By Robert Trout
It is, today, a commonly believed myth that before the time of Columbus, everyone thought that the earth was flat, and located in the center of the universe, with the rest of the universe orbiting around it. In fact, over 2000 years ago, Greek scientists, using only the most simple instruments, developed an advanced conception of the universe that could have explained the ordering of the solar system, and how this ordering determined the seasonal cycles on the earth. They had even discovered the precession of the equinoxes to begin comprehending the longer astronomical cycles. Today, we will examine Greek discoveries in astronomy through Heraclides of Pontus, who refuted the world view of the baby boomer generation, more than 2000 years before the first boomer was born.
Greek astronomy was based on a scientific method which was in opposition to the methods used in ancient Babylon. The astronomy of the ancient Babylonians is an excellent example of how an oligarchical society does not develop science. The Babylonian oligarchy used a pantheon of cults to control the population. The priest caste studied the heavens for the purposes of omen astrology and for the improvement of their calendar, which was a lunar one unlike the superior Egyptian solar calendar.
The Babylonians left behind thousands of cuneiform tablets pertaining to astronomy. However, in the Babylonian approach to astronomy, not even a trace of a geometrical model is visible. Instead, they developed numerical methods using arithmetic progressions, in a fashion that would remind one of Euler. Using these methods, they were able to predict certain phenomena with the moon, within an accuracy of a few minutes. Although they compiled almost complete lists of eclipses going all the way back to 747 B.C., the Babylonians collected almost no reliable data on the motion of the planets. They never developed accurate methods for measuring the location of celestial objects, and never showed any interest in developing a unified conception of the cosmos.
Greek science developed as part of a cultural current which rejected the domination of an oligarchy. In the Homeric epics, man was presented matching his wits against the oligarchical Greek goods. In Aeschylus’s play, “Prometheus Bound,” the character, Prometheus, the Greek word for forethought, gives science to mankind, to free them from the pagan gods.
Greek culture, was, itself, split between a pro-republican and an oligarchical view, which is brought into sharpest relief by the opposing outlooks of Plato and Aristotle. Plato supplied the scientific method which has guided science ever since. He launched a research project to find “what are the uniform and ordered movements by the assumption of which the apparent movements of the planets can be accounted for.”
Around 150 A.D., under the Roman Empire, the fraudulent astronomy of Ptolemy was imposed, which was based on the ideology of Aristotle. The writings of the Greeks, with few exceptions, were not preserved, so the only records that exist are usually descriptions by later commentators. Therefore, we must reconstruct these discoveries, based on knowing how the mind functions.
Unlike the Babylonians, the ancient Greek astronomers sought a geometrical ordering principle behind the phenomena which are visible in the heavens. An early Greek astronomer would have seen that the motion of the objects in the sky appeared to follow regular cycles. As well, the cycles of the sun, moon, stars, and planets did not exactly correspond, giving rise to longer subsuming cycles.
Each day he would see the sun appear to rise in the east, cross the sky, and set in the west. The moon also rose in the east, crossed the sky and set. However, the moon seemed to travel slower than the sun, with the sun going through a complete extra rotation in approximately 29 1/2 days. The appearance of the moon also changed, going through a complete cycle of phases approximately every 29 1/2 days.
At night, he would see stars, most of which appeared to maintain a fixed relationship to each other. The Greeks developed a conception of a celestial sphere to explain the fixed relationships of these stars. The “fixed stars” rotated as a group throughout the night, around a point in the northern sky which appeared to not move. Also, the position of the “fixed stars” appeared to shift slightly, from day to day, with the same east to west rotation. This slight shift, from day to day, in the fixed stars appeared to go through a complete cycle each year, corresponding to the cycle of the seasons. A number of other cycles corresponded to the year. The sun’s path across the sky changed each day following a yearly cycle.
In addition to the “fixed stars” of the celestial sphere there were a few objects, which they named planets or wanderers, because, although they appeared very similar to stars, they did not remain in the same position in relation to the celestial sphere, but were constantly moving with respect to the rest of the stars.
One of the first known Greek astronomers, Thales, (ca 624 to 547 B.C.) is reported to have measured the angular size of sun and moon at approximately 1/2 degree. Thales, developed basic relations of similar triangles, such as demonstrating that the ratio of 2 sides is the same for similar triangles, and used this principle to measure relations in the cosmos.
Pythagoras (ca 572-? B.C.) is credited with discovering that the earth is approximately a sphere, and that the “morning star” and the “evening star” were the same, what we, today, call the planet Venus. He is also credited with discovering that the musical intervals are determined by number, and recognizing that the universe was governed by the same laws of harmony as those which govern music.
Since no writings from Pythagoras or his followers have survived, we can only speculate how he discovered that the earth is spherical. He might have concluded this based on conceptualizing the cause of eclipses. The discovery of the cause of eclipses is attributed to Anaxagoras (500-428 B.C.), who hypothesized that the sun was a red hot stone and the moon made of earth, for which he was accused of impiety. He recognized that the source of the moon’s light is the reflection of sunlight. He is credited with discovering that an eclipse of the moon is caused by the earth blocking the sun’s light from shining on the moon, and that an eclipse of the sun is caused by the moon blocking the sun’s light from reaching the earth.
