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.”
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What factors influence your zodiac sign?
The sign in which the sun was at the moment of your birth determines your zodiac sign. Using the wisdom of astrology to determine a person’s zodiac sign is the first step toward drawing major conclusions about them, understanding their character, and even making meaningful predictions about their lives.
Use the form below if you don’t know your zodiac sign. Scroll down and select a sign to learn more about its distinctive qualities.
What goes into the creation of the zodiac signs?
Babylonian astronomers split the ecliptic into 12 equal “signs” at the end of the 5th century BC, analogous to 12 schematic months of 30 days each. The first known celestial coordinate system was created when each sign contained 30 degrees of celestial longitude. According to contemporary astronomical estimates, the zodiac was first used between 409 and 398 BC, during Persian dominance, and most likely within a few years of 401 BC. Unlike modern astrologers, who place the beginning of the sign of Aries at the position of the Sun at the Northern Hemisphere’s vernal equinox (March equinox), Babylonian astronomers fixed the zodiac in relation to stars, placing the beginning of Cancer at the “Rear Twin Star” (Geminorum) and the beginning of Aquarius at the “Rear Star of the Goat-Fish” ( Capricorni).
Since Babylonian times, the time of year when the Sun is in a certain constellation has altered due to equinox precession; the point of March equinox has moved from Aries to Pisces.
They formed a perfect system of reference for making predictions about a planet’s longitude since they were divided into 30 equal arcs. However, Babylonian observational measurement techniques were still in the early stages of development. They measured the position of a planet in relation to a group of “normal stars” near the ecliptic (9 degrees latitude) as observational reference points to aid in planet placing inside the ecliptic coordinate system.
A planet’s location in Babylonian astrological journals was usually stated in terms of a zodiac sign alone, rather than particular degrees within a sign. When degrees of longitude were given, they were stated in terms of the 30th degree of the zodiac sign, rather than the continuous 360 ecliptic. The positions of prominent astronomical phenomena were estimated in sexagesimal fractions of a degree in astronomical ephemerides (equivalent to minutes and seconds of arc). The daily locations of a planet were less important in daily ephemerides than the astrologically significant times when the planet moved from one zodiac sign to the next.
Who is the creator of the zodiac?
According to NASA, the Babylonians had already constructed a 12-month calendar based on the phases of the moon when they created the zodiac. Despite the fact that they identified 13 constellations that make up the zodiac, they decided to leave one out so that the zodiac signs would coincide better with their 12-month calendar.
But, before all of you Aries, Cancers, and Leos start making fun of your new Ophiuchus friends, keep in mind that the addition of this 13th constellation shifts every zodiac sign’s time frame slightly, which means that, while I’ve loved my life as a textbook Pisces, I discovered that I’m now an Aquarius after doing my research. (Gasp!)
Although 3,000 years old, this information reappeared this year when NASA disclosed scientific data regarding the Earth’s axis, which has moved and no longer points in the exact same direction as it previously did, affecting the amount of time each constellation is visible in the sky.
The astrology community (and Twitter) went crazy, and many ardent followers assumed NASA was involved “added a sign to the zodiac, causing havoc with the signs we’re all familiar with. That, however, is not the case. NASA omitted an astrological symbol from the design. They wrote a Tumblr blog entry about it “I’ve just done the math. If you want to point the finger, it should go to the ancient Babylonians for leaving Ophiuchus out of the picture in the first place.
