The Precession of the Equinoxes
Traditionally, the vernal equinox date (March 21st) has served as a reference point for calendars, for most ancient cultures. The ancient astronomers were aware that position of the vernal equinox sun, relative to the fixed stars of the zodiac, drifts slowly backwards along the zodiac, completing an entire 360° circuit around the zodiac in about 25,800 years. This slow movement of the equinoctial point backwards along the zodiac is called the “precession of the equinoxes” or simply, precession, while the cycle duration of 25,800 years is called the “precession cycle” of the earth.
Even though the Greek astronomer Hipparchus is generally credited with the discovery of precession in c.133 BCE, Hipparchus’s value of precession was off the mark by a fair bit. His calculated value of around 1° per century translates to a precession cycle of 36,000 years. In comparison, the value of precession given in the Surya-Siddhanta, the astronomical treatise of ancient India, is 54 arc-seconds per year, which gives us a precession cycle of 24,000 years.[1] This is more accurate, and the Surya Siddhanta has existed in a written form since at least the 6th century BCE, and had been transmitted through oral traditions for many thousands of years prior to that.
The philosophers of ancient India referred to the precession cycle of the earth by another name – the Yuga Cycle. In the late 19th century, an Indian yogi named Sri Yukteswar Giri wrote a book called The Holy Science (1894), in which Yukteswar said that a complete Yuga Cycle is of 24,000 years duration, and is comprised of an ascending cycle of 12,000 years when virtue gradually increases followed by a descending cycle of another 12,000 years, in which virtue gradually decreases.[2]
The Greco-Roman philosophers knew the Yuga Cycle as the Great Year or Platonic Year, and as per the Roman philosopher Cicero, the duration of the Great Year is 12,954 years.[3] If we assume that this value is that of the precession half-cycle, then the complete cycle becomes 25,908 years, which is quite close to the scientifically measured value of the precession cycle i.e. 25,800 years.
In my book Yuga Shift, I have proposed a revised framework of the Yuga Cycle, as per which the duration of the Yuga Cycle is 25,800 years and is exactly equal to the precession cycle of the earth. This led me to explore the two competing theories of precession, namely the “lunisolar theory” and the “binary theory”. Having investigated both of them, I came to the realization that both of these theories have their own shortcomings, and do not explain the phenomenon in its entirety. I have proposed that the precession of the equinoxes is caused by the clockwise rotation of the Solar System on its axis, once in 25,800 years, as it revolves around the Galactic Center.
In this article, which is based on my book Yuga Shift, I shall explore the current theories of precession and their drawbacks, and why the proposed theory is the simplest and most elegant explanation for the precession of the equinoxes, and is perfectly aligned with the known laws of celestial mechanics.
The twelve constellations of the zodiac encircle our solar system like a giant ring, and as the earth rotates on its axis from west to east, the constellations appear to move across the sky from east to west. Moreover, as the earth moves along its orbit around the sun in an anti-clockwise direction, the position of the sun relative to the background constellation also changes every month, moving from Aries to Taurus to Gemini and so on, in course of the solar year.
In the present epoch, on the vernal equinox date of 21st March, the sun appears very close to the beginning of the Pisces constellation, near its boundary with the Aquarius constellation. This can be determined by drawing a line from the earth to the sun and extending it to the ring of fixed stars beyond. One would, therefore, expect that, every year on March 21st, when the earth reaches the same point in its orbit, the sun will appear in front of the Pisces constellation. But that’s not what happens in reality.
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| Figure 1: The zodiac constellations encircle the solar system like a giant ring. On the vernal equinox date, the Sun appears in front of the Pisces constellation. Credit: Bibhu Dev Misra. |
This slow change in the position of the equinoctial sun against the backdrop of the fixed stars is called the precession of the equinoxes or simply precession, while the cycle duration of 25,800 years is called a precession cycle. The movement of the equinoctial point due to precession takes place backwards along the zodiac from Pisces to Aquarius to Capricorn and so on.
