# What are the RAs of the boundaries between traditional zodiacal signs?

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I'm trying to figure out at what right ascension (RA) - not celestial longitude - the sun enters the various traditional (Western) astrological signs of the Zodiac; but I can't figure out how to calculate this.

What are the right ascensions of the boundaries between traditional zodiacal signs along the ecliptic?

TL;DR: Calculating the right ascension (i.e. converting from ecliptic to equatorial coordinates) requires some spherical trigonometry, but fortunately there are internet tools that will do this, such as here. The resulting RA coordinates are: Aries 0h 0m 0s; Taurus 1h 51m 39s; Gemini 3h 51m 16s; Cancer 6h 0m 0s; Leo 8h 8m 44s; Virgo 10h 8m 21s; Libra 12h 0m 0s; Scorpio 13h 51m 39s; Sagittarius 15h 51m 16s; Capricorn 18h 0m 0s; Aquarius 20h 8m 44s; Pisces 22h 8m 21s.

Explanation and background

Since traditional (Western) astrology uses the same tropical year as astronomical celestial coordinates, the tropical zodiac commences with Aries at 0˚ longitude on the ecliptic, and each subsequent zodiac sign (NB not the constellation, which is different) commences exactly 30˚ further along the ecliptic. So, the zodiac division of Taurus is from 30.00˚ to 59.99˚, Gemini from 60.00˚ to 89.99˚, and so on. It's then just a matter of converting ecliptic longitude to celestial coordinates (right ascension).

Further useful information on the relationship between the ecliptic and right ascension can be found in Mike G's answer to "Effect of the obliquity of the ecliptic / tilt of the Earth on the equation of time".

Both the traditional tropical zodiac and modern astronomical coordinates are based on the northern hemisphere vernal equinox. This starting point, also known as the First Point of Aries, is one of the two points at which the celestial equator crosses the ecliptic.

When Hipparchus defined the First Point of Aries in 130 BCE, it actually aligned with the border between the constellations of Pisces and Aries. However, due to the precession of the equinoxes, the tropical zodiac's starting point has a retrograde movement along the ecliptic at the rate of one degree every 71.5 years. As a result, the First Point of Aries is currently deep in Pisces! Using the current official IAU constellation boundaries, the point of 0h RA will cross into Aquarius in the year 2597, so we have quite some time to wait for the "Age of Aquarius".

Note that not all astrological traditions are based on the tropical year. Hindu astrology, for instance, is based on the sidereal zodiac - i.e. it aligns permanently with the visible stars, regardless of the Earth's axial precession. Some modern Western astrologers also use a sidereal zodiac, in which sidereal Aries currently begins on 15 April.

It is going to depend on where you draw the lines, but they're not equally spaced… and it also depends on whether or not you include Ophiuchus. Since they're not evenly spaced, it's not like you can start with a point on the ecliptic and calculate an even spacing for them.

## The Truth About Astrological Signs

Sometimes, when there is a slow news day, I think the mainstream media likes to recycle a story that previously caused some controversy in order to "stir the pot" again and get another rise from the general public. That certainly seemed to be case about a month ago, when a news story began furiously circulating about how NASA had just changed the signs of the Zodiac.

I mean there it was, on page three of the Sept. 27 New York Daily News:

"News that NASA updated astrological signs for first time since Babylonians devised them some 3,000 years ago rocked everyone's world. Even casual zodiac followers have flown off the handle and gotten all, well, Scorpio-like. The recognition of Ophiuchus, that 13th sign, only added to the chaos. But NASA had reasons for renovations. The night sky today doesn't look like it did three millennia ago, the Earth's axis has changed and Ophiuchus was originally omitted for neatness' sake. It's always been there."[Insight Astronomy Photographer of the Year 2016: Amazing Photos]

That first line about how "NASA updated astrological signs for the first time since Babylonians devised them some 3,000 years ago" almost made me spit out my morning cup of tea. And sure enough, this "cosmic revelation" went viral. By that same evening, virtually every TV news broadcast devoted a few minutes to how the astrological signs had suddenly been changed.

## What are the RAs of the boundaries between traditional zodiacal signs? - Astronomy

Signs of the Zodiac: What Are They?

There are so many misconceptions about the Sidereal signs that a good question to ask at the beginning is, “What is a sign of the Zodiac? Tropical astrologers measure the signs from the spring equinox, which marks the point each year where the ecliptic intersects the equator, but what is the source of the influences that supposedly make up the traits of the Tropical signs?

The Sidereal zodiac is measured in relation to the fixed stars. A primary difficulty with this zodiac is that astrologers throughout the world don't agree on which stars define the Sidereal zodiac. The government of India has finally settled on Spica as the 180° point of the zodiac—the boundary point between Virgo and Libra. The Fagan-Bradley school of astrology uses Aldebaran and Antares to mark 15 degrees of Taurus–Scorpio. The debate concerning the exact boundaries of the Sidereal signs is on-going, and finding a final answer isn't necessary to grasp the focus of this article.

A common misconception is that the sidereal signs are the same as the constellations. Anyone who studies a sky map knows this isn't so. Like the Tropical signs, the sidereal signs are all 30° in length, while the actual constellations vary a great deal. The first part of sidereal Aries, for example, actually contains the stars of the constellation of Pisces, including the brightest star, Al Risha (the knot of Pisces) and the Northern Fish.

The Zodiac: A Brief Historical Perspective

We know that the twelve sign zodiac first appeared in Mesopotamia. In the Neo-Assyrian period the positions of the planets and the moon were referred to in relation to 17 constellations. Not all of these were in the ecliptic. These constellations were described as gods standing in path of the moon . It was understood that the Sun and planets also moved through these 17 constellations. Some of these constellations were:

The Bull of Heaven (Taurus)
True Shepherd of Anu (Orion)
Scales (Libra)
Tails (Pisces)

The 7 th century B.C.E. saw the introduction of mathematics into astrology and astronomy. The catalyst for the development of mathematical astrology was the invasion of Babylon by the Persians. Sometime between 630 and 450 B.C.E. the planets became established in zodiacal signs rather than constellations. The ecliptic was divided into twelve equal signs which replaced the older series of 17 constellations. The twelve zodiacal signs were:

 NAME SYMBOL NAME SYMBOL The Hireling A ram The Scales Scales (?) Bull of An (The Stars) A humpbacked bull The Scorpion A scorpion The Great Twins Two figures with weapons pa.bil.sag (pa) A hippo-centaur The Crab A crab The Goat Fish A goat fish The Lion A Lion The Great Figure with streams of water flowing over his shoulder The Furrow A maiden holding a stalk of grain The Tails(the Field) Swallow and fish

The twelve signs were further divided into dodekatemoria, or 12 sections of 2 ½ degrees each. The zodiac at this period in history was plainly sidereal, and the exaltations and triangles (four groups of three signs each now associated with the four elements) were in place. The places of the exalted planets were general areas of the constellations.

