Why do zodiac dates vary

What's more, the Babylonians had identified 13 constellations in the zodiac, so one of them had to be left out to match the calendar. Opiuchus was unfortunately the loser.

All of this to say, while astrology is based on constellations, it's extremely arbitrary, especially since today, the sky has shifted because of a tilt in Earth's axis. Of course, this wasn't suggesting any kind of official star sign change - it was just interesting math. But a lot of people take their zodiac signs seriously, and this was too much for some to handle. After this blog was published, rumours quickly started to spread that the US space agency had suddenly changed everyone's star signs.

Pretty much ever since, NASA has been trying to wash its hands of the matter, making it as clear as possible to the public that astrology doesn't concern astronomers. The equinox occurs about six hours later every four years to account for the leap year, which is why the date changes every four years.

Scorpio horoscope April What's in store for Scorpio in April? Aries season started on March 20 in because of the leap year, but this year it started on March Someone born on March 20 might be an Aries, but they could also be a Pisces - it all depends on the astrology for their year of birth. Your Sun sign is determined by where the Sun was which constellation it was in at your time of birth rather than the date you were born.

This is because the Sun sometimes enters a constellation on a different date… so you could be a Capricorn instead of an Aquarius!

The ephemeris is a table or data file that lets you know the calculated positions of celestial objects in the sky over time. Leap Years: Why they exist and the future without them. The Incas, for example, made constellations not from stars, but from the dark patches in the Milky Way. The number of constellations in the Western zodiac comes from the cycles of the Moon, which orbits the Earth Roughly speaking, the Sun appears against a different constellation every new Moon, the stars forming a distant backdrop to the Sun.

Though the stars are not visible during daytime, you can know what constellation the Sun is in by looking at the nighttime sky. There you will see the opposite constellation. Astrology suggests that each sign of the zodiac fits neatly into a degree slice of sky — which multiplied by 12 adds up to degrees. In actuality, this is not the case, as the constellations vary a great deal in shape and size. For example, the Sun passes through the constellation Scorpio in just five days, but takes 38 days to pass through Taurus.

This is one of the reasons astrological signs do not line up with the constellations of the zodiac. The gravity of the Moon and Sun pull on the bulge, which causes the Earth to wobble like a top.

This movement alters the view of the zodiac from Earth, making the constellations appear to slide to the east, roughly a degree per human lifetime.

Though slow, precession was discovered with the naked eye by Hipparchus of Nicaea around B. In ancient times, the vernal equinox — or the first day of spring — was in Aries.