The time that the vernal equinox sun spends in each zodiac constellation is called an Astrological Age, which is of 2150 years duration (2150*12 = 25,800 years). Over the past 2000-odd years, the vernal equinox sun has been in the Pisces constellation, and we have been living in the Age of Pisces. Today, the vernal equinox sun is near the boundary between the Pisces and Aquarius constellations, which means we are about to transition from the Age of Pisces to the Age of Aquarius.
Since the boundaries between the constellations are not precisely defined by a specific star or asterism, the exact date of transition from one Astrological Age to another is kind of hazy and subject to individual interpretation. After moving to Aquarius, the vernal equinox sun will spend 2150 years in Aquarius before moving to Capricorn. In this manner, human civilization will live through twelve Astrological Ages in a complete precession cycle of 25,800 years.
Due to precession, the Pole Star also keeps on changing over long periods of time. Currently, the North Celestial Pole of the earth (i.e. the projection of the earth’s axis in the northern sky) points to the star Polaris, which is regarded as the Pole Star. But almost 5,000 years ago the earth’s axis pointed towards the star Thuban in the constellation of Draco, which was the Pole Star of that period. In another 5,500 years, the North Celestial Pole will point towards the star Alderamin in the Cephus constellation, which will be the Pole Star of that epoch. The North Celestial Pole traces out a circle around the North Ecliptic Pole in course of the precession cycle of 25,800 years.
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| Figure 2: The North Celestial Pole traces out a circle around the North Ecliptic Pole over 25,800 years. The Pole Star at around 3000 BCE was Thuban, while in another 8000 years it will be Deneb. Source: Adapted from Tau?olunga CC BY-SA 2.5 via Wikimedia Commons. |
What is it that causes the equinox point to shift backwards along the zodiac? The current scientific explanation is that the earth behaves like a “wobbling top”, that moves backwards as it spins. This theory is officially called the lunisolar theory of precession, since the combined gravitational force of the sun and the moon are believed to be causing precession.
The Lunisolar Theory of Precession
Before proceeding, we need to understand what is meant by “equinox”. The equinox is the exact instant when earth's rotational axis is absolutely perpendicular to the sun-earth line. During an equinox, the earth’s axis neither tilts towards or away from the sun.
As per the lunisolar theory, as the earth revolves around the sun, the combined gravitational force of the sun and the moon acts on the earth’s bulge, and slightly twists the earth’s spin axis in a clockwise manner. As a result, the equinox - which is the perpendicular alignment between the earth's rotation axis and the sun-earth line - occurs slightly before the earth completes a 360° revolution around the sun. Every year the equinox occurs after the earth moves 359°59´9.72´´around the sun and not a complete 360°. In other words, the equinox occurs 50.28 arc seconds before a complete 360° revolution.
Effectively, this means that, from equinox to equinox, the earth is slipping backwards along its orbit by 50.28 arc seconds every year. This is what causes the position of the equinoctial sun to precess relative to the fixed stars of the zodiac at the rate of 50.28 arc seconds every year or 1° every 71.6 years.
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| Figure 3: On March 21st, 2023, the equinoctial Sun appeared at the border of the Pisces and Aquarius constellations. After 72 years, on March 21st 2095, the Earth would have slipped backwards along its orbit by 1°, and the equinoctial Sun may appear in front of Aquarius. Credit: Bibhu Dev Misra. |
Over a period of 25,800 years, the earth completes a retrograde motion on its own spin axis, and one retrograde orbit around the sun. This is why earth is said to behave like a “wobbling top”, that moves backwards as it spins.
In a nutshell, therefore, as per the lunisolar theory, the earth does not complete a 360° revolution around the sun from equinox to equinox, and instead comes up slightly short by 50.28 arc seconds every year, or 1° every 71.6 years. This causes the position of the equinox sun to precess relative to the fixed stars of the zodiac by the same amount.