Astrology as we know it today was born from a fusion of Egyptian ideas with Babylonian astronomy. The invading armies of Alexander the Great arrived in Mesopotamia in October of 331. The Hellenistic period which followed saw astrology developing with a scientific emphasis. Hipparchus (c190-120 B.C.E.) discovered the precession of the equinoxes. Ptolemy (100?-170? C.E.) stated flatly that the zodiac began at the vernal equinox.

For several hundred years centered around the B.C.E./C.E. junction the state of the zodiac appears to be a study in confusion as astrologers combined the symbolism of the stars and constellations with zodiac signs that were measured from various points on the ecliptic. Eventually the zodiac confusion (which most astrologers at that time may have been unaware of) settled down. The fixed sidereal zodiac took root in India, and the west adopted the mathematically secure Tropical zodiac measured from the vernal point.

Back to our original question: Although we know how the two zodiacs are measured—from the spring equinox or from one or more fixed stars, what are the sources of sign characteristics? In other words, What is a sign of the Zodiac?

Early astrological writers treated signs and constellations in different ways. Signs were treated in terms of patterns and were grouped into trigons (triangles) or squares. They were divided alternately into masculine and feminine categories. Sometimes these divisions were termed nocturnal or diurnal . Constellations and stars were treated individually their attributes were not noted as being direct influences of the signs.

For many centuries it has been comfortable for astrologers to think of signs as boxes or static blocks of space that begin and end at exactly 30 degree intervals from each other each sign was assumed to have a constant influence within its boundaries. The late English astrologer, John Addey, has forced us to re-think this belief. He reminds us that static blocks of space don't exist in the universe rather, we live in an environment of constant motion and change. Everything and every being in the universe responds to cyclic influence. The universe is pulsating, rhythmic, moving. Why then should not the ecliptic or zodiacal path of the earth/sun also respond to the pulse of the universe?

According to Addey, rather than being seen as fixed blocks of space, the zodiacal signs may be more accurately described as a continuing series of waves that culminate and wane at regular intervals. Various sign influences would ebb and flow in intensity. Addey termed this wave principle harmonics , and believed that any observed sign regularities could be explained in terms of the harmonic concept.

The work of Michel and Françoise Gauquelin has given us evidence that diurnal harmonics exist in the individual horoscope. Why then cannot zodiacal harmonics also exist, culminating and waning at specific points within a 12-fold pattern? In Addey’s thought, the nearest we can come to describing the traditional twelve signs in terms of harmonics is the sixth harmonic (six waves) within the zodiacal circle. The peaks would correspond to the odd signs and the troughs to the even signs. (Addey, p. 57)

However, other harmonic patterns, such as the elements, have been observed by astrologers. This means that sign polarity can more accurately be defined by two 6th harmonic waves, each wave having its own beginning and culmination points. This idea explains the Indian concept of the division of signs into solar and lunar halves (Hora) : the first (rising-to-a peak) half of male signs comes under the Sun while the second (falling) half is ruled by the Moon. The reverse is true for female signs.

What we call a “sign” may be in part the culmination area of basic harmonic waves which divide evenly into the number twelve: Twelve is the lowest common multiple of 2, 3, 4 and 6, and so embraces the symbolism of these numbers. Dividing four into twelve gives us the three modes of four signs each (cardinal, fixed and mutable), and dividing three into twelve gives us four sets of three elements each.

Addey noted that the characteristic timber of different musical instruments arises from the ways in which the sub-harmonics of their notes combine. (Addey, p. 21) Figure 1 below shows how the primary harmonics peak and join each other to form the zodiacal sign of Leo . Note that the element of fire reaches its nadir in Gemini (and other air signs), while the fixed quality becomes nil between mutable and cardinal signs.

Hindu astrology implicitly recognizes a wave action in the zodiac in its use of harmonic charts as well as in the doctrine that a planet positioned near the junction of two signs is critically placed and unstable in its action. Planets near the beginnings of signs are said to be in their infancy and weak. Planets near the ends of signs are said to be in a state of old age with little power to do good.

Virginia Beach clairvoyant, Edgar Cayce, spoke of sign cusps as indicating “the rising of one influence and the submerging. of another. ” (801-1) He said that people having cuspal emphasis would find themselves under two sets of influences, resulting in a pull in different directions. Although the term cusp technically refers to a culmination point, the term has been used in astrological literature to mean the junction point between two signs or houses. Cayce particularly emphasized the cusp at the spring equinox. Hindu sidereal astrology recognizes the importance of the equinox and solstice points, but they are not used in measuring signs of the zodiac. In the Tropical zodiac, the equinox points mark the beginnings of zodiac signs.

Since static signs cannot exist in the theoretical sense, we can partly define an area of the zodiac that seems to produce a specific effect as the culmination area of primary harmonics . This concept explains polarity, the four elements, and the three qualities. Harmonics aside, we are still left with the possible (or probable) influence of the actual constellations and individual stars. We can also ask by what process the symbolism of planetary lords and exaltations relate to signs of the zodiac.

If the astrological zodiac is indeed a construct based on harmonics, the question still facing us is, “Do sign waves correlate with the solstices and equinoxes, or do they flow in relation to one or more critical stars? As Addey states:

The great zodiac problem is: What determines the phase? How are we to decide at what points in the circle the maximum effect occurs in any particular case?” (Addey, p. 176)

“The important issue is not one of the zodiac as such, but of the significant focus or foci in the ecliptic from which effects, as represented by the harmonics of the circle, are generated.” (Addey, p. 197)

The Tropical zodiac has a precise starting point at the northern hemisphere spring and southern hemisphere fall equinox. But what about the sidereal zodiac? A zodiac requires a fiducial point on the circle from which measurements are made. Various measurements from specific stars were used in Mesopotamia to designate the initial points of zodiac signs. However, these stars were not exactly 30 degrees and zero minutes from each other, which leaves us with a zodiac with hazy sign boundaries.

Of the bright stars that lie close to the ecliptic, Spica is virtually the only candidate for a fiducial star that is located near a sign junction, and this junction happens to be just at the center of the sidereal zodiac between Virgo and Libra. Perhaps of greater interest is that Spica is only minutes in longitude from bright Arcturus to the north. Edgar Cayce gave great importance to Arcturus as evidenced from these quotes from his readings:

“For Arcturus is the way, the door out of this system.” (2454-3)

“Not that the Sun as the center of the solar system is all there is. For the entity has attained to that realm even of Arcturus, or that center from which there may be the entrance into other realms of consciousness.” (2823-1)

“Arcturus is that which may be called the center of the universe, through which individuals pass and at which period there comes a choice of the individual as to whether it is to return [to earth] or to pass on to [other systems]. (5749-14)

“Arcturus is that junction between spheres of activity as related to cosmic force, and is that about which this particular sphere of activity rotates. ” (263-15)

So, at least according to Edgar Cayce, the degree of Arcturus (and Spica) is of critical importance for the evolution of mankind. Does the longitudinal degree of Spica–Arcturus—the junction point between Virgo and Libra— mark a critical wave emanation point for the Sidereal zodiac? Just opposite this point is zero degrees of Aries.

