Everything in astrology is determined by the zodiac. The sun, which is the center of the zodiac, is a big circle. There is a band within the sun that contains 12 dwellings. Each house is divided into 30 degrees and is assigned to one of three sun signs: Aries, Taurus, or Gemini. For each solar sign, a horoscope is created. The date of birth determines the sun sign. This is why almost every sign in a horoscope has a list of birthdays next to it, showing which solar sign corresponds to which birthday. There are a total of 12 sun signs: three fire, three earth, three air, and three water signs.
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What factors go into determining the zodiac signs?
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
Is there any scientific evidence that horoscopes are accurate?
Astrology is a collection of belief systems that assert that there is a connection between astrological phenomena and events or personality traits in the human world. The scientific community has dismissed astrology as having no explanatory power for describing the universe. Scientific testing has discovered no evidence to back up the astrological traditions’ premises or alleged effects.