What is the difference between the zodiac constellations compared to the other constellations?

The zodiac constellations are so named because the sun passes through them at a regular time annually (one sign per month). It doesn't mean that the sun does not pass through other star signs. For example, Orion and Sirius are some of the well-known signs in the sky, but are not included in the Zodiacs. More importantly, the zodiacs function as timekeepers (eg. you know that between 22 May to 21 June the sun will pass through Gemini, thus that month will be known as the month of Gemini). Hence, the zodiacs are just 12 specially-picked star signs to represent the sun's course through the calender. Other than that, there're no other differences between them and the other star signs.What is the difference between the zodiac constellations compared to the other constellations?
The zodiac constellations are seen from our earth perspective as being situated along the path of the sun as we see it crossing our sky. This path is called the ecliptic, and the moon is also seen on this path. In actuality, the stars in the zodiac constellations are for the most part hundreds of light years distant from our solar system and, therefore, from our sun. (The two nearest stars to our sun are Alpha Centauri and Proxima Centauri, but neither star is found in a constellation of the zodiac.) So the sun does not actually move through the constellations of the zodiac, but from our perspective on earth it appears that the sun is moving through those constellations. Also, the zodiac constellations differ from other constellations in the many ways that all constellations are different: number of stars, types of stars, pattern, distance from the solar system, etc.What is the difference between the zodiac constellations compared to the other constellations?
The ecliptic is the path the sun appears to follow in the sky. The ecliptic was identified probably in the middle to late 5th century BC in Babylon and possibly Greece. The Babylonians divided the ecliptic into 12 parts. This is known as the zodiac. The zodiac is a band of 12 constellations that the moon, sun, and planets pass through every year.



The lines dividing the constellations were originally drawn along the lines of right ascension and declination in the year 1875. But because the earth wobbles on its axis like a top, the constellations drift very slowly across the sky. This is known as precession. Do not confuse this with the rotation of the earth. The rotation of the earth still preserves the direction in which the North Pole is, therefore not changing the position of the North Star. Precession actually causes the North Pole to drift, and along with it the position of the stars. This is a cycle that takes about 26,000 years to complete.This drift causes the dividers between the constellations to no longer be in sync with the lines of right ascension and declination.



Precession has also changed the zodiac. The sun now passes through 13, and not 12 constellations. Also, it is no longer in sync with the horoscopes. Now, 24, and not 12 constellations are in the zodiac, if we define it as the region within 8掳 of the ecliptic (the band in which we find the first 8 planets). Pluto is not counted because it was unknown to the ancients. Despite that, we still consider the 12 original constellations the zodiac.



Definitions:

*Zodiac: Series of 12 constellations that the sun, planets, and moon move across.



*Constellations: Groups of stars that seem to make up pictures on the celestial sphere







Zodiac denotes an annual cycle of twelve stations along the ecliptic, the apparent path of the Sun across the heavens through the constellations that divide the ecliptic into twelve equal zones of celestial longitude.

The zodiac also means a region of the celestial sphere that includes a band of eight arc degrees above and below the ecliptic, and therefore encompasses the paths of the Moon and the naked eye planets (Mercury, Venus, Mars, Jupiter, and Saturn).





Table of constellations vs. zodiac signs:

This table provides a comparison between the dates the Sun enters and passes away from the zodiac signs and constellations as defined by various specifications.



Note the ecliptic passes through a thirteenth constellation (or more, depending upon the opinions of astronomers of any given century), Ophiuchus (the serpent bearer), as already recognized in Ptolemy's Almagest, often represented by the rod of Asclepius[10]. Notably, Ophiuchus occupies an honored place along the zodiac: amidst the cluster of dust and clouds looking toward the center of the Milky Way galaxy; although not part of the constellation, Barnard's Star is located within Ophiuchus (this is one of the nearest stars to the Solar System, and it has the largest known proper motion of any star relative to the Sun).



The following table compares the Gregorian dates on which the Sun enters



* a sign in the Ptolemaic tropical zodiac;

* a sign in the Hindu sidereal system; note that the sidereal system of Cyril Fagan, introduced in 1944, is again different, with Aries beginning on April 30.

* the astronomical constellation of the same name as the sign, with constellation boundaries as defined in 1930 by the International Astronomical Union.



The dates can vary by as much as 2 days from year to year, depending on the cycle of leap years.What is the difference between the zodiac constellations compared to the other constellations?
The Sun passes through the zodiac constellations, but doesn't pass through the others. With the way the constellation boundaries were defined by the IAU in 1920, there is now a thirteenth zodiac constellation, Ophiuchus.