Finding the Point of Wave Emanantions

Since it is the peaks and troughs of waves that may define signs, how do we know exactly where high and low points occur in the zodiacal circle? The exact phasing of zodiacal waves, if they exist, cannot be easily observed. The key areas in question are the current areas of overlap between the Tropical and Sidereal zodiacs. (See figure 2 below) These areas are approximately five to seven degrees in length depending on the ayanamsa (the difference between the Tropical and Sidereal zodiacs) and the modern year in question.

If the final degrees of a Tropical sign behave more like the following Tropical sign in relation to polarity, the modes and elements, then this is evidence for a sidereal zodiac of wave influences. If the early degrees of Sidereal signs resemble the preceding sign, then this points to harmonic waves linked to the equinox points.

Because the area of overlap between the zodiacs at present is only 1/5 of a sign, and harmonic effects would diminish toward the ends of signs, it is very difficult to judge which zodiac might be the most accurate when only personal opinion and observation are used for measurement. It may be that the characteristics of polarity, the modes and trigons cannot be observed at all for the first five degrees and final five or six degrees of a sign. This is precisely the current overlap of the Tropical and Sidereal zodiacs.

In summary a sign of the zodiac may be made up of:

(1) Harmonics which correlate with polarity, trigons and qualities. (Note: Other harmonics may exist such as the 27 Indian nakshatras or the 28 medieval lunar mansions.)

(2) Influences which relate directly to the domicile lords and exalted planets in signs via a cosmic connection whose operation we don't understand at present.

(2) Individual stars which may affect variable degrees depending on how bright the star is. A bright star such as Spica may influence a two degree area whereas the effect of a small dim star may be limited to less than a degree.

(3) The possible overall effect of the actual constellations. This would cause a blending across signs. For example Virgo extends into two thirds of sidereal Libra. The actual constellation of the scales falls in the last ten degrees of Libra. Are the first two thirds of Libra different than the last third? (Or is there a noticeable difference between early and later Tropical Scorpio—the current constellational boundary of Virgo and Libra?)

If effects come from the actual stars and/or constellations, then the meanings of Tropical signs will shift over the centuries, whereas sidereal signs will remain stable. Another possibility is that harmonics correlate with signs measured from the equinox, but the effects of planetary domiciles belong to the sidereal zodiac. This would mean that over the centuries the effects of polarity, trigons and qualities would phase in and out of the sidereal signs while the sign effects which correlate with the planets would remain stable.

The easiest solution would be if harmonics were tied to a particular fiducial star such as Spica then the effects of the stars and constellations would remain stable over the centuries in a sidereal zodiac. In the Tropical zodiac the stars and constellations will always shift over time in relation to the signs. It is still an unknown how the domicile lords operate in the zodiac, though I've found the correlation much easier to make in the sidereal zodiac. A few Tropical astrologers have actually told me that they don't believe there is any correlation at all between planets and zodiac signs!

At this time we are still faced with centuries of unanswered questions about the zodiac. Until research supports a particular zodiac, individual astrologers will remain attached to their favored zodiac, and controversy will continue in the astrological world with some astrologers claiming that all the zodiacs work. In my opinion this isn't a tenable solution to the zodiac question.

Therese Hamilton
May 20, 2004

Addey, John. (1976) Harmonics in Astrology. Greenbay, WI: Cambridge Circle, Ltd.

Baigent, Michael. (1994) From the Omens of Babylon: Astrology and Ancient Mesoptamia. Arkana, Penguin Books.

Ballard, Juliet Brooke. (1979) The Hidden Laws of the Earth. Virginia Beach, VA: A.R.E. Press

The Edgar Cayce Readings, Volume 18. (1985) Astrology - Part 1. Virginia Beach, VA: Association for Research and Enlightenment (ARE).

Gauquelin, Michel. (1978) Cosmic Influences on Human Behavior. New York: ASI Publishers, Inc.

Hand, Robert, Compiler. (1995?) Chronology of the Astrology of the Middle East and the West by Period. Arhat Publications

Hand, Robert. The History of Astrology - Another View. Arhat Publications (Internet)

Hand, Robert. On the Invariance of the Tropical Zodiac. Project Hindsight, 1997 (Internet)

Ulla Koch-Westenholz. (1995) Mesopotamian Astrology. Denmark: Museum Tusculanum Press

## What are the RAs of the boundaries between traditional zodiacal signs? - Astronomy

The astronomy behind astrology

• Do you know that what you consider to be your zodiac sign, might not be correct?

In this page, I try to give a scientific explanation to these questions and on the way, let you discover your real zodiac sign. I start by introducing some astronomical concepts which I hope will give you some insight about the geometry and the physics of the rotation of the Earth around the Sun and the apparent movement of the objects on the sky.

I like to point out that the main purpose of this page is to show the astronomical facts behind what we call zodiac signs, and I just did it for fun! (after all, being an astronomer I am always asked about other people's horoscopes!). It is not my intention to discuss in depth the validity of astrology or its predictions, however I give my personal opinion as an astronomer, if you're interested.

The zodiac and astrology are common concepts among many countries in the Western civilization. Surveys show that around 90% of the population know their zodiac sign, and almost half read their horoscopes regularly. Astrology columns help to sell millions of newspapers and magazines and are a popular topic in television and radio programs. Although only a small percentage actually admit to take horoscopes seriously, the vast majority of the people do not know the astronomical concepts behind their birth sign.

Astrology originated in Mesopotamia around 3000 years ago. The ancient Babylonians performed methodical observations of the night sky and built great observatories where priests would study the skies, and the celestial bodies that they believed controlled life and events on Earth. In those times, objects in the sky were believed to be affixed to transparent celestial spheres and their motions were thought to be a result of the motion of these spheres as they revolved around the Earth. Groups of bright stars were observed to form prominent patterns in the night sky called constellations, which have been historically ascribed to mythological figures. The early astronomers recognized that constellations appeared and disappeared with the change of the seasons throughout the course of a year. In the same way, the Sun, Moon and planets were observed to move in relation to the fixed background of stars, or constellations. The Earth travels in space as it revolves about the Sun in a planar orbit that is approximately circular. If one drew a line from the center of the Earth through the center of the Sun, that line would "draw" a large plane in the heavens as the Earth orbits the Sun. This large plane is called the ecliptic plane, as is shown in Figure 1.

