Cycle of precession
The precession cycle , also known as the Great Year , Platonic Year or World Year , is the precession period of the earth's axis from around 25,700 to 25,800 years. During this period, the earth's axis, which is inclined to the plane of the ecliptic , precesses once around the axis through the center of the earth, which is perpendicular to the ecliptic. As a result, the spring equinox moves once through all signs of the zodiac (constellations).
Causes and numerical values
The precession is caused by the tidal forces of some celestial bodies on the rotating earth. Through the equatorial bulge , i.e. H. The earth's radius at the equator is larger than at the poles, these tidal forces cause a torque that tries to turn the earth's axis of rotation into the perpendicular to the ecliptic, more precisely under precession # precession of the earth's axis .
Contributions to the precession constant are:
- the tidal forces of the moon and sun together with 50.40 " per year, of which 30" is due to the moon
- the planetary precession of 0.12 "per year
- the geodetic precession of 0.02 "per year by general relativity .
All of these amounts are not constant. Since their changes can only be calculated to a limited extent, the precession cycle can only be estimated with an accuracy of about a century. In this sense, extrapolating the stated values to a complete cycle is speculative.
The precession drift of the signs of the zodiac compared to the constellations
The precession cycle is the time after which you count exactly one tropical year more than sidereal years . The length of these two years is subject to such inaccuracies - for such long periods of time - despite a principally exact definition that a more precise specification than to the nearest century does not seem sensible. (The numerous reasons for this are set out in the articles Tropical Year and Sidereal Year .) In addition, the speed of precession and even the opening angle of the precession cone (twice the skew of the ecliptic ) are subject to significant changes over such long periods of time.
The drift of the vernal equinox (also known as the precession defect ) correlates with the movement of the celestial pole (the projection of the earth's axis onto the celestial sphere ) : On a star map, the vernal equinox precesses on a line perpendicular to the line from the celestial pole to the ecliptic pole , which is in the center of the precession circle ( see picture ).
Instead of the vernal equinox , the rare term Aries point is used in astrology , as the vernal equinox marks the beginning of the twelve signs of the zodiac , each 30 ° sections on the ecliptic, at 0 ° of the zodiac sign Aries .
Precession is the reason for the drifting apart of the signs of the zodiac and the constellations that gave them their names. The vernal equinox or aries point is currently located in the western part of the constellation Pisces , so it is now about 25 ° from Aries. The age of this name can be estimated based on the precession speed of 360 ° in 25,750 years: depending on whether the Aries point originally marked the beginning or the middle of the constellation Aries, it should have got its name roughly 1,700 to 3,000 years ago. Unfortunately, the sources of astronomical literature in the pre-Arab period are insufficient. Precession itself is believed to have been known to Babylonian astronomers around and before 300 BC. Have been unknown; The opposite was temporarily suspected a few decades ago, but could not be substantiated sufficiently.
Despite these reservations, the precession cycle is a method in the history of astronomy and astronomical chronology for analyzing ancient celestial records. An astonishingly early root of the Chinese calendar calculation - up to around the 15th century BC BC - suspect or date the tradition of the peasant calendars, which are still in circulation, to the end of the Middle Ages .
Plato and the Platonic Year
The naming "Platonic Year" refers to the Greek philosopher Plato . In his dialogue Timaeus , however, he mainly speaks of the fact that the planets meet again in the course of long periods of time in their common beginning and spring point and thereby complete a world cycle ; the precession does not occur here. It is also emphasized that Plato could not have known anything about precession, as it was only discovered later by Hipparchus . In the case of the late antique author Macrobius , however, there is a clear indication of a link between the Great Year or World Year and the precession cycle of the stars, so that this concept is at least of late antique origin. At another point in Timaeus, Plato himself spoke of the fact that the stars systematically deviate from their locations over very long periods of time or cycles, as he claims to have learned from the "Egyptians". This indicates that he had at least a vague understanding of the precession cycle and that the assignment “Platonic year” is therefore justified.
Twelve Platonic Months
The respective constellations of an age determine a long-term development phase of mankind according to cosmological ideas of ancient origin, which in the later 20th century flowed into currents of western astrology , especially in the context of the New Age .
The Platonic year is divided into twelve Platonic months (world months , major months and world ages) of around 2150 years each. The world months are named after the twelve signs of the zodiac . The constellation in which the spring equinox is currently located gives the month of Plato its name. Seen in this light, we are currently in the Pisces month of the Platonic year.
Based on the boundaries of the constellations defined in 1930, the ecliptic now runs through thirteen constellations - namely the twelve constellations of the zodiac and the serpent bearer (Ophiuchus). When calculating the world ages, however, the section of the snake bearer is assigned to Scorpio according to old tradition, so that there are twelve constellations. Based on the traditional constellations, the Piscean Age began almost 2000 years ago and will be over with the beginning of the Aquarian Age around the year 2600, when the vernal equinox enters the constellation Aquarius. Since the constellations take up sections of different sizes on the ecliptic, they have to be averaged over 30 ° sections in order to arrive at world months of the same length. In this alignment, the sidereal 0 ° Aries point is almost exactly opposite Spica, i.e. in 2010 at 24 ° Aries in the zodiac. Due to the precession, the sidereal 0 ° Aries point will arrive on the ecliptic at 0 ° Taurus in about 6 × 72 years and will therefore be exactly 30 ° from the vernal equinox - to which the (aligned) constellation Aquarius will then move. Accordingly, the Age of Aquarius should begin around the year 2442. Other, often mentioned times are not based on the constellations - and therefore irrelevant for a theory that wants to orient itself on the constellations.
