cheesy Theories Filled With Holes
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and Loony Toons
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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 shouldnt be
  taken too seriously.
• Speculative authors often completely ignore any
  evidence that contradicts their theories.

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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!)?

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Yeah Right