Figure 1
The ecliptic plane and the ecliptical coordinate system

Figure 2
The equatorial plane, the annual seasons and the equinoxes

Figure 3
The band of the zodiac and the apparent position of the constellations with respect to the Earth-Sun system

Based on their observations of the night sky, ancient astronomers determined that during the daytime, the Sun would appear to "enter" or pass through different constellations throughout the year. Because of their perspective from Earth, they observed that the Sun, the Moon and all the planets visible with the naked eye seemed to pass in the course of a year through a region in the sky occupied by twelve specific constellations. Those constellations are the ones that we would intersect if we extend the ecliptic plane out into space. These twelve constellations were called the Zodiac. Many ancient people believed that a person's behavior, emotions, and fate were heavily influenced by the time of that person's birth i.e. that person's zodiac sign.

The zodiac constellations, as envisioned by ancient astronomers, were ascribed specific patterns that resemble the shapes of animals and human beings. The constellations of the zodiac actually form an imaginary belt in the sky that extends about eight degrees above and below the ecliptic plane as is shown. As we look at the position of the zodiac constellations at any given time of the year, the Sun is between the Earth and one of these constellations, as Figure 3 shows.

Vernal and autumnal equinoxes

We are familiar with the Earth's equator because of our knowledge of geography. If we could extend the earth's equator into space so that it could be viewed against the background of stars, we would be able to see what in astronomy is called the celestial equator. Because the Earth's axis of rotation is tilted with respect to the ecliptic by 23.5∫, the celestial equator and the ecliptic do not lie on the same plane, but cross each other at an angle of 23.5 degrees as is shown in Figure 2. The two points in the sky where these two planes cross are called the equinoxes. We call the vernal equinox the intersection point where the Sun, in its apparent motion against the background stars along the ecliptic, crosses the celestial equator from south to north, usually occurring around March 21 st . Similarly, we call the autumnal equinox the intersection point where the Sun, in its apparent motion against the background stars along the ecliptic, crosses the celestial equator from north to south, usually occurring around September 21 st . The first day of Spring then corresponds to the vernal equinox and the first day of Fall corresponds to the autumnal equinox. During the time of the equinoxes, we on the Earth experience twelve hours of day and twelve hours of night.

The precession of the equinox

Figure 4
The precession of the Earth around its axis

The Earth's rotation on its axis has caused the Earth's shape to diverge from a sphere, and has caused the Earth's equatorial regions to bulge out. Because the Earth's equator is tilted with respect to the orbital plane of the Earth around the Sun, the Earth's equatorial bulge is also tilted with respect to the plane along which the Sun and Moon travel. The Moon and the Sun exert a gravitational drag on the Earth's equatorial bulge, trying to pull the Earth's equatorial region to be aligned with the ecliptic plane. This pull, along with the rotational motion of the Earth on its axis, the revolution of the Earth around the Sun, and the revolution of the Moon about the Earth, cause the Earth to wobble about its axis of rotation, similar to the motion of a spinning top. This motion is called precession. It is the wobbling of the equatorial plane that causes the line of the intersection of the equatorial and ecliptic planes to move. As mentioned above, the intersection of these two planes determine where on the zodiac our spring and fall equinoxes occur. This line of intersection is said to precess or move around the zodiac because of the wobble.

Figure 5
Circular path that the north equatorial pole describes due to the precession of the Earth

Figure 4 shows a schematic of the Earth's precession, this effect gradually changes where on the zodiac the equinox points fall. It takes about 2150 years for the equinox to travel 30∫ or 1/12 th of the ecliptic. This precession means that the spring equinox was just entering Pisces 2000 years ago and it is about to enter the constellation of Aquarius (that is the reason why many astrologers say that we are going to start the Aquarius epoch).

An extension of the Earth's axis out into space traces out a conical figure with a time cycle or period of 26,000 years. The Earth's precession implies that although Polaris is currently the star above our north pole, in about 13,000 years Vega will become our north star only after yet another 13,000 years, will the north pole will once again point towards Polaris, as shown in Figure 5. Therefore, because of the Earth's precession, the constellation which is behind the Sun nowadays is actually different from the one predicted by astrologers.

Ophiuchus, the 13 th constellation of the zodiac

The constellations of the zodiac at the present

Unlike the zodiac signs in astrology, the astronomical constellations vary widely in size. If we think of the sky as a great sphere, the areas that different constellations cover can be drawn fairly accurately. There are a number of days of the Earth's orbit when the Sun is between our planet and any one of the zodiacal constellations. Since each constellation is of different size and since the ecliptic passes through larger or smaller portions of each constellation, and the speed of the Earth around the Sun varies along its orbit, the Sun is between the Earth and each zodiacal constellation for varying periods. For example, more days (44 days) are spent with the Sun between the Earth and the largest constellation, Virgo, than are spent with the Sun between the Earth and the smallest constellation, Scorpius (7 days).

The boundaries of all the constellations in the sky were set by the International Astronomical Union (IAU) in 1930. This was essentially a mapping exercise to make the work of astronomers more efficient. 2000 years ago, there were 12 constellations in our zodiac. At present our ecliptic passes through the boundaries of 13 constellations, the usual 12 and a new one known as Ophiuchus (or Serpentarius). Ophiuchus is depicted as a man supporting a serpent, the interposition of his body divides the snake into two parts, Serpens Caput and Serpens Cauda. Ophiuchus, is located in a position near the center of the Milky Way galaxy amid clouds of molecular hydrogen and dust. In addition, although not part of the original constellation stars, the so-called Barnard's Star is located within Ophiuchus this object has the largest known proper motion relative to the Sun. Just as a remark, within a few hundred years the ecliptic will no longer pass through Scorpius but will also include the constellation of Orion.

Most astrologers use a different system to determine the size of our zodiacal constellations. The ecliptic (which is also the name to the apparent path of the Sun on the sky, which creates a circle of 360∫) is simply divided up into twelve equal segments (of 30∫) corresponding to the same amount of months in the calendar, just by convenience, marking the start of the year cycle at the so-called first point of Aries, i.e. the point on the sky where the ecliptic and equatorial planes intersect, i.e. the vernal equinox. This point occurred 2000 years ago in the constellation of Aries, but nowadays this occurs in the constellation of Piscis, making this constellation the start-point of the current zodiac solar system.

The following table provides the dates at which the Sun is located within the boundaries of a specific zodiac constellation as defined in 1930 by the International Astronomical Union, i.e. the periods of the real zodiac signs.

The dates can vary by as much as 2 days from year to year, depending on the cycle of leap years. The solar zodiac column indicates the actual dates when the Sun is located within the boundaries of the named constellation. If you are on the boundary between any two signs and you want to know your real sign (together with your ascendent and descendent signs, defined below), use the free software called Stellarium indicating the date, time and location of birth and it will give you a nice sky chart of your birthday through a nice interface.

