Since prehistoric times -- long before the time of writing -- the stars
have been used to mark off "seasons and days and
years", and the earliest historical records
imply that the major constellations had already been long identified
and named back in the mists of antiquity, many thousands of years ago.
Until very recently, one might have assumed that no written records
records at all. That all has changed with the discovery of astronomical
sky charts in the Cave art at Lascaux Cave,
dated to 17,800 BC. The
cave art itself is the ancient writing -- the ancient method to record
information about the skies (see
with the sprinkling of stars throughout the heavens (in truth it looks
anything but random02),
looks for asterisms
or patterns. Figure 1 is a map showing a number of the
constellations recognized today.
This realization builds up over time:
• The moon repeatedly
waxes and wanes over the lunar months in a regular pattern.
• The sun follows a regular track, called the ecliptic, which can be
traced on a rotating background of fixed stars. The sun retraces this
track daily, but over the months the background appears to rotate, so
that the stars that appear at dawn and dusk change, but repeat the same
patterns every solar year.
• The duration of daylight changes over a year with the shortest day at
the winter solstice (about December 21) and the longest day at the
summer solstice (about June 21). Half-way between these are the spring
and fall equinoxes (March 21 and September 21). It would take many
years of systematic observation to realize and then determine these
times, which have the practical use of signalling the year's seasons.
• Over many years, the stars show further slow changes which occur in
some cases over thousands of years.
Pattern-finding is an automatic
response of human contemplation. The mind cannot help
it: one reason why people see patterns in gambling, the stock market
and anything else that appears—or is in fact—random. This leads
naturally to the identification and naming of the major constellations
Figure 2 shows the constellation Orion—here as an archer (one of
several depictions of the constellation). The stars that form the belt
and shoulders are quite prominent, and easily recognizable because they
are among the brightest stars in the sky.
Map of Constellations
Evidence of the Constellations. By a remarkable providence
there are literally hundreds of
(and very fragile) cave
paintings preserved in France and Spain
composing what is called the Magdalenian
culture, spanning from about
18,000 to 10,000 BP (years before the present). In my view the
of these paintings is an example of a silent voice lovingly preserved
for our benefit—see the box03.
These paintings include the earliest known true sky charts—reaching
back over 20,000 years.
The prehistoric cave art
of Western Europe is one of the most remarkable discoveries of modern
times. Its preservation over tens of thousands of years is due entirely
to God's providence. The unfortunate fact is that when the cave art is
discovered, it rapidly degrades due to changes in moisture and
atmosphere, and the
introduction of fungus and various pathogens.
The discoveries were pure happenstance. They might—except
for God's restraining hand—have been uncovered at any
time in history. If they had come to light in the many
thousands of years before the age
of science, they would have been lost, and the memory would have at
best been reduced to myth and folklore, and totally disregarded by
modern science. As it is, all of the cave art discovered in the past
150 years is degraded from its original condition at the time of
aggressive effort at preservation keeps it from further loss. See
Dan Chure, The
Tragedy of Lascaux for an account of this.
The silent speech preserved by God is the cave art itself which records
the early beginnings of astronomical observation. The Lascaux cave
includes a precise sky chart that maps several
constellations in a single chart with remarkable accuracy, and is the
earliest evidence to date
that the constellation Taurus was already "named" (by a painted image
of an aurochs, ancestor of the European bull) 15,000 years before the
earliest mention in historical writing on clay tablets from Ur (see the
Babylonian Zodiac below).
