Archaeoastronomy
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Archaeoastronomy can be defined as the study of the
astronomical practices, mythologies, religions and world-views
of all ancient cultures. Archaeoastronomy, in essence, is the
"anthropology of astronomy", to distinguish it from the "history of
astronomy". Vast majority of the great monuments and
ceremonial constructions of early civilizations were astronomically
aligned. The accurate cardinal orientation of the Great Pyramid at
Giza in Egypt or the Venus alignment of the magnificent Maya Palace
of the Governor at Uxmal in Yucatan are outstanding examples.
Astronomical knowledge of the ancient builders can be divided
into three areas:
- cosmology, dealing with the physical shape of the world
and the Universe,
- cyclic phenomena, things with a repetitive nature
detectable by observation alone, and
- non-cyclic phenomena, generally rare events known to be
significant to many cultures.
| Cosmology |
Cyclic
Phenomena |
Non-cyclic
Phenomena |
| Celestial sphere |
Equinoxes and
solstices |
Comets |
| Celestial equator |
Lunar eclipses |
Fireballs (bolides) |
| Celestial pole |
Solar eclipses |
Meteorite impacts |
| Pole star |
Motion of inferior
planets |
Meteor storms |
| Ecliptic |
Motion of superior
planets |
Supernovae |
| Pole of the ecliptic |
Heliacal risings and
settings |
Auroras |
| Constellations |
Achronal risings and
settings |
|
| Cardinal directions |
Meteor showers |
|
| Spherical Earth |
Comets |
|
| |
Precession of the
pole |
|
| |
Precession of the
equinoxes |
|
| |
Length of year
(non-integral) |
|
| |
Lunar standstills |
|
It is important to realize that recognition of phenomena is
different from understanding causes. Furthermore, related phenomena
might be seen as unrelated: precession of the pole and precession of
the equinoxes might be seen as separate phenomena; the connection
between comets and meteor showers might not be made. [
http://www.cloudbait.com/archaeo/arce2004.html ].
The precise and sometimes puzzling orientation of the ancient structures can be explained by understanding that
their primary function was to serve as observation platforms for priests working
with the calendar. The stone structures were perfectly constructed for
predicting and sighting a wide variety of astronomical alignments including the
solstices and precession of the equinoxes.
The best examples are the Mesoamerican pyramids constructed as an
astronomical matrix with purpose of calibration of the most important dates in
the year.
Conceptually, the Maya already had the model of the sun's behavior on which to
predicate their observations. Its northernmost stopping point marked the summer
solstice, which in turn established the beginning date for the 52-day count
which fixed "the day the world began" -- i.e., August 13. If they could locate a
similar position for the moon -- its northernmost setting point -- perhaps that
would allow them to begin the count which would eventually reveal the secrets of
the eclipse cycle.
Pinning down the movement of the sun, irregular as it was with respect to the
Long Count, was like child's play for the Maya compared to their struggle to
understand the movements of the moon. Once again their failure to recognize the
concept of fractions obliged them to undertake lengthy counts of cycles in the
hope of eventually finding two periods which coincided in nice, whole integers.
A case in point is the length of a lunation, the period of time between two
successive new moons. The Maya obviously realized that it was not 29 days, but
it also was not 30 days. Attempting to describe a time period which was actually
29 days, 12 hours, 44 minutes, and 2.8 seconds in length was for them a
philosophical impossibility. Yet, after they had counted 149 "moons" in a row
they realized that exactly 12 tuns and 4 uinals had elapsed, or a total of 4400
days; they were then confident that the cycle would begin over again, with the
moon occupying the same position it had had relative to the sun when the cycle
began. That they could do so with reasonable assurance is demonstrated by the
fact that 4400 days divided by 149 lunations yields an average of 29.5302 days
per lunation -- a value less than 0.0004 at variance with that used by modern
astronomers!
CELESTIAL AND MATHEMATICAL PRECISION
IN ANCIENT ARCHITECTURE
by MELISSA HIEBERT
Many ancient ruins demonstrate that the people who constructed
them had not only a special regard for celestial bodies and
mathematics, but also a spot-on accuracy. From Egypt to Mexico,
there is no doubt that past civilizations were involved in
incredibly complex space calculations, mathematics and architectural
endeavours. Although many historians and archaeologists debate
exactly what these civilizations did intentionally and what they did
by mere chance, here are a few examples of how ancient architecture
was created with mathematics and the cosmos in mind.