Eclipses of the moon give evidence that the earth is spherical. The shadow that the earth makes on the moon during an eclipse is always circular, regardless of the direction from which the sun is shining. This is only true of a sphere, in the geometry that the Greeks were then developing.
Pythagoras could have discovered that the earth is spherical, because he conceptualized the idea of curvature that Erathosthenes understood, which enabled him to design his famous experiment to measure the circumference of the earth. Finally, Pythagoras could have concluded that this must be true, because he recognized that the universe is ordered by geometry and he thought that “the sphere is the most beautiful of solid figures.”
The “morning star” and the “evening star” are the two brightest objects in the night sky after the moon. The two phenomena each go through visible regular cycles, which Pythagoras was able to see were reflections of a subsuming cycle which ordered the two visible cycles.
The “evening star” first appears slightly above the western horizon shortly, after the sun sets. Over a period of months, it will appear each evening, when the sun sets, in a slightly higher position above the western horizon, travelling westward each night apparently in tandem with the rotation of the celestial sphere. Eventually it will appear, when the sun sets, at a position approximately 1/2 of a right angle above the western horizon. It will then start to appear, each night, at a slightly lower position above the western horizon, until it does not appear at all in the evening sky. However, shortly thereafter, the morning star becomes visible.
The “morning star” will first appear, on the eastern horizon immediately before the sun rises. Each night, it will rise slightly earlier, and travel westward apparently in tandem with the rotation of the celestial sphere. Its height above the eastern horizon, when the sun rises, will increase each night, reaching a maximum of slightly more than 1/2 of a right angle. It will then begin rising, later each night until, it rises so late that its appearance is hidden by the daylight. However, shortly after the morning star disappears, the “evening star” will then reappear on the western horizon.
Conceptualize how Pythagoras could have approached this problem, without all the knowledge of the solar system that you think that you know. For Pythagoras to have hypothesized that these two stars were the same, required that he approach the universe with the understanding that it was ordered, lawfully, and its lawfulness was comprehensible by human reason. Only then could he discover that the appearances of the two visible phenomena could be lawfully explained as the result of a process which could be comprehended by the mind but not seen by the senses. His hypothesis could have been that the morning and evening stars were the visible evidence of an object, which accompanied the sun in the sun’s apparent daily rotation around the earth, while oscillating back and forth over a period of approximately 20 months, half the time preceding the sun and half the time following it.
Pythagoras’s discovery, that these two visible phenomena in the night sky were the same, may seem trivial. However, his discovery set the stage for Heraclides of Pontus, approximately 200 years later, to overthrow the baby boomer conception of the universe, as we shall see below.
Philolaus, (second half of 5th century B.C.), a member of the Pythagorean school, introduced conceptions of motion to an earth, which had previously been thought of as largely static. Philolaus is credited with removing the earth from the center of the universe, and replacing it with a central fire, around which the rest of the universe, including the earth, rotated. This hypothesis was gradually rejected, because the existence of a central fire was never verified.
Plato (ca 427-347 B.C.) developed the scientific method, which was inherent in the work of the Greek scientists who preceded him, and was mastered by all scientists who followed him. In the Republic, Plato described how, when the senses give the mind contrary perceptions, the mind is forced to conceptualize an idea which is intelligible rather than visible. Astronomy compels the soul to look upward, not in a physical sense, but towards the realm of ideas. The study of astronomy required that man discover the true motions of the heavens, rather than merely their motion, as it appeared. “These sparks that paint the sky, since they are decorations on a visible surface, we must regard, to be sure, as the fairest and most exact of material things, but we must recognize that they fall far short of the truth, the movements, namely, of real speed and real slowness in true number and in all true figures both in relation to one another and as vehicles of the things they carry and contain. These can be apprehended only by reason and thought, but not by sight, or do you think otherwise?” Further on Plato adds, “It is by means of problems, then, said I, as in the study of geometry, that we will pursue astronomy too, and we will let be the things in the heavens, if we are to have a part in the true science of astronomy and so convert to right use from uselessness that natural indwelling intelligence of the soul.”
Plato rejected the world view of the oligarchy, who projected their own evil caprice onto God, and asserted that the universe was “controlled by a power that is irrational and blind and by mere chance.” On the contrary, Plato stated that he followed “our predecessors in saying that it (the universe) is governed by reason and a wondrous regulating intelligence.” The creator made a universe which is ordered harmonically, by mind that produces order and arranges each individual thing in the way that achieves what is best for each and what is the universal good. Therefore, man can comprehend the universe through reason.
Plutarch wrote of Plato ” … that Plato in his later years regretted that he had given the earth the middle place in the universe which was not appropriate.” Plato laid out a research project for his students to find “what are the uniform and ordered movements by the assumption of which the apparent movements of the planets can be accounted for.”
