EGYPTIANS:
Because the Egyptian approach to astronomy is non mathematical, their
astronomy will never become predictive, as does that of the Babylonians.
The Egyptians could add, subtract, multiply, divide, and calculate simple
areas (e.g. squares, triangles, rectangles). Despite those skills, there
does not appear to have been a complex geometric knowledge.
Their astronomical focus will remain on fixed stars rather than on
planets. Many of their buildings will be oriented to fixed stars with amazing
accuracy. This can be readily understood if we realize that the egyptian
religion was based on Ra the sun god and emphasized stability and the correspondance
between the heavens and the earth. By 3000 BCE they have identified groupings
of stars(=constellations) which represent likenesses to mythological beings
or animals, along with a zodiac which marks the ecliptic, the sun's yearly
path through the 12 zodiacal constellations.
No doubt they were aware of precessional motion also although we have
no records to support that.
The egyptian astronomical tradition was much more extensive than we
know, and there are clear indications that much of it had been preserved
in the great library of Alexandria. Unfortunately, with the destruction
of the Library and the temples and their records in 391 CE under the edict
of Theodosius insured that virtually all the knowledge of the egyptians
disappeared. What we know is mainly reconstructed from archeological records
from the past two centuries.
The Egyptian Civil Calendar
Just as the path of the sun over a year is divided into 12 constellations so is the day and the night divided into 12 parts, the hours. Originally of different lengths depending on the seasons, the 12 day hours and the 12 night hours will evolve into fixed length hours of 60 minutes. During the day time is based on on the gnomon (sun dial). It is thought that some, if not most, of the obelisks were used as sun dials. At night, time is measured with first appearance of stars on the horizon and later also with water clocks.
BABYLONIANS
The Babylonians focus on numerical rather than geometric relationships
associated with a felt need for accurate prediction
2000 BCE identified the motions of planets. calculations are based
on arithmetic progressions to describe recurring phenomena
Identify the ecliptic, the sun's yearly path through 12 constellations
(the zodiac). After 1500 BCE, there are systematic mathematical tables
that note conjunctions of the moon and planets with stars, using mathematical
tables. position of the sun, moon and planets re computed for regular intervals,
so that planetary and lunar phenomena could be predicted. base 60 math
and place notation. could compute reciprocals squares, square roots, cubes
and cube roots.add subtract multiply divide mathematical theory of movements
of bodies using such variables as the velocity of the sun and monn
angles between the ecliptic and the horizon, magnitude of eclipses
By 500 BCE they have such an enormous observational data base thatcan
predict lunar eclipses and somewhat solar eclipses. They probably knew
how to do this much earlier. The predictions are based on a mathematical
(numerical rather than geometric) algorithm, based on millenia of observations.
Some evidence that they thought the earth was spherical. The celestial
sphere is an imaginary sphere that rotates from E-W
Sun, Moon 5 Planets move relative to the background of stars
Mesopotamian calendar is lunar. Because the lunar year is about 11
days shorter than the solar year, therefore they have to aqdd an extra
monthh about every 3 years. This addition is haphazard until~500 BCE when
the metonic cycle is introduced. Every 19 years, the lunar and solar calendar
come back in phase if we add 7 months during this 19 year cycle. Babylonian
month (as jewish and islamic) begins with first sighting of the new crescent
moon.
Greeks
acquire babylonian knowledge beginning 1000 BCE developed geometry
and simple trigonometry; focus was and remained on geometrical explanations
of heavenly motions rather than numerical
Acquired constellations from Babylonians have a total of 48 constellations