In Giza there are many examples of attention to spatial
coordinates. For instance, the Great Pyramid’s faces are aligned
with the four cardinal directions almost perfectly. In fact, they
are less than 0.2 of a degree off. The pyramid is very precise, with
the corners as little as two seconds of a degree (with 60 seconds in
a minute of a degree, and 60 minutes in a degree) off of a 90-degree
angle. In addition to this (although contested), the pyramids at
Giza seem to match the stars of Orion’s belt with a certain
precision.
The Site of Teotihuacan, “The Pyramid of the Sun,” as it has been
dubbed, demonstrates advanced math. The pyramid’s base has a
perimeter of 2932.8 feet, while the pyramid has a height of about
233.5 feet. If we take the ratio of base to height, we get about
12.56, or rather, 4p. Although to some this is thought to be a
coincidence, the pyramid’s actual ratio is less than 0.05 per cent
off of the true value for 4p.
The ancient Mayan site of Chichen Itza exemplifies the culture’s
celestial orientation. The huge step pyramid (the pyramid of
Kukulcan) that is the focus of the site has 91 steps on each of its
sides, which add up to 364 steps. Adding the platform on top, there
are 365 steps in total — the number of days in a year. Also, on the
vernal and autumnal equinoxes (the first day of spring and fall,
when day and night are the same length of time), the sunlight works
to create a shadow of a giant serpent on the staircase that faces
north.
A building called the Caracol, believed to have served as an
observatory, is also found at the site of Chichen Itza. The windows
are set up to align with certain points of interest. Although the
top is damaged, remaining windows point to the northern- and
southern-most positions of Venus, the position of sunset on the
Equinoxes, and the corners of the building itself point to the
sunrises and sets of the solstices.
The Mayans had a sophisticated calendar, losing only one day in
6000 years. Their predictions of solar and lunar eclipses were
incredibly accurate. As many have heard, they predicted a date that
they believed would be the end of the world. This date, translated
to our calendar, is on December 23, 2012. Although unlikely, the
world is predicted to suddenly end in about seven years (if we have
just translated the meaning of their calendar correctly).
The Mayans did have some rationale behind this number. This date
marks the time in the precessional cycle of the earth that we will
move out of the constellation of Pisces and on to the age of
Aquarius.
What is global precession? I’m glad you asked. Everyone knows
that the earth spins on its axis while it revolves around the sun.
Most remember from grade 10 science class that the earth’s axis is
not perfectly vertical, but rather tilted about 23.5 degrees.
However, the axis is not always this way, as it slowly varies from
about 24.5 degrees to 22.1 degrees, making a complete cycle every
41,000 years.
While it is moving in this way, due to varying gravitational
forces, the axis wobbles (precesses) in a clockwise circle. Just
imagine the way the axis of a top spins as it begins to fall. So,
the angle of the earth stays the same (or somewhere within its three
degree variance), but the direction in which it points changes. For
example, our current North Star is Polaris (or Ursae Minoris), as
the North Pole points towards this star. However, approximately
13,000 years ago, the North Pole would have pointed towards the star
Vega, as it will do again in about another 13,000 years. It takes
about 25,776 years to complete one precessional cycle.
Anyone ever heard of the song “Age of Aquarius”? Well, this is in
reference to the earth’s precessional cycle. Presently we are in the
age of Pisces, which means that when the sun rises on the vernal
equinox it rises in the direction that the constellation of Pisces
is in the sky. However, due to precession, every 2160 years on the
vernal equinox the sun rises in a different constellation. As
mentioned above, we will be moving out of the age of Pisces and into
the age of Aquarius around the end of 2012.
So, the Mayans figured there was something important to the
changing of ages, hence their predicted death date. However, they
are not the only ones who seem to have taken certain numbers into
account. The perimeter of the Great Pyramid at Giza is approximately
3,023 feet and the height is 481 feet. In addition to exemplifying a
ratio of exactly 2p, its measurements are said to possibly represent
the Northern Hemisphere of the earth, on a scale of 1 : 43,200.