A cave painting at
cave in France (Figure 3) dated 17,300
BP appears to be the earliest known sky chart, as well as
the earliest evidence for the naming of a specific constellation
(Taurus)—named, that is, by the use of a bull image, since this is
far earlier than the invention of writing. It is one of
many images in a panorama
in the Hall of Bulls that extends around the hall on the walls and
wraps up into the ceiling
. Some have asserted that the
entire panorama depicts
constellations in the sky, but I cannot verify that: some papers that
this seem to be more speculative than scientific04. See A Sky Chart at
Lascaux Cave for further information.05.
or "Realistic"? The cave paintings at Lascaux
and other sites in France
(a more recent find is Chauvet Cave, discovered in 1994 and
dated to 30,000 BP) do
not have obvious religious significance, being mostly scenes of the
hunt, of nature and other similar subjects—despite many references
to shamaans, rites and magic by the various "scholars" who comment on
Another rich source
of early artwork is found in the Egyptian temples,
crypts and coffins. These depictions—some very realistic,
some fanciful, some whimsical—are simply that. Although Egyptian
culture was rife with gods and godlets—that doesn't mean that
the painters lack a sense of fantasy and humor. For
example, consider the sky goddess Nut and earth god Shu that appear on
many ancient Egyptian coffins and paintings (Figure 4). Did the
believe that these are literal gods literally forming sky and earth, or
are the stories and
depictions of these gods on the par with Kipling's Just-So
stories? That is how I view such artistic work as this.
Certainly the Egyptians did worship nature and had many nature gods,
but they also used considerable artistic license in depicting them.
The Egyptian Sky goddess Nut and
the Earth god Shu
depicted in many burial chambers and coffins
When the book of Job
refers to the constellations Pleiades,
Orion and the Bear (Big Dipper), he does not view them as gods. They
are constellation patterns with widely accepted and
names, selected for mnemonic association. The
astrological and religious
attributions to these
constellations are almost certainly late additions layered onto the
the year to year return of the same constellations, it is
natural to mark the ones that lay along the the sun's
path (the ecliptic) on its annual journey. The sun's
"house" is the constellation that can be seen in the direction of the
sunrise, just before dawn, and at sunset. These
constellations form the zodiac
(the word means "circle of animals"). Nobody knows precisely how this
happened in the first instance, but it does seem to be a logical and
fully reasonable process, use to mark time throughout the year. Today
we commonly think of these
constellations in terms of the mythical heroes of ancient Egyptian,
Greek and Babylonian cosmologies, but their true value is not in the
supposed influence over mankind narrated in these myths and in
astrology, but in the use in time measurement—marking the seasons.
Some scientific facts fall out
automatically—over a lifetime of
careful observation—and would have been known in pre-history:
Sun's path through the fixed star background07
same from year to year: this is
called the ecliptic.
The word literally means "line of eclipses" because lunar and solar
eclipses occur when the Sun, Moon and Earth all lie in the Earth's
orbital plane. Thus the ecliptic traces out the Earth's orbital plane
in the background of fixed stars.
In a Sidereal year, the
Sun returns to the same zodiac constellation at the
same time each year. In
particular the constellation at the
spring equinox is the same from year to year, and marks the
beginning of the planting season for spring crops. The constellation
that houses the Sun at the spring equinox usually heads the zodiac.
(3) Most stars are fixed stars. Five
stars" and the Moon move relative to the fixed stars. They do not
follow the same paths from year to year,
but they do always move within about 8° of the ecliptic.
(4) The field of stars appears to rotate about a
fixed location—defining the North and South poles.
Here "fixed" is over a human lifetime. Some more subtle
facts about the Zodiac have to wait for
records recorded over many
when detailed star maps are made and observed over many years. But
these facts are enough to make the beginnings of a starry timepiece.