On the face of it, the lunisolar theory sounds plausible. There shouldn’t really be any reason for us to doubt it, right? Neither did I, until I read Walter Cruttenden’s book, Lost Star of Myth and Time.[4] Cruttenden put forward convincing arguments indicating that the currently accepted lunisolar theory of precession has major flaws which do not accord with observations.
One of his interesting arguments is that the earth does not appear to precess with respect to the meteor streams within the solar system. We know that the earth passes through a number of meteor streams that intersect its orbit. The meteor streams are “rivers of debris” left behind by a comet with an Earth-crossing orbit. When the earth passes through a meteor stream, some of the meteoroids enter the atmosphere at high speeds and burn up due to friction, producing a dazzling streak of light that we call a meteor or shooting star.
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| Figure 4: The Earth passes through the center of the Perseid meteor stream on August 12th, every year. This date has not changed due to precession. Credit: Bibhu Dev Misra. |
The earth passes through these meteor streams like clockwork on specific dates of the calendar year. For instance, the Perseids peak on August 12th, the Orionids on October 21st, the Northern Taurids on November 12th and so on. There is evidence that humans have been watching meteor showers for ages. The Perseids and the Eta Aquarids have been observed for at least 2000 years, while the first known recorded Leonid event was in 902 CE.
As per the lunisolar theory of precession, the earth moves backwards along the orbit by 50.28 arc seconds every year. If that were the case, the dates of the meteor showers should have also changed over time, since the meteor streams intersect the earth’s orbit at specific points. The Perseid meteor shower peaks on August 12th, when the earth crosses stream of particles spread along the orbit of Comet Swift-Tuttle. This date should have moved almost six days since the Gregorian Calendar Reforms in 1582. But records show that it has not changed, even though the orientation of the equinoctial points relative to the fixed stars has changed in this period.
What does this mean? It means that the earth does not move backwards along its orbit as required by lunisolar precession.
While the earth does not precess relative to the fixed meteor streams, it is somewhat complicated to determine if the earth precesses with respect to other objects within the solar system such as the moon and the other planets, since they have their own motions in their respective orbits. However, as Cruttenden points out in his book, lunar rotation equations – the same numbers that are used to plot eclipse cycles – assumes that the earth goes around the sun 360° from equinox to equinox, and does not take into account the backward slippage of the equinox along the orbit, as required by lunisolar precession.
Besides, if precession were due to lunisolar forces, then shouldn’t all the other planets of the solar system - such as Jupiter with its 79 moons, or Saturn with its 82 moons - also experience precession in different amounts and directions, and therefore slip backward or move forward in their orbits every year? There is absolutely no reason to think that it is only the earth which gets affected by the lunisolar forces, and not the other planets of the solar system. However, neither the precession of the earth, nor those of other planets, are factored into the programs that compute transit times or planetary conjunctions, and yet, all of these routines function quite perfectly.
This implies that, objects within the solar system do not precess with respect to each other. Hence, precession cannot be due to the lunisolar forces twisting the earth’s axis and causing it to slip back in its orbit. Rather, precession must be due to a motion of the entire solar system. The solar system as a whole is changing its orientation relative to the fixed stars.
The Binary Star Hypothesis
Cruttenden advanced the hypothesis that that our sun may be part of a binary star system. Stars in a binary system are gravitationally bound to each other, and orbit a common center of mass. The binary companions can be of similar or differing sizes, and the orbits can be as short as a few days or as long as thousands of years. It is estimated that nearly 50% of all the stars in the Milky Way may be part of a binary or multiple star relationship. Therefore, it would not be anything out of the ordinary if our sun were to have a binary companion as well.
If the sun, along with the planets of the solar system, curved through space in a clockwise orbit around the common center of mass of a binary star system, then this will cause a change in orientation of the equinoctial points relative to the fixed stars. Thus, precession can be simply explained as an outcome of the solar system’s curved motion through space in a binary orbit.