Though controversial, some interpret this number as exactly 20 times
the precessional number of 2160, representing the precession of the
earth through 20 different zodiac constellations or ‘ages.’
These examples of precessional numbers, mathematics and celestial
orientations found in ancient structures by no means scratch the
surface of all of the occurrences (or at least, proposed
occurrences) present at various historical sites, and even in
cultural songs and myths. Whether or not various theories or
speculations concerning these spectacular constructions are true or
not (and we may never know), the meticulous precision that was put
into planning, calculating and building them is hard to ignore, not
to mention awe-inspiring.
And we think we’re advanced...
Source:
CELESTIAL AND MATHEMATICAL PRECISION IN ANCIENT ARCHITECTURE
Astronomical
Alignments of
Ancient Structures - MAIN PAGE
Mesoamerican Archaeoastronomy
Using the summer solstice to calibrate the secular calendar
By about 1000 B.C., knowledge of the calendars and the principle of solsticial
orientation had spread into the Olmec metropolitan area and priests had come up
with a formula for recording when the zenithal sun was passing overhead at Izapa!
In reality, the formula was as simple as it was ingenious. The
problem at San Lorenzo had been that the priests had no way of
knowing when it was August 13, because in their part of the world
the zenithal passage of the sun did not occur on that date. Thus,
they had settled on using one of the solstices instead, because the
date of the sun's turning point was the same everywhere, they had
discovered. Whereas at San Lorenzo they were obliged to use the
winter solstice sunset to calibrate their calendar, when La Venta
was founded it appears that they could once more think in terms of
the summer solstice, as had originally been done in Izapa. Indeed,
the only difference was that instead of marking the sunrise as they
did at Izapa, they were obliged to use the sunset at La Venta.
Once back in the mental groove of using the summer solstice to
calibrate the secular calendar, it would not have been long before
some priest realized that the beginning date of the sacred almanac
can itself be calibrated by reference to the summer solstice. In
effect, he was recognizing that, if the solstice occurred on June 22
and the "beginning of time" occurred on August 13, there was a fixed
interval of time between these two dates. Using our modern calendar
to demonstrate his thought process, we would count 8 days to
complete the month of June, add 31 more for the month of July, and
then count 13 until the sunset of August 13, yielding a total of 52
days. (For anyone used to thinking in "bundles" of 20's and 13's,
what a neat package this was -- 4 rounds of 13 days = 52 days.)
Thus, no matter where one wanted to build a ceremonial center, one
could always find out when it was August 13. All that was required
was to count 52 days from the time that the sun turns around in the
north and mark the horizon at sunset!
With the discovery of the Long Count with its "grand cycle" of 5125 years, Olmecs had a means of defining every day that passed as being absolutely unique.
And the position of every day within that round of 13 baktuns, or 1,872,000
days, was numbered consecutively from "the beginning."
The imprecision of the Short Count, or defining a day within a given
52-year period, was gone. Human life spans lost their meaning when compared to
the "life spans" of the sun, moon, and stars, and of the celestial rhythms which
governed their movements. (Learn more about
The Long Count-
Astronomical Precision ).
Aztec
Calendar, one of the most accurate calendars ever invented,
on display at the Museo Nacional de Antropologia in Mexico City, Mexico
Although both the 260-day sacred almanac and the 365-day secular calendar
predated the Maya by well over a millennium, and the "principle" of using key
calendar dates to define urban locations and the Long Count itself had likewise
been developed by the Olmecs several centuries before the Maya emerged as a
civilized society, it was the latter who seized upon these intellectual tools
and honed them to the highest level of sophistication of any of the native
peoples of Mesoamerica.
In the flat and featureless landscape of Yucatán, it had been a rather simple
matter to lay out a new city oriented to the sunset on "the day the world began"
because the "summer solstice + 52 days" formula had already been developed.
Astronomical
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Egyptian Archaeoastronomy
The astronomical ceiling from Senenmut's tomb
Below, the astronomical ceiling from Chamber A, TT353; it is the oldest
astronomical presentation known - the next one was found in the tomb of Sethi I.