## Twelve Signs of the Western Astrology

According to natural distribution, stars are divided into many regions of different sizes, each called a constellation. Connecting all bright stars in a constellation with lines, different images in the shape of animals and objects are formed. People named each constellation according to its shape. The International Astronomical Union divided the sky into 88 constellations with precise boundaries, making every star belonging to a particular constellation.

Seen from Earth, the sun moves slowly in the Celestial Sphere and passes through constellations, forming a large circle for a year. This circle is called Ecliptic. The Ecliptic is divided into twelve equal portions (each equivalent to 30 degrees) each portion was named after the closest constellation. All these twelve portions were called Ecliptic Constellations, according to which western horoscope theories developed.

The astrologists divide a year into 12 periods, during each period the sun being in a constellation area. So everyone has a corresponding zodiacal sign according to the period his / her birthday lies in. The 12 signs are Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius and Pisces. People believe that different sun signs of the zodiac present different characteristics and talents.

## Constellations

It is important to distinguish the zodiacal signs from the constellations associated with them, not only because of their drifting apart due to the precession of equinoxes but also because the physical constellations by nature of their varying shapes and forms take up varying widths of the ecliptic, and so the sun is not in each constellation for the same amount of time. [ 18 ] :25 Thus, Virgo takes up fully five times as much ecliptic longitude as Scorpius. The zodiacal signs, on the other hand, are an abstraction from the physical constellations designed to represent exactly one twelfth of the full circle each, or the longitude traversed by the Sun in about 30.4 days. [ 19 ]

There have always been a number of "parazodiacal" constellations that are also touched by the paths of the planets. The MUL.APIN lists Orion, Perseus, Auriga, and Andromeda. Furthermore, there are a number of constellations mythologically associated with the zodiacal ones : Piscis Austrinus, The Southern Fish, is attached to Aquarius. In classical maps, it swallows the stream poured out of Aquarius' pitcher, but perhaps it formerly just swam in it. Aquila, The Eagle, was possibly associated with the zodiac by virtue of its main star, Altair. Hydra in the Early Bronze Age marked the celestial equator and was associated with Leo, which is shown standing on the serpent on the Dendera zodiac. Corvus is the Crow or Raven mysteriously perched on the tail of Hydra.

Due to the constellation boundaries being redefined in 1930 by the International Astronomical Union, the path of the ecliptic now officially passes through thirteen constellations: the twelve traditional 'zodiac constellations' plus Ophiuchus, the bottom part of which interjects between Scorpio and Sagittarius. Ophiuchus is an anciently recognized constellation, catalogued along with many others in Ptolemy's Almagest, but not historically referred to as a zodiac constellation. [ 20 ]

The technically inaccurate description of Ophiuchus as a sign of the zodiac dates to the 1970s. This drew prominent media attention on 20 January 1995, following an announcement on the BBC Nine O'Clock News that "an extra sign of the zodiac has been announced by the Royal Astronomical Society". [ 21 ] Investigation into the source of the story revealed there had been no such announcement, and that the report had merely sensationalized (perhaps for the purposes of promoting a forthcoming BBC astronomy program) the 67-year-old 'news' of the IAU's decision to alter the number of designated ecliptic constellations. [ 22 ] The assertion that Ophiuchus constitutes an astrological sign periodically resurfaces in the media, due to a failure to appreciate that the irregular astronomical demarcation of the thirteen ecliptical constellations does not relate to the separate frame of reference provided by the equally-spaced twelve-fold longitude division of the ecliptic into zodiacal signs. [ 23 ]

## What are the RAs of the boundaries between traditional zodiacal signs? - Astronomy

There is a short poem which helps to remember the signs of the zodiac. It is two short couplets that include all the signs, albeit not in proper order:

The ram, the bull, the heavenly twins,

And next the crab, the lion shines,

The virgin and the scales,

The scorpion, archer, and the goat,

The man who holds the watering-pot,

And fish with glittering scales.

I n astronomy , the zodiac is a circle of twelve 30° divisions of celestial longitude that are centered upon the ecliptic : the apparent path of the Sun across the celestial sphere over the course of the year. Historically, these twelve divisions are called signs . The signs are named after the major constellation in each division.

Astrology is the belief in a connection between the cosmos and terrestrial matters has played an important part in human history. It’s bunk, of course. Western astrology is based on ancient star tables, and gives us these twelve signs and symbols:

The dates of the astrological zodiac do not correspond to astronomical observation the traditional star charts are horrible out of date.

Due to the constellation boundaries being redefined in 1930 by the International Astronomical Union , the path of the ecliptic now officially passes through thirteen constellations: the twelve traditional 'zodiac constellations' plus Ophiuchus (the serpent bearer) , the bottom part of which interjects between Scorpio and Sagittarius. Ophiuchus is an anciently recognized constellation, catalogued along with many others in Ptolemy 's Almagest , but not historically referred to as a zodiac constellation.

Based on actual celestial observation and astronomical redefinition, these are the actual modern dates of the zodiac:

Aquarius: Feb. 16 – March 11

Sagittarius: Dec. 18 – Jan. 18

Ukrainians were not believers in astrology, but did follow the constellations and have their own names for them.

According to my handout and the Brody book, zodiac symbols can also be placed onto a Brody pysanka. The symbols used are not the western ones used by the Romans, but the Ukrainian ones that represent their names for the constellations. Which calendar you choose to use is up to you. In Ukrainian, Ophiuchus is Змієнесець: I do not know if he has his own symbol.

I have listed here, for each sign/constellation, the following information:

and included a medieval representation of the zodiac sign, as well as the Brody symbol. SOme names are fairly similar, while others are hugely different. Then again, the Roman’s Great Bear (and English Big Dipper) is our Big Wagon.

## The Difference Between Tropical and Sidereal Astrology

With Tropical, the zodiac signs are placed relative to the sun’s position on the ecliptic (denoted by the equinoxes and solstices, which is what defines the seasons).

With Sidereal, the zodiac signs are mapped to the constellations and fixed stars.

Depending on which system is used the story that is revealed – and the predictions that are made – can become drastically different!

This poses a problem, doesn’t it? With such contrary results, is it possible that these two systems of Astrology can co-exist? Do they provide unique perspectives on the same situation, or is one more accurate than the other?

My conclusion based on years of study (though I remain open) is the fixed stars have very little – if nothing at all to do with astrology. Astrology is based on celestial phenomena within our own solar system exclusively (and likely alignments with the Galactic Centre which our solar system revolves around).

As with Sabian Symbols, I have never found fixed stars to hold much truth at all – and certainly sidereal astrology, being based on these fixed stars, is an inaccurate co-ordinate to accurately map consciousness on Earth.

Let’s explore more about Astrology and see what we can find!

##### Astrology History Lesson

Archaic forms of Astrology have been with us for many millenia beginning with the observation that the Sun returned to its original position every 12 lunar cycles.

