How Are The Zodiac Constellations Determined

Early astronomers witnessed the Sun passing through the Zodiac signs in a year’s time, spending roughly a month in each. As a result, they determined that each constellation covers 30 degrees of the ecliptic.

However, due to a phenomenon known as precession, the positions of the constellations we see now have changed.

The zero point of the Zodiac used to designate the beginning day of spring in the Northern Hemisphere. The vernal equinox happens when the ecliptic and celestial equator collide, according to astronomers.

The zero point existed in Aries around 600 BCE, and it was known as the “first point of Aries.” (See Figure 1). The constellation Aries covered the first 30 degrees of the ecliptic; Taurus covered the next 30 degrees; Gemini covered the next 60 degrees; and so on for all twelve constellations of the Zodiac.

The Earth wobbles around its axis in a 25,800-year cycle, which ancient astrologers were unaware of. The gravitational attraction of the Moon on Earth’s equatorial bulge causes this wobble, known as precession.

This wobble has led the junction point between the celestial equator and the ecliptic to migrate west along the ecliptic by 36 degrees, or nearly one-tenth of the way around, over the past two and a half millennia. This indicates that, in relation to the stars beyond, the signs have moved one-tenthor almost a month around the sky to the west.

For example, persons born between March 21 and April 19 are considered Aries. During much of that time, the Sun was no longer in the constellation of Aries. The Sun is actually in the constellation of Pisces from March 11 to April 18! (See Illustration 2) See also Figure 3, which depicts the equinox precession from 600 BCE to 2600 CE.

The dates when the Sun is truly within the astronomical constellations of the Zodiac, as defined by contemporary constellation borders and corrected for precession, are listed in the table below (these dates can vary a day from year to year).

When precession is taken into consideration, your zodiac sign will most likely be different. And if you were born between November 29 and December 17, your zodiac sign is one you’ve never heard of before: Ophiuchus! After Scorpius, the eliptic crosses across the constellation of Ophiuchus.

Visit the Birthday Sky program to view what the sky looked like on your birthday and to learn more about your “true zodiac sign.”

Constellations Image Gallery

Which constellations are considered zodiac constellations?

First and foremost, you have our permission to refer to yourself as a Lupus or a Lyra. People form attachments to a variety of constellations, not just those in the “zodiac.” Out of the 88 zodiac constellations officially classified by the International Astronomical Union, we acknowledge 13 of them. The Zodiac constellations are the ones that the Sun appears to travel through throughout the year. Of However, because the Earth revolves around the Sun and hence the Sun’s position relative to the background stars changes constantly, this motion is illusory.

The Sun appears to be travelling through Virgo the Maiden right now. The Sun will enter Libra, the Scales, at the end of October. The Sun then travels through Scorpius the Scorpion, Ophiuchus the Serpent Charmer, Sagittarius the Archer, Capricornus the Seagoat, Aquarius the Water Bearer, Pisces the Fish, Aries the Ram, Taurus the Bull, Gemini the Twins, Leo the Lion, and finally back to Virgo the Maiden, where the cycle begins again.

The Sun happened to pass through these thirteen constellations because they were oriented in such a way. We could change Earth’s orbit so that the Sun seems to pass through different constellations if we wanted to (and had supernatural powers). Lupus and Lyra, on the other hand, cannot be zodiac constellations because the Sun does not “travel through” them.

If the Sun was in that constellation when you were born, you were termed a “Virgo” or “Leo.” The astrological calendar, on the other hand, does not account for precession. The constellations aligned along the Sun’s path, called the ecliptic, shift stations slowly over time, by about one degree every 73 years, as the Earth’s poles precess over a 26,000-year period. The dates associated with the zodiac by astrologers were valid roughly 2,000 years ago. On the first day of Spring, for example, the Sun was in Aries. It is now in the sign of Pisces. As a result, astronomers continue to refer to the “First Point of Aries” on the first day of Spring (Vernal Equinox).

Why were the zodiac constellations chosen?

The 12 signs of the zodiac, as mentioned in a horoscope, are inextricably linked to the Earth’s motion through the sky. The constellations that point out the path that the sun appears to take during the year provide us with these indicators. Dates in a horoscope may appear to match to when the sun travels through each constellation. They don’t always agree, though, because astrology and astronomy are two separate systems. Plus, a closer look at the Earth, the sun, and the stars reveals that the zodiac is more complicated than you might think!

The sun’s motion through the constellations

The sun appears to pass in front of numerous constellations as Earth revolves the sun. The sun’s position in relation to distant background stars drifts in an easterly direction from day to day, much how the moon appears in a little different spot in the sky each night. It’s not as if the sun isn’t moving. Its movement is totally fictitious, owing to Earth’s own rotation around our star.

The sun appears to be in front of, or “in,” different constellations throughout the year. The sun appears in Gemini one month and Cancer the next. The dates in the newspaper’s horoscope indicate when the sun is in a specific astrological sign. For example, the sign Aries is represented by the period between March 21 and April 19. However, your astrological sign does not always indicate which constellation the sun was in when you were born.