- and naturally, it is the only one in a private tomb (from Dorman, 1991).
The astronomical ceiling from Chamber A,
Tomb TT353, the second tomb built by Senenmut.
This image leaves no doubt that ancient Egyptians
had great knowledge of astronomy.
[
Image Source ]
The ceiling is divided into two sections representing the
northern and the southern skies. The southern - upper part shown in
the picture above - is decorated with a list of decanal stars, as
well as constellations of the southern sky belonging to it like
Orion and Sothis (Sopdet). Furthermore, the planets Jupiter, Saturn,
Mercury and Venus are shown and associated deities who are traveling
in small boats over the sky. Thus, the southern ceiling marks the
hours of the night.
The northern - lower part - shows constellations of the northern
sky with the large bear in the center. The other constellations
could not be identified. On the right and left of it there are 8 or
4 circles shown and below them several deities each carrying a sun
disk towards the center of the picture. The inscriptions associated
with the circles mark the original monthly celebrations in the lunar
calendar, whereas the deities mark the original days of the lunar
month (after Meyer, 1982).
The astronomical ceiling is divided along its east-west axis by a
text band composed of five registers. The central line which is
wider than the other four registers bears together the titles of
Hatshepsut and some titles as well as the name of Senenmut. The text
reads from the right to the left :
"Live, Horus powerful of k#s, Two- Ladies flourishing of years,
Horus-of-Gold divine of appearnances, king of Upper and Lower Egypt,
Maat-ka-Ra, beloved of Amun-Ra, living; the sealbearer of the king
of Lower Egypt (sD#wtj-bitj), the steward of Amun (jmj-r# pr n Jmn)
Senenmut, engendered of Ramose (Ro-ms), justified, born of Hatnefret
("#t-nfrt)."
Dendera's Zodiac
The Egyptian Temple of Dendera, dedicated to the goddess Hathor,
is thought to have been constructed by the Ptolemies in the first
century BC, but on the site of an earlier temple. It contains two
zodiacs: a rectangular zodiac, carved in the ceiling of the
hypostyle hall, and a circular zodiac, about 8 feet across, found on
the ceiling of a chapel on the temple roof.
The zodiacs have been the subject of great controversy and have
been interpreted in many different ways. They were probably intended
to record more than one important date.
Archeologists consider the 'Circular Zodiac' to have been crafted
c 30 BC, and hence it is an Egyptian representation of the Greek
astrological view.
Original Dendera's Zodiac (photo above) is placed in museum in
Louvre, Paris. Copy of this zodiac is in Dendera.
A version, colored by an unknown artist
of the drawing of the 'circular zodiac' from an unknown source.
A version, colored by an unknown artist
of the drawing of the 'circular zodiac' from an unknown source.
Click to enlarge.
Read more (external link)>>
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Two angular coordinates are used to specify geographic position:
- latitude, an angle in
the plane containing poles and place; and
- longitude, an angle in the plane
parallel to the equatorial plane and containing the place (Stebbing, 1956:2-4.)
The altitude of the visible celestial pole above the
horizon (measured in degrees) is equal to the absolute value of the geographical
latitude.
If you observe the sky from the Earth's northern
hemisphere, the North Celestial Pole is located northwards, and the
stars (apparently) rotate about it counter-clockwise. If you are on
the southern hemisphere, you can see the South Celestial Pole in
southern direction, and the stars (apparently) rotate about it
clockwise.
If you were to stand at the North or South Pole,
the visible celestial pole would appear directly overhed to you. If
you were at the equator, however, the two celestial poles would
appear to be on the horizon.