In a binary model, the earth will not slip back along its orbit every year. Instead, it will complete a 360° revolution around the sun from equinox and equinox. Therefore, the earth will not precess relative to the local objects within the solar system, nor will the other planets precess relative to us. The binary model, therefore, takes care of the limitations of the lunisolar theory.
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| Figure 5: Two
stars in a binary system are gravitationally bound to each other and
revolve around a common center of mass. Credit: Bibhu Dev Misra. |
“We learn from Oriental astronomy that…the sun, with its planets and their moons, takes some star for its dual and revolves around it in about 24,000 years of our earth – a celestial phenomenon which causes the backward movement of the equinoctial points around the zodiac.”[5]
Sri Yukteswar, quite clearly, did not take credit for the binary theory of precession, and had explicitly stated that it was the “Oriental astronomers” he was in touch with, who subscribed to the concept of a binary system, in order to explain the phenomenon of precession. Since the binary theory of precession has not been explicitly stated in any ancient Indian book of astronomy, it was probably transmitted orally, and was never written down.
When I had first read about the binary star hypothesis in Cruttenden’s book, it seemed like a very simple and elegant alternative to the lunisolar theory. It had none of the shortcomings of the lunisolar theory, and was based on the sun having a binary companion – which was quite realistic, given that there are so many stars with binary companions out there.
However, the more I investigated this theory, the more it became apparent that the binary theory comes with its own set of flaws. A binary companion of the sun has not yet been found, in spite of extensive sky surveys. It is expected that a binary companion of the sun will be a red dwarf star or a brown dwarf star, for such stars have very low surface luminosity and are much smaller than our sun, because of which they cannot be easily spotted.
In 1984, astronomers Davis, Hut and Muller had proposed that the sun might have an unseen binary companion which could be responsible for the “mass extinction events” that occur periodically every 26 million years.[6] They had theorized that the sun’s binary companion may be in a 26-million-year elliptical orbit, which periodically disturbs the comets in the spherical Oort cloud that surrounds the solar system, with a consequential increase in impact events on the earth.
The hypothesized companion star became known as Nemesis. As per Richard Muller, Nemesis was most likely a faint “red dwarf star” with an apparent magnitude between 7 and 12, at a maximum distance of 3 light-years.[7]
This means Nemesis, if it exists, is not visible to the naked eye, since the naked eye can only detect stars with an apparent magnitude of up to 6.5. Astronomers, by that time, had already determined that there is no “visible star” (i.e. visible to the naked eye) in the vicinity of the solar system that is in a binary orbit with the sun, since the motions and distances of the nearby visible stars had been mapped out, and none of them qualify as a binary candidate.
If a binary companion in a 26-million-year orbit can be at a maximum distance of 3 light-years from our sun, then it stands to reason that a binary companion in a 25,800-year orbit, as proposed by Cruttenden, should be much closer to the sun than 3 light-years. However, the IRAS (Infrared Astronomical Satellite) in the 1980’s, the 2MASS astronomical survey conducted from 1997 – 2001, and the most recent WISE mission (Wide-field Infrared Survey Explorer) launched in 2009, which used powerful infrared telescope technology capable of detecting red or brown dwarf stars as cool as 150 kelvins out to a distance of 10 light-years from the sun, have all failed to locate a red dwarf or brown dwarf star close enough to the sun to qualify as a binary candidate. As a result, most astronomers have given up the search for a binary companion, and believe that our sun is a lone star.
In spite of this, some people may argue that, maybe, the hypothetical binary companion is a very low luminosity dwarf star or, perhaps, it is hidden inside gas clouds, which is why we can’t find it. Our ability to not find it does not mean that the binary theory of precession is incorrect. That’s fair enough. We don’t know everything that is out there.
The reason why I believe that the binary hypothesis is incorrect is because of two important reasons. The first one is that, if the solar system were to move in a clockwise orbit around the common center of mass of a binary system, then the equinoctial points would not precess a full 360° around the zodiac. Rather, the equinoctial points would oscillate between two fixed points on the zodiac. In one half of the orbit, the equinoctial points would precess along the zodiac, while in the other half of the orbit they would move in the opposite direction.