Tropical Astrology was officially codified approximately 2000-2500 years ago, with knowledge pioneered by the Ancient Babylonians, Egyptians and Greeks.

These cultures used the Spring Equinox as the reference for the zero-point or the beginning of the Zodiac Cycle.

The Spring Equinox was a particularly celebrated Event to our ancestors, representing the New Year, when fertility and light returns after Winter.

Two thousand years ago, at the Spring Equinox, the Sun occupied the space in the sky that roughly corresponded with the Constellation of Aries. Thus the first sign was named ‘Aries,’ and the remaining eleven signs were similarly named after easily-recognizable constellations along the ecliptic plane.

The fixed stars were easily-visible reference points to identify the twelve segments of the sky in order to advance their study of the cosmos. The Signs are given meaning from the Seasons! The qualities and energetic signatures of the Zodiac Signs are connected with the Sun as it journeys along the Ecliptic.

##### What is the Ecliptic

The Ecliptic is a Great Circle around the the Earth. All planets move within this narrow band in the sky.

From our Geo-Centric perspective on Earth, it appears as though the Sun , Moon and other Planets revolve around our planet on this plane.

When the Moon’s orbital path intersects with the Sun’s Ecliptic we experience Eclipses.

Every year, the Sun completes a sine-wave pattern over the Earth.

The waveform is caused by the angle of the Earth as it orbits the Sun, and this creates the Earth’s Seasons.

The sun’s path is evenly split into twelve, 30-degree segments over the Earth, totaling 360 degrees.

The Greeks introduced their knowledge of Astrology to India approximately two millenia ago, in the Yavanajātaka.

This is why both Western and Vedic systems share the same Zodiac Cycle and Names.

##### What is the Zodiac?

Both Western and Vedic Astrology use the Zodiac .

The Zodiac is a Blueprint for the Evolution of Consciousness.

The Zodiac Cycle begins at Genesis, Birth (Aries) and finishes at Culmination, Apotheosis (Pisces).

As we reach the culmination of the cycle, consciousness is reborn and we repeat the cycle all over again. This sequence is timeless, and represents a universal pattern for Evolution in Life, applicable throughout the whole universe!

##### Tropical Astrology

The Planet Earth is split into the Temperate and Tropical regions.

The Tropics are at the center of the Earth, and the Tropics’ boundaries are defined by the Tropics of Cancer and Capricorn. It is along the Tropics, on the equator, that the Ecliptic resides and the sun and planets travel, hence the name Tropical Astrology.

Tropical Astrology is a local science operating predominantly (or exclusively) within our solar system. The Climate and the Seasons are caused by the Sun and Earth’s relationship.

The Sun is the engine of our solar system, and the brightest luminary in our sky.

Tropical Astrology is brought to life by the Sun’s path through the Zodiac.

Tropical Astrology divides the Zodiac Signs relative to the 4 Seasons.

• At the Vernal and Autumnul Equinoxes, the Sun is at the centre of the Earth on the Equator, and we experience Equal day and night.
• At the Summer and Winter Solstice, the Sun reaches either its maximum or minimum distance from the equator, and we experience either the longest or shortest day.

These potent earthly events carry emotional, spiritual and physical influences. These all factor into the archetypes and energies of the Zodiac Signs.

##### Sidereal Astrology

Sidereal on the other hand, places a heavy emphasis on the influence of stars outside our solar system, dividing the signs relative to the fixed stars.

Fixed stars appear as a ‘stationary’ backdrop for the moving Planets.

However, from our perspective on Earth, these fixed stars do actually move! This phenomenon is called the Precession of the Equinoxes.

###### The Precession of the Equinoxes

The Earth is not a perfect sphere, and has an uneven distribution of mass, particularly around the equator. The Sun and Moon’s gravitational influence acts on the Earths equatorial bulge, causing the Earth to slowly wobble on its rotational axis.

What this means is from our perspective, the background of stars and constellations move slowly in the opposite direction of the planetary bodies. The fixed stars move at a rate of 1 degree every 72 years.

Roughly every 2160 years, a new Constellation sits at the seat of the Spring Equinox.

For example, at the Spring Equinox in 2020, the Sun is not in the constellation of Aries, it is on the cusp of the constellation of Pisces and Aquarius.

It takes approximately 26,000 years for the backdrop of stars to make a complete cycle and return to their original location. This is known as the Great Year.

Sidereal astrologers take the Precession of fixed stars into account, and adjust all charts for this phenomenon.

###### In summary, the difference between Tropical and Sidereal is:

– Tropical references the relationship between the Sun and Earth.

– Sidereal references the influence of stars from billions of light years away.

##### Similarities Between tropical and sidereal

No matter what system you use, the same planetary alignments occur in both systems, and this means Western and Vedic astrologers can talk about the impacts together.

It’s common to see astrologers incorporating wisdom from both systems. For example, Western Astrologers using the lunar nodes and fixed stars, or Vedic Astrologers including outer planets such as Uranus, Neptune and Pluto – this shows the potential for union within these systems.

##### IS tropical or sidereal MORE ACCURATE?

Determining the validity of the Tropical vs Sidereal Systems requires a lot of prerequisite knowledge:

• You will need a strong understanding of astrology’s basic principles
• Understanding the Planets’ Characteristics and Meanings
• Understanding the Planetary Conversations and Aspects
• Understanding the energetic expression of each Zodiac Sign
• Factoring in Progressions, Current Transits and Natal Transits
• You will also need Open-mindedness and Curiosity.
• We must let the Truth guide us without dogma or biases, traditions and cultures influencing our decisions.
##### How to Study the Differences?

Astrology is the quest for understanding our true nature as Infinite creators. You know you best!

Be authentic and real with yourself, and study your Natal Chart.

1. Filter your chart through the lens of Tropical and Sidereal – which makes more sense? Honestly?
• Study the charts of your family and friends
• Study the charts of open and authentic artists.
• Study moments in history, both major and minor.
• Study Full Moons, New Moons, Eclipses
• Study Planetary Ingresses

It is important that we really feel deeply into the emotional signature and energetic frequency of each of these charts and the souls and experiences they represent! This is vital in this work. These questions must be asked – and must be done so over years and years of study before any concrete conclusions can be drawn!

We need many more human beings undertaking this scrupulous study – pioneering the Science of Consciousness and Astrology. This is where True Evolution lies, in multi-dimensionality.

Astrology is multidimensional because it is an umbrella for a wide array of academic AND spiritual disciplines.

For example:

• Astronomy
• Geometry
• Mathematics
• Psychology
• History and Mythology
• Shamanism and Divination
• Intuition, Emotional Healing

Both Tropical and Sidereal systems have scientific, astronomical, mathematical, theoretical basis for their efficacy. But this is not enough. Astrology is all about Vibration, Frequency and Consciousness, operating on a multi-dimensional level.