The line on the surface of the earth through the place and both poles is
called the meridian of the place: it is a half-circle since the earth is
spherical. The angle subtended at the earth's centre by the arc of the meridian
between the place and equator is the latitude of the place. It is measured in
degrees, minutes and seconds from 0 degrees at the equator to 90 degrees north
or south at the respective poles. The angle between the plane of the meridian of
the place and the plane of a prime or reference meridian is the longitude. It is
measured in degrees, minutes and seconds, and runs from 0 degrees at prime to
180 degrees east or west according to the direction taken from prime (Williams,
1992:11). Thus 180 degrees east and 180 degrees west coincide; this meridian is
co-planar with prime (0 degrees) and is the International Date Line along most
of its length. Latitude is conventionally quoted first in giving position, but
north/south and east/west label them unequivocally. (Some nautical tables etc
may speak of latitude as a distance, but the coordinates actually refer to
angles as above. Two places a degree apart in latitude are 70 miles apart
north-south wherever they are on the globe between equator and pole; but for
single degree differences in longitude the distance apart varies (maximum at the
equator to zero at the pole).
Thus latitude alone defines all the points where a plane parallel to the
equatorial plane meets the surface of the earth. Longitude along defines all the
points along a meridian. Both are needed to specify a single point (Stebbing,
1956:1-7).
The problem for all navigators is that the sun and stars can be used to
calculate the latitude north or south of the equator but not the easterly or
westerly position that is, the longitude (Berthon and Robinson, 1991:117).
The Ease of Determining Latitude
The means to calculate latitude were mastered during ancient times. For
example, Pytheas (c.300BC) was able to calculate the latitude of his home town
Marseilles to an accuracy of approximately a quarter of a degree (Williams,
1992:9).
Sailors have long been able to determine latitude fairly easily and with
comparative accuracy (Williams, 1992:9). In the northern hemisphere the Pole
Star is in line with the earth’s axis, that is, it is always north at every
point and latitude can then be calculated by the observation of this star. Other
bodies had to be observed un the southern hemisphere when European mariners
crossed the equator.
The Difficulty of Determining Longitude
In contrast to latitude, the means of accurately calculating longitude at sea
was long elusive. Not until 1714 was there an accurate way of determing
longitude even on land, let along at sea where waves made accurate measurements
difficult. The best that sailors could do was to calculate their displacement
east-west by using a process of intelligent guess work called "dead-reckoning."
Given that this ‘reckoning’ had to be adjusted for the effects of wind and sea
in carrying a ship off-course and that these effects (called leeway and drift
respectively) could not be accurately and reliably measured it was, as Quill
(1966:2) observes, "a most hazardous way of navigating."
As the earth rotates, each meridian passes directly beneath the sun, which
has maximum altitude at noon each day along the whole of that meridian. Noon is
thus earliest at 180 degrees east and latest at 180 degrees west, these
meridians being considered, for this purpose, to be not quite coincident. There
is in fact 24 hours difference: the earth takes 24 hours to rotate, that is,
describe 360 degrees, so it covers 1 degree in 4 minutes, 15 degrees in each
hour and 360 degrees in 24 hours (Quill, 1966:4). Thus degrees of the angle,
that is longitude, can be rendered as periods of time, the difference between
local and prime time (the time at the reference or zero meridian).
Clocks at prime and the unknown place can be used to measure longitude.
Observed noon at the place serves as one clock and the other, an actual clock
carried on board, gives the simultaneous time at prime provided it has kept
accurate time since being set. Time difference in hours/24 x 360 = longitude in
degrees.
This simple conversion was to solve the problem of determining longitude, but
it called for accurate timepieces, so it was only theoretically possible for
centuries.
Measuring Lunar Positions and Distances
During the seventeenth and eighteenth centuries it was realised that if the
changes in the position of the earth’s moon could be observed and then compared
to the lunar tables prepared in Paris or London, then, theoretically, longitude
could be calculated. However, science during this time was simply not
sufficiently rigorous to be able to achieve the necessary accuracy required for
the calculations. Newton himself observed that the "accuracy of the lunar tables
was between two and three degrees of longitude - no better than dead reckoning."
(Berthon and Robinson, 1991:120).
After 1767 sailors began seeking to calculate longitude at sea by measuring
the distances of particular stars from the moon, that is, the lunar distance
method. The greater accuracy that was required to achieve this led to the
development of the sextant for use at sea after about 1770. The name of the
sextant refers to the actual arc but not to the angle that can be measured. More
accurate than the octant, sextants were produced in great numbers during the
1800s onwards. Navigators with the more wealthy companies such as the East India
Company typically used a sextant (Turner, 1980: 34).
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