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| Figure 6: The sun-earth reference frame in a binary orbit around a common center of mass. The vernal equinox point will oscillate between two fixed points in the zodiac. Credit: Bibhu Dev Misra |
This can be easily determined by plotting the sun-earth reference frame at different points in the hypothesized orbit, and drawing a straight line from the earth to the sun and extending it to the ring of fixed stars beyond. A binary system will produce an “oscillation of the equinoxes” and not a “precession of the equinoxes”. This is not acceptable. There is no indication, whatsoever, from historical data that the equinoctial points oscillate between fixed points on the zodiac.
Another significant issue with the binary model is that, the spin axis of the earth will always point in the same direction, and will not trace out a circle around the North Ecliptic Pole, as is required of precession. As a result, the Pole Star will remain unchanged over the duration of the precession cycle, and will always be Polaris. This is not acceptable either. It is well-documented in the ancient texts that the Pole Star changes over time. Nearly 5,000 years ago the earth’s axis pointed towards the star Thuban in the constellation of Draco, which was the Pole Star of that period. Prof. R.N. Iyengar has shown that the star Thuban was known to the Vedic Indians as Dhruva; and the evidence from a number of Puranas and Yajurveda texts show clearly that, “in India, for the Yajurvedic people, Thuban was Dhruva the Pole Star c. 2800 BCE”.[8]
So, there are two primary issues with the binary hypothesis which makes it untenable. Firstly, in a binary model, there will be an “oscillation of the equinoxes” between two fixed point on the zodiac, and not precession of the equinoxes. Secondly, in a binary model, the Pole Star will remain unchanged. The binary model, therefore, cannot be treated as a valid explanation for the phenomenon of precession. It did seem like a simple and elegant option to me when I had first read about it, but, unfortunately, it falls short in key areas.
Which means, we need to look for an alternative explanation. And, indeed, there is one: a simpler model of precession that explains all the nitty-gritties without the need for any additional variables, and is perfectly aligned with our understanding of celestial mechanics.
The Solar System Rotates on it’s Axis
In general, we tend to think of the solar system as a flat, planetary disk with the sun in the center. But, the overall shape of the solar system actually resembles a giant sphere, because it is enclosed by a vast, spherical cloud of comets called the “Oort Cloud”. The inner edge of the Oort Cloud is thought to be between 2,000 and 5,000 AU from the sun (1 AU = distance from the earth to the sun). The outer edge might be 10,000 or even 100,000 AU from the sun — that’s nearly halfway between the sun and the nearest star, Alpha Centauri (which is 4.2 light-years away). Vast swarms of comet-like bodies orbit the sun in these distant regions, numbering more than a trillion, of which only around 4,000 are known to us today. The spherical structure of the Oort Cloud was deduced on the basis of the observed motions of these comets. Astronomers believe that the Oort Cloud was probably formed nearly 4.5 billion years ago, during the infancy of the solar system.
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| Figure 7: The spherical structure of the Solar System, including the Oort Cloud, resembles the internal structure of the Earth. Credit: NASA, Public Domain Image. |
It’s quite fascinating how the overall structure of the spherical solar system resembles that of the earth. The sun in the center corresponds to the solid “Inner Core” of the earth. The planetary region where planets are in constant motion corresponds to the liquid “Outer Core” of the earth, where the constant movement of liquid metal generates the earth’s magnetic field. The spherical Oort Cloud, which surrounds the solar system and extends out to a distance of nearly 2 light-years, corresponds to the earth’s mantle. The earth’s crust, which is only about 35-70 km thick, is negligible compared to the radius of the earth. And, who knows, maybe even the solar system has a thin, crust-like outer envelope that encloses the Oort Cloud?
In this analogy we find yet another instance of the macrocosm being reflected in the microcosm – a deeply held belief of so many ancient cultures. The essential patterns of the universe seem to repeat from the biggest to the smallest levels, and, once we understand how one of the levels function, it is possible to intuitively deduce the workings of the other levels.