The Babylonian Three
Stars Each clay tablets are the earliest surviving
the constellations and zodiac. They are
dated to around 1200 BC. It can be
from this record that these constellations go back at least a
thousand years earlier to the Sumerian Akkadian Empire period,
2270-2083 BC, the
era of Sargon
and the time of the Hebrew patriarch Abraham,
when Ur was a
center of civilization. The inference comes about because many of the
constellation names in the Babylonian list are Akkadian words. For
example, the word
"constellation" or "star" in the Babylonian text is the Akkadian
constellation names also trace back to Sumerian sources: Taurus, Leo,
Scorpio, Capricorn, Gemini, Cancer. Presumably these records were
written down, but they no longer exist. It is particularly
interesting that the head of the
list is Pleiades, the Akkadian glyph MUL.MUL,,
or "star of stars". The name and head position imply that the Pleiades
were the constellation at the Vernal equinox—nominally
March 21—the beginning of the Spring planting season. This was the case
2300 BC (see the Figure 5), and lends support to the thought that the
entire star list may have originated around that time. Since the time
of the later Bablylonian star tables, Pleiades and Orion have not been
named as Zodiac signs, having been replaced by Aries, Taurus (which
includes the Pleiades) and
The book of Job mentions three constellations: Pleiades,
Orion and the
Bear (Big dipper). The mention of the Pleiades and Orion may hint at an
date for the book—when the Pleiades were considered the head of the
zodiac, i.e. around 2000-2300 BC08
. However, given the known fact that
lists of zodiac signs tend to remain unchanged for very long periods of
time, this would be rather crude evidence for dating.
The Ecliptic showing Pleiades, Taurus and Orion
of the Equinoxes.
Some of the more subtle facts
astronomy had to wait for
records taken over many
when detailed star maps could be compared over centuries. One of these
facts is that the location of the sun at
the vernal equinox moves along the ecliptic about
one degree in 70 years, returning to its initial
position after 25,800 years. This 25,800 interval is called the Great Year or
This is about five times longer
than the entire span of recorded history, but it is long enough so that
star catalogs prepared over thousands
of years will show the change.
The movement of the
equinox through the
constellations is called
of the equinoxes" and is due to the fact that the Earth's
axis precesses (much as a spinning top's axis circles around a
central axis, only of course much slower—see the figure). The
plane of the Earth's orbit doesn't change (so the Ecliptic and the
constellations of the
Zodiac are unchanged) but the time of the equinox does change. In
the north star changes. Currently
the earth's axis is aligned quite closely with the North star Polaris,
but in ancient
times that was not the case, and a few
thousand years from now, the North star will change again. Even 500
years ago in
the days of Chrstopher
Columbus, Polaris was a degree further away from the
north pole than it is today.
The earliest estimate of the
great year was made
(190-130 BC)), based on small changes in the position
of the vernal equinox since the 600 BC Babylonian star catalog.
He estimated that it takes
about 30,000 years for the Vernal Equinox to cycle through the 12 signs
equates to 2,500 years for a Zodiac sign to move to the position of its
The modern value for this parameter is 25,771 years09a.
of Hipparchus' astronomical writings have survived, all of our
information about his
work come from Ptolemy,
who wrote some 300 years later.
the zodiac sign
of the vernal equinox, which marks the
beginning of Spring, is leaving
Pisces and entering Aquarius. Figure 11 shows the precession between
BC and 2,000 AD.
Position of the Vernal Equinox
4000 BC to 2000 AD
of the Perihelion.
In addition to precession of the
Earth's axis, there is another precession that is important over longer
timescales. This is the precession of Earth's perihelion, also called apsidal
precession. Although the earth's orbit is nearly circular, it is
not exactly so, and so the gravitational tug of the other planets cause
it to precess with a period of about 110,000 years.
The Zodiac Clock. The zodiac
clock records the net effect of these two precessions. Figure 12 shows
the clock for 2,000 AD, which is part of a zodiac clock
animation. See the web page Zodiac Clock
for further details.
Constellations of the Zodiac with the calendar for 2010 AD
The Silent Speech of Astronomy in the
Language of Mathematics
The constellations and the
zodiac do not use the formality of mathematics. But to exploit the full
value of the stars as timekeepers, it is necessary to study the heavens
with its powerful logic. Thus mathematics becomes one of the particular
languages in which the Silent Speech proclaims God's glory and
handiwork. This is the language in which Einstein
worked, leading to his famous remark, "The most
thing about the world is that it is at all comprehensible."