Heraclides of Pontus, (ca 388-315 B.C.) was a student of Plato at the Academy in Athens. Born more than 2000 years before the advent of today’s baby boomer culture, he made a crucial discovery which all too few baby boomers today have replicated. He discovered that the entire universe was not rotating around the earth, (and around him, who was standing on it) as would appear to be the case to one who believes in sense certainty. Rather, the cause of the rest of the universe appearing to revolve around the earth was that the earth is, itself, rotating around its axis. He also discovered that the cause of the apparently erratic motion of Venus and Mercury is that they are revolving around the sun. While Heraclides still believed that the Sun revolved around the Earth, his discovery that Venus and Mercury revolved around the Sun, set the stage for the later discovery that the Earth and all the other planets also revolved around the Sun.
Although he wrote numerous dialogues including two discussing astronomy, only a few remarks by commentators have survived the dark age, initiated by the Roman Empire, on how he made this remarkable discovery. We must reconstruct how he could have done it. What he must have done is conceptualize an idea of the nature of the Universe, and comprehend that his idea was more real than sense certainty.
The commentator Aetius reports that Heraclides thought that each of the innumerable stars in the sky was also a world surrounded by an atmosphere and an aether. Others, at the time, thought that the stars were attached to some sort of dome or rings. For example, Aristotle argued that the stars and sun were objects carried on rings around the earth at such a high rate of speed that the friction between the stars and the air caused the sun and stars to give off heat and light.
Obviously, Heraclides could not have arrived at his hypothesis based on his senses. (Even in the last few years, when astronomers have developed experiments to try to determine if other stars have planets orbiting them, they have still not “seen” any planets. Instead, they are designing experiments to measure certain phenomena, such as the distribution of heavy elements in the vicinity of distant stars, and, then, interpreting the results of their experiments as proving their hypothesis.) Heraclides must have thought, “If all the innumerable stars are each a world like our own, and they are at so immense a distance, that these worlds appear only as small specks of light in the night sky; why should all of them, and the immense universe in which they are located, orbit around the one world where he happened to be located?” Instead, he recognized that the impression which he received from his senses, that the heavens were rotating around the earth, could be explained by conceptualizing that the earth was, instead, rotating on an axis.
One significant anomaly that lead Heraclides to the discovery that Mercury and Venus revolved around the sun, was that the brightness of the planet Venus and the rate of it’s change in location, from night to night, varies dramatically throughout its cycle. It takes Venus, during the “evening star” part of its cycle, approximately 7 months to rise to its highest position above the western horizon, and only about 2 months for its descent. At the beginning of this cycle, it is dim. It becomes progressively brighter, until near the end of its cycle, it is, by far, the brightest object in the night sky, besides the moon. During the “morning star” part of the cycle, Venus rises rapidly to its highest position above eastern horizon in about 2 months, and, then, decreases in position each night very gradually, taking about 7 months until it disappears entirely under the western horizon. During the “morning star” part of its cycle, Venus starts out very bright and becomes progressively dimmer.
Heraclides hypothesized that his observations were a reflection of how an object rotating around the sun, would appear to an observer located on the earth, which is revolving on its axis. This is more easily understood from the following diagram: Draw a circle with a radius of 3 inches, to represent the orbit of Venus. The center of this circle represents the sun. Then draw a point to represent the earth, approximately 4 1/8 inches from the center of the circle. (For purposes of the diagram, make this dot below the circle.) Heraclides also placed the planet, Mercury, rotating around the sun in a much smaller circle. The cycle of Mercury appears similar to that of Venus, to an observer on earth. However, Mercury is usually much fainter than Venus, and reaches a maximum altitude in the sky only around 1/3 that of Venus.
In the diagram, the motion of Venus, would be represented counterclockwise around the circle. (Remember that Kepler’s discovery of elliptical orbits is almost 2000 years later.) The earth is rotating, daily, on its axis (counterclockwise in our diagram). The clearly visible differences in Venus’s brightness are explained by the dramatic differences in its distance from the earth at different places in its orbit.
Draw 2 lines from the earth, that are tangent to the orbit of Venus. At the points of tangency with the circle, the angle between Venus and the sun is greatest, and Venus will appear the highest in the night sky to an observer on earth. Draw a line through the sun and the earth which bisects the orbit of Venus.
Now, conceptualize what an observer standing on the earth, which is rotating counterclockwise, will see. In left half of the orbit, Venus appears as the “evening star,” and in the right half it appears as the “morning star.” Venus travels a far longer distance in rising to its highest position in the evening sky than in descending, making its assent take a far longer time than its descent. The opposite is true for Venus’s appearance in the morning sky.
Heraclides of Pontus’s discovery advanced Plato’s research project of discovering “what are the uniform and ordered movements by the assumption of which the apparent movements of the planets can be accounted for.” He set the stage for Aristarchus of Samos’s “Copernican Revolution,” which located the sun at the center of the solar system, less than 100 years later. Heraclides of Pontus, by rejecting sense certainty which leads to the baby boomers’ illusion that the Universe revolves around them, and locating his identity in agape, or the passion for discovering the truth in Platonic ideas, secured a place for himself in the simultaneity of Temporal Eternity.