Astrology is a feelings-based craft as much as it is intellectual science, and the spiritual, emotional realm is what we need to tap into more than theory alone.

If our frame of reference and our intake of information is not aligned with reality, our decision making will also be out of alignment.

1. Does Tropical or Sidereal more accurately reveal the Psychology of a person?
2. Under Scientific Scrutiny, which system yields more accurate predictions on the future?
3. With Real-World Application, which system more Accurately Forecasts the present moment – RIGHT NOW?

Currently the two systems diverge by a measure of almost 24 degrees!

In a few hundred years, these systems will have separated by a full zodiac sign! Now more than ever the Truth will become evident, as predictions and analyses will either align with, or stray dramatically from objective reality.

The Truth will speak for itself, and, presuming people are healthily-detached from their beliefs and not under cult-like conditioning, we will begin to align with the Truth, and harmonize with Natural Law Reality – in all aspects of life actually!

Another interesting note is Western Astrology’s history is full of government suppression, occultation, outlawing, censorship, punishment and execution – while on the other hand Vedic Astrology was allowed to practice unchallenged for millenia.

##### My Personal Opinion

After studying Astrology for thousands of hours and for over a decade, my conclusion is Tropical is far more accurate than Sidereal. I personally do not give much plausibility to the validity of Fixed Stars, although I am still experimenting with these. Sidereal has never stood up to my open and critical analysis.

My grasp on Reality is proving to be aligned with Objective Truth and Natural Law. AnarkEden the Website, the forecasts I have provided, and the posts I have authored stand as testimony to my analysis on reality, which has proven to be incredibly accurate!

I am a great astrologer, and my chart is easy to interpret, especially because I have always been really true to myself and authentic.

I can easily see the inaccuracies of the Sidereal perspective in all charts I have ever read. To me it is like listening to a song in terms of musical theory, but not vibing with the emotion or music.

Tropical is scientifically, verifiably true. I encourage people to use Wholesign Tropical – it works best!

Tropical and Sidereal Tropical and Sidereal Tropical and Sidereal Tropical and Sidereal

## What are the RAs of the boundaries between traditional zodiacal signs? - Astronomy

"Aries, Cancer, Libra, Capricorn are called moveable and Cardinal: moveable, because when the Sun enters into Aries and Libra, the Weather and Season of the Year quickly varies and changes they are called Cardinal, because when the Sun enters into any of those Signs from that time we denominate the Quarters of the yeer. For from the Sun entering into Aries and Libra the Equinoctial or the Spring and Autumne arise from the Sun his entrance into Cancer and Capricorn ariseth the Solstice of Summer and Winter.

The Fixed Signs doe in order follow the Equinoctial and Tropicks and they are called fixed, for that when Sun enters into them, the season of the yeer is fixed, and we doe more evidently perceive either Heat or Cold, Moysture or Drinesse. The fixed Signes are these, Taurus, Leo, Scorpio, Aquarius.

Common Signes are constitutes between moveable and fixed, and retain a property or nature, pertaking both with the preceding and consequent Sign:"

Christian Astrology,, page 88.
W e can see many examples of the importance of the seasonal attributions of the signs of the Tropical Zodiac, for example, the exaltations of the planets. The English astrologer William Ramesey says,

Enter we shall here (as in the preceding Chapter) with the Luminaries, and first with the Sun, as being the chief light, and Fons vita, the Fountain of life the Sun then is said to be in the point of his Exaltation when he is in the 19. degree of Aries, he being then in the highest Northern point of the Ecliptick, by which all things are made to spring and flourish, the heat of weather and the length of days being increased therefore for the same reason contrary is he said to be in his Fall in Libra, it being the opposite sign in the heavens to Aries, in the which he declineth Southward, by the which the shortness of the days and cold is increased, to the hinderance of the fertility of the earth."

Astrologia Restaurata, page 69.
T he Tropical Zodiac, therefore has the advantage of being regular and orderly, part of a complex and interrelated system that is itself regular and orderly. Take away the regularity of the 12 signs and substitute 13 irregular signs and the system of aspect is thrown into confusion, the triplicities and quadriplicities are lost and the very meaning of the individual signs is thrown into question. We should also consider the fact that the Tropical Zodiac is highly effective and has been used to make precise and accurate predictions for 2,000 years. It is so highly integrated into Western astrology, even modern psychological astrology, that if one eliminates it, then one must invent from scratch, a new astrology!

## Contents

The word "constellation" comes from the Late Latin term cōnstellātiō, which can be translated as "set of stars" it came into use in Middle English during the 14th century. [7] The Ancient Greek word for constellation is ἄστρον. These terms generally referred to a recognisable pattern of stars whose appearance is associated with mythological characters or creatures, earthbound animals, or objects. [1] A more modern astronomical sense of the term "constellation" denotes one of the 88 IAU designated constellations recognized today. [8]

Colloquial usage does not draw a sharp distinction between "constellations" and smaller "asterisms" (pattern of stars), yet the modern accepted astronomical constellations employ such a distinction. E.g., the Pleiades and the Hyades are both asterisms, and each lies within the boundaries of the constellation of Taurus. Another example is the northern asterism popularly known as the Big Dipper (US) or the Plough (UK), composed of the seven brightest stars within the area of the IAU-defined constellation of Ursa Major. The southern False Cross asterism includes portions of the constellations Carina and Vela and the Summer Triangle is composed of the brightest stars in the constellations Lyra, Aquila and Cygnus.

A constellation (or star), viewed from a particular latitude on Earth, that never sets below the horizon is termed circumpolar. From the North Pole or South Pole, all constellations south or north of the celestial equator are circumpolar. Depending on the definition, equatorial constellations may include those that lie between declinations 45° north and 45° south, [9] or those that pass through the declination range of the ecliptic or zodiac ranging between 23½° north, the celestial equator, and 23½° south. [10] [11]

Stars in constellations can appear near each other in the sky, but they usually lie at a variety of distances away from the Earth. Since each star has its own independent motion, all constellations will change slowly over time. After tens to hundreds of thousands of years, familiar outlines will become unrecognizable. [12] Astronomers can predict the past or future constellation outlines by measuring individual stars' common proper motions or cpm [13] by accurate astrometry [14] [15] and their radial velocities by astronomical spectroscopy. [16]

Both the 88 IAU recognized constellations and those that cultures have recognized throughout history are essentially imagined figures and shapes with only a certain basis in the actually observable sky. [17] Many officially recognized constellations are based in the imaginations of ancient, Near Eastern and Mediterranean mythologies, but the physical reality of the Earth's position in the Milky Way still produces shapes that are connected by the human mind. [18] For instance, Orion's Belt forms a more or less visually perfect line. H.A. Rey, who wrote popular books on astronomy, pointed out the imaginative nature of the constellations and their mythological, artistic basis, and the practical use of identifying them through definite images, according to the classical names they were given. [19]