Table of dates
Through the precession, the equinoxes and the solstices move once through all the constellations in the zodiac . If one uses twelve constellations with 30 ° each, i.e. Platonic months of the same length, and a period of 25,800 years, then the values for the world months result in the yellow column of the following table. In studying the table it should be noted that "confuse apples and oranges" here have been: for the same view that the premature start of the Piscean Age around the year 50 AD on.. Not defining harmonized, astronomical constellation, must not suddenly be used as a starting point for the aligned ages. All other columns in the table show the duration of the time phases defined by the astronomical constellation borders (in the table the world months are rounded to half a century, main positions to decades):
| (in precession sequence) | 12 × 30 ° sectors | Entry into the constellation (13 sectors of different widths) |
width | in the sector | |||
| Constellation | World month | Spring equinox | Summer point | Autumn point | Winter point | sector | Duration |
| Virgin | + 12950 - 12850 |
+ 12170 - 13630 |
- 7180 | - 730 | + 5720 | 44.1 ° | 3160 years |
|---|---|---|---|---|---|---|---|
| lion | - 10700 | - 10470 | - 4020 | + 2430 | + 8880 | 35.7 ° | 2570 years |
| cancer | - 8550 | - 7900 | - 1450 | + 5000 | + 11450 | 20.1 ° | 1440 years |
| Twins | - 6400 | - 6460 | - 10 | + 6440 | + 12890 - 12910 |
27.9 ° | 2000 years |
| bull | - 4250 | - 4460 | + 1990 | + 8440 | - 10910 | 36.7 ° | 2620 years |
| Aries | - 2100 | - 1840 | + 4610 | +11060 | - 8290 | 24.7 ° | 1770 years |
| fishes | + 50 | - 70 | + 6380 | + 12830 - 12970 |
- 6520 | 37.2 ° | 2670 years |
| Aquarius | + 2200 | + 2600 | + 9050 | - 10300 | - 3850 | 24.0 ° | 1710 years |
| Capricorn | + 4350 | + 4310 | + 10760 | - 8590 | - 2140 | 28.0 ° | 2010 years |
| Sagittarius | + 6500 | + 6320 | + 12770 - 13030 |
- 6580 | - 130 | 33.3 ° | 2380 years |
| Snake bearer | + 8650 | + 8700 | - 10650 | - 4200 | + 2250 | 18.6 ° | 1340 years |
| Scorpio | + 10040 | - 9310 | - 2860 | + 3590 | 6.7 ° | 480 years | |
| Libra | + 10800 | + 10520 | - 8830 | - 2380 | + 4070 | 23.0 ° | 1650 years |
Note:
The years are to be understood as measuring points on a time scale used by astronomers . The zero point is the same as in the common year counting of our calendar . However, since measurements are taken on a scale with zero point , there can be a difference of one year in the range of v compared to the yearly counting used by historians . u. Z. occur.
Presumed connections between precession cycle and religions
The discovery of the precession cycle by the Greek astronomer Hipparchus around 128 BC. At that time BC shook the scholarly circles considerably, since the great celestial circles of the equator and the ecliptic had until then been regarded as unchangeable and symbols of the eternal. However, there seems to be no evidence that this cycle was linked to speculations about the end of the world in Greek philosophy.
However, in 1989 the religious scholar David Ulansey put forward the theory that the discovery of the precession of the vernal equinox in the 2nd century BC. BC would have had a direct impact on the emergence of the Mithras cult : Mithras , who he identified with the constellation Perseus , was to a certain extent the "god of precession". Similar theses are propagated by Peter Joseph in the first part of his conspiracy-theoretical YouTube film Zeitgeist .
The new religious movement Thelema also assumes a change of eons with the migration of the vernal equinox.
Web links
- The precession on astronomie.de
Individual evidence
- ↑ Joachim Krautter, Erwin Sedlmayr et al. : Meyers Handbuch Weltall , p. 49 ff., ISBN 3-411-07757-3 , especially p. 51.
- ↑ Jürgen Hamel : Concepts of Astrology . Harri Deutsch publishing house, Frankfurt am Main 2010, p. 263.
- ^ Otto Neugebauer , The Alleged Babylonian Discovery of the Precession of the Equinoxes , in: Otto Neugebauer, Astronomy and History. Selected essays . Springer Verlag, New York / Berlin / Heidelberg 1983, p. 247 ff.
- ^ Joseph Needham : Science and Civilization in China . Translated by Rainer Herbster, Ed. Edited by Colin A. Ronan, Suhrkamp, Frankfurt am Main 1984, ISBN 3-518-57692-5 .
- ↑ Gottfried Briemle: The Difference Between Zodiac Signs and Constellations. In: Oberösterreichischer Volkskalender 2002. Verlag Oberösterr. Bauernbund, Linz, pp. 71-78.
- ^ Timaeus 39d
- ↑ Franz Krojer: Something about the origin of the Platonic year. In: Astronomy of Late Antiquity, the Zero and Aryabhata. Difference-Verlag, Munich 2009, pp. 49–61. (PDF)
- ↑ David Ulansey: The Origins of the Mithraic Cult. Stuttgart 1998, pp. 68-76. Original edition: The Origins of the Mithraic Mysteries: Cosmology and Salvation in the Ancient World . Oxford University Press, New York 1991. For a review of Ulansey Thesen see in particular Roger Beck: In the Place of the Lion: Mithras in the Tauroctony . In: J. R. Hinnells (ed.): Studies in Mithraism: Papers associated with the Mithraic Panel organized on the occasion of the XVIth Congress of the International Association for the History of Religions . L'Erma di Bretschneider, Rome 1994, pp. 29-50.