However, due to precession, the Earth has moved on its axis since then, and the dates used to identify the signs no longer correlate to the backdrop constellations that give them their names. In reality, the timeline has migrated by one sign to the west. That is to say, depending on the mathematical division of the year, zodiac sign dates roughly correspond to the position of the sun in the constellations of the signs preceding them today. (The fixed character of the signs is also why the Minnesota Planetarium Society’s 2011 argument that a 13th zodiac sign, Ophiuchus, should be added now, failed to result in a major astrological shift.)
“Previously, astrologers looked at where the sun was in relation to background constellations in general, and that almost exactly matched up with the signs of the zodiac defined by Ptolemy,” Odenwald adds.
Astrologers now base their calculations and predictions on where the planets and the sun are in relation to the 12 fixed signs, rather than where they are in relation to the constellations. According to astrology, if the sun is in the sign of Sagittarius on your birthday, you are a Sagittarius.
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What factors go into determining astrology?
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 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.