Greek civilization first introduced mathematical formality into the
of Astronomy. Hipparchus
(~190 BC - 120 BC) "the father of trigonometry" was the first to
develop and use constructions
from spherical trigonomy, which he used to devise an effective
measurement system to record star positions in space—similar to the
present earth-coordinate system of latitudes and longitudes, which he
in degrees and minutes of arc.
By making extensive use of earlier Babylonian star
today), Hipparchus constructed a star catalog of some 850 stars visible
night sky. That catalog is also lost, or rather it was merged by Ptolemy (c. 90 AD – c.
168 AD) into his own star catalog of 1025 stars (the Almagest). This star
compares favorably with an estimated 1,602 stars (worldwide)
that are brighter than magnitude 5 and
4,800 stars brighter than magnitude 6—the faintest stars
visible to the naked eye under good conditions.
appears to have incorporated the Hipparchus tables by adding 2°40'
to the longitude of Hipparchus—1° per century for the 260 years
between the tables, which is quite accurate, taking into account the
net effect of polar and absidal precession. This is absolute position
error, not relative position error, which is generally on the order of
one to ten arc-minutes
(Ptolemy himself considered his tables to be accurate
to 10 arc-minutes)10.
Ptolemy's outstanding contribution was to develop a
model of the Solar System which could be used to calculate planetary
positions. In his model the sun and planets followed circular orbits
centered on the earth with a system of Epicycles (Figure
13) superimposed. This was a
mathematical fit to the star catalog data and a method of
calculating past and future positions of the planets and sun. Thus
Ptolemy was the first to use mathematics to project accurately the
positions into the past and future. Predictions of solar and lunar
eclipses had been done since the Babylonian days, about 600 BC, but
Ptolemy was the first to predict solar eclipses with good accuracy.
There is no
evidence that Ptolemy actually believed his fairly complicated
mathematical model—it was a mathematical fit to his star positions11. It is
that later scholars prior to Copernicus, who had an inaccurate concept
practical mathematics may have credited the Ptolemaic system with a
reality that he didn't claim—much as many antiquarians today assume
that the Egyptians accepted the "reality" of their depictions of
System of epicycles.
Click on the image for animation12.
Copernicus (1473-1543) replaced the Ptolemaic representation of the
Solar System with one in which a rotating Earth and the planets follow
circular orbits centered on the Sun (more precisely—each planet
circled around a position centered near to but not exactly at the
position of the Sun)—see Figure 14, which is an illustration from
could not dispense entirely with epicycles—although he
used far fewer than Ptolemy.
Ideally any system—Ptolemy's or
Copernicus'—had to explain the following data:
• The positions (latitude,
longitude) of the planets over time.
data of the star catalogs
• The change in the planet's
to Kepler assumed a constant speed of the planet along its path. Hence
the need for epicycles, or orbits offset from the Sun and/or Earth.
• The change in the planet's
—This is a
of the distance to the planet and—for inner planets—the phase of
the planet relative to the Sun (analogous to the phases of the Moon).
Earth-planet-Sun distance should relate to brightness. The
phases of Venus are only visible with a telescope, but the related
changes in brightness could be observed with the naked eye.
Curiously, Copernicus still needed
epicycles in his model,
although fewer than in the Ptolemaic system. In his day the position of
the Roman Catholic Church was that the Earth was the center of the
universe. Copernicus avoided conflict with the religious authorities by
presenting his calculations as a mathematical tool that was easier to
compute than the method of Ptolemy, without (at least publicly)
asserting that his model was to be equated with reality15. As
an approximation to the planetary orbits, the Copernicus model was
(somewhat) less accurate
Ptolemy's model, which by this time, had been tweaked and tested
against astronomical observations for almost 1500 years. But
computations using the Copernican model were much easier to do, and so
his model was officially adopted by Pope Gregory XIII, as the basis for
establishing the Gregorian
Calendar, which replaced the Julian Calendar,
and is still used today16
Tycho Brahe and Johannes
(1546-1601) life mission was to make more accurate star charts (Figure
many years of observation, he constructed accurate star
catalogs with (relative) errors of 1 arc-minute or slightly less.
accurate tables showed that both Ptolemy's and Copernicus' models—even
with Copernicus' epicycles and off-sets—had systematic errors.