Why the zodiac constellations don’t always align with astrological signs

We need to know a little bit more about how the Earth moves to explain why constellations no longer coincide with their respective signs. We must also discuss how we measure time.

Time is a fiendishly difficult concept to grasp, especially if we insist on using the sun and stars as our point of reference. For better or worse, our calendar is based on the seasons. The day the sun appears at its most northerly point in the sky is June 21, the approximate date of the summer solstice north of the equator and the winter solstice south of the equator. The North Pole is most inclined towards the sun at the June solstice.

The fact that the North Pole does not always point in the same direction as the background stars complicates things. Our world whirls around like a top. The Earth, like a top, wobbles! The North Pole traces a circle on the celestial sphere due to the Earth’s wobble. The wobbling is slow; it takes 26,000 years to complete one rotation. However, as time passes, the effect becomes more pronounced.

The direction of the Earth’s axis drifts somewhat throughout the course of one orbit around the sun. This means that the location of the solstice along our orbit changes by a very modest amount. The solstice occurs around 20 minutes before one full trip in front of the background stars!

Our drifting calendars

Because we base our calendar on the solstices and equinoxes (and astrologers on the signs), the Earth does not complete an orbit in a single year. The tropical or seasonal year is really a fraction of a second shorter than one full orbit (sidereal year). This means that the sun’s position in relation to the stars on any particular day varies throughout the year. For example, on June 21, a very small amount of snow falls.

However, after 2,000 years, the sun will be in a completely other constellation!

The sun was nearly halfway between Gemini and Cancer on the June solstice 2,000 years ago. The sun was between Gemini and Taurus on the June solstice fourteen years ago. In the year 4609, the June solstice point will move from Taurus to Aries, leaving Taurus behind.

When humanity formed the present Western zodiac some 2,000 years ago, the signs were roughly aligned with their respective constellations. However, the steady wobble of the Earth’s axis has led the solstice and equinox locations to shift around 30 degrees westward relative to the constellations in the intervening ages. Signs and constellations are currently around one calendar month off. They’ll be approximately two months away in another two thousand years or so.

Modern constellations and the zodiac

To make matters even more complicated, unlike astrological signs, constellations are not all the same size and shape. For the most part, the stars that make up a constellation are not physically related. They’re simply based on patterns that our forefathers noticed when they looked up at the sky, trying to make sense of it all.

The International Astronomical Union (IAU) established the constellations as sky regions, not only star patterns, in 1930. They established the boundaries we use today as a result of this. These current constellations are based on those introduced in the second century CE by Greek astronomer Ptolemy. He, in turn, took them from Babylonian scriptures dating back thousands of years. Throughout history, several societies have seen patterns in the sky that are unique to them. Some constellations are shared by many cultures (Orion is a good example), but not all.

There are actually 13 constellations that lay along the path of the sun, based on the present borders. Ophiuchus, the Serpent Bearer, sits between Sagittarius and Scorpius and is not mentioned in any horoscope. The signs stay stable in relation to the solstices and equinoxes, while the solstices and equinoxes shift westward in relation to the constellations or backdrop stars.

While the zodiac isn’t a fantastic predictor of love, fortune, or health, it is an excellent tool for better understanding the sun’s, Earth’s, and even the cultures that have come and gone on our small planet. The zodiac signs, which are drawn from constellations that line the path of the sun in the sky, trace Earth’s orbit and wobble and serve as a reminder of astronomy’s humble beginnings.

Bottom line: While you may identify the term zodiac with astrology, it also has a prestigious role in astronomy. The 12 constellations that make up the zodiac are located along the sun’s annual motion across the sky.

What criteria are used to select constellations?

Constellations are clumps of stars that form a pattern. The constellations seen at night are determined by your location on Earth and the season. Long ago, constellations were given names based on things, animals, and humans. Constellations are still used by astronomers today to label stars and meteor showers.

How are constellations named and recognised in the first place?

How do constellations get their names? The majority of our knowledge of constellation names comes from ancient Middle Eastern, Greek, and Roman cultures. They recognized star groupings as gods, goddesses, animals, and story characters.

Who was was charge of assigning constellations?

Astronomy is the study of everything in space from a scientific standpoint. Astronomers and other experts know that stars thousands of light-years away have little impact on human activities on Earth.

Astrology, on the other hand, is a different story. It is the idea that the locations of stars and planets can have an impact on human events. It isn’t regarded as a science.

The outside of the Star Finder is adorned with some strange markings. These symbols represent some of the zodiac constellations. What is the zodiac, and what makes these constellations unique?

Consider a straight line drawn from Earth to the sun, then out into space, far beyond our solar system, to the stars. Then imagine Earth traveling around the sun in its orbit. During one complete voyage around the sunor, one year, this imaginary line would spin, pointing to different stars. The zodiac is made up of all the stars that are close to the imaginary flat disk fanned out by this imaginary line.