It is common knowledge that the earth rotates on its axis once in 24 hours and revolves around the sun in 365.24 days. Scientists have also discovered that the solar system orbits around the Galactic Center once in roughly 225-250 million years. Shouldn’t we, therefore, expect the spherical solar system to rotate on its axis as it revolves around the Galactic Center?
Since all celestial bodies rotate on their axis in order to conserve their angular momentum, the same should hold true for the solar system as well. The angular momentum of any celestial body comes from the primordial solar nebula from which they formed. The probability of a celestial body forming in such a manner as not to rotate is negligibly small. Therefore, we can be more or less certain that the spherical solar system rotates on its axis as it orbits the Galactic Center.
It is known that the axis of the solar system is inclined at an angle of nearly 30° to the galactic plane. If the solar system rotates around its axis in a clockwise direction (i.e. opposite to the direction in which the earth revolves around the sun), it will appear as if the equinoctial points are precessing clockwise around the zodiac. And, if the time required by the solar system to complete one clockwise rotation on its axis is 25,800 years, it will cause the equinoctial points to slowly change their orientation relative to the fixed stars of the zodiac by 50.28 arc seconds every year, thereby causing the phenomenon called the precession of the equinoxes. Interestingly, in December 2020, the VERA Experiment used state-of-the-art telescopic measurements to determine that the distance of the earth from the central black hole is exactly 25,800 light-years![9]
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| Figure 8: The spherical Solar System rotates clockwise on its axis, once in 25,800 years, as it revolves around the Galactic Center, completing one revolution in 225-250 million years. Image not to scale. Credit: Bibhu Dev Misra, using public domain images from NASA. |
Thus, the hypothesis of a rotating solar system, which completes one clockwise rotation on its axis in 25,800 years, explains the phenomenon of precession in its entirety. It addresses all the shortcomings of the lunisolar theory of precession that we discussed earlier, as well as the flaws of the binary model, without introducing any additional variables. Moreover, it is completely aligned with the laws of celestial mechanics which requires celestial bodies to rotate on their axis in order to conserve their angular momentum. Occam’s razor states that, “the simplest solution is the most likely one”, and a rotating solar system definitely fulfills that criteria. To sum up, this is my proposed theory for the precession of the equinoxes:
The precession of the equinoxes is due to the clockwise rotation of the solar system on its axis once in 25,800 years, as it revolves around the Galactic Center.
It is my sincere hope that this new theory of precession will come to the attention of the scientific community at large and will receive due consideration.
References
[1] Surya-Siddhanta: a text-book of Hindu astronomy, tr. by. Rev. Ebenezer Burgess, ed. by Phanindralal Gangooly, University of Calcutta, 1935, Chapter 1.
[2] Sri Yukteswar Giri, The Holy Science, 1894, p. xi.
[3] Cornelius Tacitus, The Works of Tacitus: The History, Germany, Agricola, and Dialogue on orators, Vol. II, George Bell & Sons, 1889, p. 412.
[4] Walter Cruttenden, Lost Star of Myth and Time, St. Lynn’s Press, 2006.
[5] Sri Yukteswar Giri, The Holy Science, 1894, p. 13.
[6] Davis, Hut, Muller, “Extinction of species by periodic comet showers”, Nature, 1984, Vol. 308, No.5961, pp. 715–717.
[7] Richard A. Muller, “Evidence for Nemesis: A Solar Companion Star”, LBL Publications, 1985, https://escholarship.org/uc/item/3q33r0gj
[8] R.N. Iyengar, “Dhruva the Ancient Indian Pole Star: Fixity, Rotation and Movement”, Indian Journal of History of Science, 2011, Vol.46, No.1, pp. 23-39.
[9] Diane Lincoln, “Our galaxy's supermassive black hole is closer to Earth than we thought”, LiveScience, 20 December 2020, https://www.livescience.com/milky-way-black-hole-closer-to-earth.html
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