The worst case was the orbit of Mars.
(1571-1630) attempted to use Tycho Brahe's data to infer a more
accurate model for the solar system. Regardless of his painstaking
effort, Kepler could not avoid systematic errors of up to 3
arc-minutes—well beyond the accuracy of Brahe's tables. After years of
Kepler solved the problem by using elliptical planetary orbits with the
located at one of the foci and on which the speed of the planet varied
with distance from the Sun. He established the three laws of planetary
motion that form the foundation for modern orbital calculations, and
are known as Kepler's
laws. He published these in his treatise Astronomia Nova in 1609, just
one year before Galileo transformed astronomy with his telescopic
observations, including the discovery of the Galilean moons orbiting
About 60 years later, Isaac Newton showed that Kepler's three
laws are equivalent to his law of gravitational attraction which varies
inversely with the square of the distance between the planet and the
Sun. The remarkable thing is that Kepler did his work using only
naked-eye observations. After he came up with his (correct) model for
planetary orbits, he produced the Rudolphine star
catalog in 1627. The calculations needed to produce this table were
greatly simplified by the discovery and publication of logarithmic
tables by John
Napier in 1614, with improved tables by Henry
Briggs in the following decade.
Kepler's methodology is good for projecting planetary
the distant past and future, and is especially useful for predicting
lunar and solar eclipses. Modern
astronomy programs are based on the
Keplerian laws, with adjustments for the Earth's precession and other
small variations, and have claimed accuracies of under 10 arc-seconds
for projections several thousand years in the past or future17
Astronomy in the Age
Science. Perhaps the most
astonishing advance in Astronomy came with the
publication of Isaac
Newton's Principia, which laid the
foundations of modern
physics and wedded progress in physics with mathematics, particularly the calculus. In
one fell swoop, physical science broke the shackles of earth-bound
because Newton's physics came to be seen (along with the addition of
relativity and quantum mechanics) as applicable throughout the entire
universe, and the universe itself was seen to follow precise natural
laws, giving an unexpected new illumination to the concept of the
universe as a
precision timekeeper. The impact of these advances is further discussed
as part of the Creation Narrative.
The Silent Speech in Astronomy. There are several
instances of God's provision of Silent
Speech in this short account.
• The preservation of historical records
gracious gift that God has granted to us so that we can learn details
of the past that we have no a-priori right to expect. In some
instances—such as the cave paintings—the full implications may still
to be worked out. It is clear that we had no right to expect such
graphic details to be preserved for thousands of years, and have clear
evidence of the tenuous and vanishing nature of the record, which
requires special care to avoid complete loss. It is providential that
these records were not recovered centuries ago—there is no logical
reason, apart from God's providence, why they were not—and in that
event they would have been lost
and perhaps been erased from our conscious knowledge, or
relegated to fantastic folklore from the distant past.
• The ability to express nature in
terms that can be evaluated in closed form (using simple analytical
equations), is another gift of God.
This gets to Einstein's remark about the comprehensiblity of the
mathematician should know that very little of mathematics can be
evaluated in terms of analytical expressions. The normal
expectation would be that trajectories of planets and stars would
require solution of the notoriously difficult many-body problem. Even
Newton was puzzled by the stability of the Solar System, and
conjectured that God had to intervene to preserve that stability18.
the very recent age of powerful computers, tackling such multi-body
problems as the detailed trajectories of planets would
have been utterly impossible. Would the computer age ever have dawned
if not for the ability to make significant advances using simplified
models of reality?