The zodiac constellations are essentially the constellations that this imaginary straight line points to during the course of a year.

A constellation is a collection of stars that resembles a dot-to-dot jigsaw. If you connect the dots, that is, if you apply your imagination, the picture will resemble an object, an animal, or a human. Orion, for example, is a constellation that the Greeks thought looked like a huge hunter with a sword slung around his waist. These stars may not be related at all, other than the fact that they form a pattern in the Earth’s sky.

Even the nearest star is nearly incomprehensibly far away. The shapes and positions of the constellations in Earth’s sky change relatively slowly due to their great distance. They barely alter during the course of a human lifetime.

Over 3,000 years ago, the Babylonians lived. As though cutting a pizza into 12 equal slices, they split the zodiac into 12 equal halves. They chose 12 zodiac constellations, one for each of the 12 “slices.” As the Earth revolves the sun, the sun appears to pass through each of the zodiac’s 12 signs. Because the Babylonians already had a 12-month calendar (based on moon phases), each month had its own section of the zodiac.

However, there were 13 constellations in the zodiac according to ancient Babylonian tales. So they chose Ophiuchus to be the one to be left out. Even yet, several of the chosen 12 didn’t fit cleanly into their designated pie slice and crossed over into the next.

A birthdate between roughly July 23 and August 22 meant being born under the constellation Leo when the Babylonians originally invented the 12 signs of the zodiac. The sky has shifted 3,000 years later because the Earth’s axis (North Pole) no longer points in the same direction.

Because the constellations vary in size and shape, the sun spends varying amounts of time aligned with each one. For 45 days, the line from Earth to the sun points to Virgo, while for only 7 days, it points to Scorpius. The Babylonians ignored the fact that the sun travels through 13 constellations, not 12, in order to match their 12-month calendar. Then they allotted the same amount of time to each of the 12 constellations.

Is astrology based on any scientific principles?

Is astrology accurate? Reading horoscopes is a popular pastime, but is there any scientific evidence that they are accurate?

When you’re enticed by a familiar interruption and your willpower weakens, problems can occur.

Every day, up to 70 million Americans consult their horoscopes. At least, that’s what the American Federation of Astrologers claims. According to a Pew Forum on Religion & Public Life poll conducted twenty years ago, 25% of Americans believe that the positions of the stars and planets have an impact on our daily life. In 2012, the General Social Survey indicated that 34% of Americans think astrology is “extremely” or “kind of scientific,” with the percentage of individuals who think astrology is “not at all scientific” dropping from two-thirds to about half.

Astrology is the concept that astronomical phenomena, such as the stars over your head when you were born or the fact that Mercury is retrograde, have the potential to influence our daily lives and personality traits. Of course, this is distinct from astronomy, which is the scientific study of celestial objects, space, and the physics of the cosmos.

A particular facet of astrology, the foretelling of a person’s future or the provision of daily counsel via horoscopes, is gaining in popularity. The Cut, for example, recorded a 150 percent rise in horoscope page views in 2017 compared to 2016.

Clearly, a lot of people are trying to figure out how to read the stars for guidance. Understanding the positions of the stars is the foundation of astrology, which appears to be a scientific discipline in and of itself. Is there any scientific evidence that astrology has an impact on our personalities and lives?

But, since I still have five minutes of this six-minute podcast to fill, let’s take a look at how astrology has been put to the test.

Who came up with the idea for the 12 constellations?

APIN was employed in tandem with a system of 12 zodiacal constellations inherited from Babylonians by Greek astronomers. The system of 12 zodiac constellations was also utilized in the magical and astrological treatise BRM 4.20, which dates back to the latter third of the fourth century BC, according to the article.

How do horoscopes come to be?

An astrologer must first determine the exact time and location of the subject’s birth, or the start of an event, in order to generate a horoscope. At the same time, the local standard time (adjusted for daylight saving time or wartime) is transformed into Greenwich Mean Time or Universal Time. In order to compute the ascendant and midheaven, the astrologer must translate this to the local sidereal time of birth. The astrologer will then examine an ephemeris, a set of tables that displays the positions of the Sun, Moon, and planets for a given year, date, and sidereal time in relation to the northern hemisphere vernal equinox or fixed stars for a given year, date, and sidereal time (depending on which astrological system is being used). The astrologer then adds or subtracts the difference in longitude between Greenwich and the location in issue to obtain the true local mean time (LMT) at the birthplace, which shows where planets would be visible above the horizon at the particular time and location. Planets hidden beneath the earth’s surface are also depicted in the horoscope.

When two people meet and start a relationship, astrology practitioners typically create a composite chart using the aforementioned procedure. The composite chart, according to astrologers, will reveal the nature and purpose of the partnership.

The horoscope is divided into 12 sectors that circle the ecliptic, beginning with the ascendant or rising sign on the eastern horizon. The houses are the 12 sectors, and there are several techniques for calculating these divisions. Since the 19th century, tables of dwellings have been issued to make this otherwise difficult work easier.