### Lascaux Caves Southern France Edit

It has been suggested that the 17,000-year-old cave paintings in Lascaux Southern France depict star constellations such as Taurus, Orion's Belt, and the Pleiades. However, this view is not yet generally accepted among scientists. [20] [21]

### Mesopotamia Edit

Inscribed stones and clay writing tablets from Mesopotamia (in modern Iraq) dating to 3000 BC provide the earliest generally accepted evidence for humankind's identification of constellations. [22] It seems that the bulk of the Mesopotamian constellations were created within a relatively short interval from around 1300 to 1000 BC. Mesopotamian constellations appeared later in many of the classical Greek constellations. [23]

### Ancient Near East Edit

The oldest Babylonian catalogues of stars and constellations date back to the beginning of the Middle Bronze Age, most notably the Three Stars Each texts and the MUL.APIN, an expanded and revised version based on more accurate observation from around 1000 BC. However, the numerous Sumerian names in these catalogues suggest that they built on older, but otherwise unattested, Sumerian traditions of the Early Bronze Age. [24]

The classical Zodiac is a revision of Neo-Babylonian constellations from the 6th century BC. The Greeks adopted the Babylonian constellations in the 4th century BC. Twenty Ptolemaic constellations are from the Ancient Near East. Another ten have the same stars but different names. [23]

Biblical scholar E. W. Bullinger interpreted some of the creatures mentioned in the books of Ezekiel and Revelation as the middle signs of the four-quarters of the Zodiac, [25] [26] with the Lion as Leo, the Bull as Taurus, the Man representing Aquarius, and the Eagle standing in for Scorpio. [27] The biblical Book of Job also makes reference to a number of constellations, including עיש ‎ ‘Ayish "bier", כסיל ‎ chesil "fool" and כימה ‎ chimah "heap" (Job 9:9, 38:31–32), rendered as "Arcturus, Orion and Pleiades" by the KJV, but ‘Ayish "the bier" actually corresponding to Ursa Major. [28] The term Mazzaroth מַזָּרוֹת ‎, translated as a garland of crowns, is a hapax legomenon in Job 38:32, and it might refer to the zodiacal constellations.

### Classical antiquity Edit

There is only limited information on ancient Greek constellations, with some fragmentary evidence being found in the Works and Days of the Greek poet Hesiod, who mentioned the "heavenly bodies". [29] Greek astronomy essentially adopted the older Babylonian system in the Hellenistic era [ citation needed ] , first introduced to Greece by Eudoxus of Cnidus in the 4th century BC. The original work of Eudoxus is lost, but it survives as a versification by Aratus, dating to the 3rd century BC. The most complete existing works dealing with the mythical origins of the constellations are by the Hellenistic writer termed pseudo-Eratosthenes and an early Roman writer styled pseudo-Hyginus. The basis of Western astronomy as taught during Late Antiquity and until the Early Modern period is the Almagest by Ptolemy, written in the 2nd century.

In the Ptolemaic Kingdom, native Egyptian tradition of anthropomorphic figures represented the planets, stars, and various constellations. [30] Some of these were combined with Greek and Babylonian astronomical systems culminating in the Zodiac of Dendera it remains unclear when this occurred, but most were placed during the Roman period between 2nd to 4th centuries AD. The oldest known depiction of the zodiac showing all the now familiar constellations, along with some original Egyptian constellations, decans, and planets. [22] [31] Ptolemy's Almagest remained the standard definition of constellations in the medieval period both in Europe and in Islamic astronomy.

### Ancient China Edit

Ancient China had a long tradition of observing celestial phenomena. [32] Nonspecific Chinese star names, later categorized in the twenty-eight mansions, have been found on oracle bones from Anyang, dating back to the middle Shang dynasty. These constellations are some of the most important observations of Chinese sky, attested from the 5th century BC. Parallels to the earliest Babylonian (Sumerian) star catalogues suggest that the ancient Chinese system did not arise independently. [33]

Three schools of classical Chinese astronomy in the Han period are attributed to astronomers of the earlier Warring States period. The constellations of the three schools were conflated into a single system by Chen Zhuo, an astronomer of the 3rd century (Three Kingdoms period). Chen Zhuo's work has been lost, but information on his system of constellations survives in Tang period records, notably by Qutan Xida. The oldest extant Chinese star chart dates to that period and was preserved as part of the Dunhuang Manuscripts. Native Chinese astronomy flourished during the Song dynasty, and during the Yuan dynasty became increasingly influenced by medieval Islamic astronomy (see Treatise on Astrology of the Kaiyuan Era). [33] As maps were prepared during this period on more scientific lines, they were considered as more reliable. [34]

A well-known map from the Song period is the Suzhou Astronomical Chart, which was prepared with carvings of stars on the planisphere of the Chinese sky on a stone plate it is done accurately based on observations, and it shows the supernova of the year of 1054 in Taurus. [34]

Influenced by European astronomy during the late Ming dynasty, charts depicted more stars but retained the traditional constellations. Newly observed stars were incorporated as supplementary to old constellations in the southern sky, which did not depict the traditional stars recorded by ancient Chinese astronomers. Further improvements were made during the later part of the Ming dynasty by Xu Guangqi and Johann Adam Schall von Bell, the German Jesuit and was recorded in Chongzhen Lishu (Calendrical Treatise of Chongzhen period, 1628). [ clarification needed ] Traditional Chinese star maps incorporated 23 new constellations with 125 stars of the southern hemisphere of the sky based on the knowledge of Western star charts with this improvement, the Chinese Sky was integrated with the World astronomy. [34] [35]

Historically, the origins of the constellations of the northern and southern skies are distinctly different. Most northern constellations date to antiquity, with names based mostly on Classical Greek legends. [10] Evidence of these constellations has survived in the form of star charts, whose oldest representation appears on the statue known as the Farnese Atlas, based perhaps on the star catalogue of the Greek astronomer Hipparchus. [36] Southern constellations are more modern inventions, sometimes as substitutes for ancient constellations (e.g. Argo Navis). Some southern constellations had long names that were shortened to more usable forms e.g. Musca Australis became simply Musca. [10]

Some of the early constellations were never universally adopted. Stars were often grouped into constellations differently by different observers, and the arbitrary constellation boundaries often led to confusion as to which constellation a celestial object belonged. Before astronomers delineated precise boundaries (starting in the 19th century), constellations generally appeared as ill-defined regions of the sky. [37] Today they now follow officially accepted designated lines of Right Ascension and Declination based on those defined by Benjamin Gould in epoch 1875.0 in his star catalogue Uranometria Argentina. [38]

The 1603 star atlas "Uranometria" of Johann Bayer assigned stars to individual constellations and formalized the division by assigning a series of Greek and Latin letters to the stars within each constellation. These are known today as Bayer designations. [39] Subsequent star atlases led to the development of today's accepted modern constellations.