The zodiac system was developed in Babylonia , some 2, years ago, during the " Age of Aries ". Contemporary use of the coordinate system is presented with the choice of interpreting the system either as sidereal , with the signs fixed to the stellar background , or as tropical , with the signs fixed to the point vector of the Sun at the March equinox. Western astrology takes the tropical approach, whereas Hindu astrology takes the sidereal one.
This results in the originally unified zodiacal coordinate system drifting apart gradually, with a clockwise westward precession of 1.
For the tropical zodiac used in Western astronomy and astrology, this means that the tropical sign of Aries currently lies somewhere within the constellation Pisces " Age of Pisces ". The sidereal coordinate system takes into account the ayanamsa , ayan meaning transit or movement , and amsa meaning small part , i. It is unclear when Indians became aware of the precession of the equinoxes, but Bhaskara 2 's 12th-century treatise Siddhanta Shiromani gives equations for measurement of precession of equinoxes, and says his equations are based on some lost equations of Suryasiddhanta plus the equation of Munjaala.
The discovery of precession is attributed to Hipparchus around BC. Ptolemy quotes from Hipparchus' now lost work entitled "On the Displacement of the Solstitial and Equinoctial Points" in the seventh book of his 2nd century astronomical text, Almagest , where he describes the phenomenon of precession and estimates its value. The principle of the vernal point acting as the first degree of the zodiac for Greek astronomers is also described in the 1st century BC astronomical text of Geminus of Rhodes.
Geminus explains that Greek astronomers of his era associate the first degrees of the zodiac signs with the two solstices and the two equinoxes, in contrast to the older Chaldean Babylonian system, which placed these points within the zodiac signs. Ptolemy also demonstrates that the principle of the tropical zodiac was well known to his predecessors within his astrological text, the Tetrabiblos , where he explains why it would be an error to associate the regularly spaced signs of the seasonally aligned zodiac with the irregular boundaries of the visible constellations:.
These events can be useful, for example, to estimate the cross-sectional dimensions of a minor planet , or check a star for a close companion. The Sun's placement upon the vernal equinox, which occurs annually around 21 March, defines the starting point for measurement, the first degree of which is historically known as the " first point of Aries ".
Zodiac signs have never been used to determine the boundaries of astronomical constellations that lie in the vicinity of the zodiac, which are, and always have been, irregular in their size and shape. The use of the zodiac as a means to determine astronomical measurement remained the main method for defining celestial positions by Western astronomers until the Renaissance, at which time preference moved to the equatorial coordinate system , which measures astronomical positions by right ascension and declination rather than the ecliptic-based definitions of celestial longitude and celestial latitude.
The word "zodiac" is also used in reference to the zodiacal cloud of dust grains that move among the planets, and the zodiacal light that originates from their scattering of sunlight. In Unicode, the symbols of zodiac signs are encoded in block "Miscellaneous Symbols": .
Check out what is for you in this planetary Birthday Horoscope February 28th Birthday Horoscope February 28th, personal asctrological characteristic for those who were born on February 28th. Customer care 10am — 6pm, India. Life has always been hard for me. Follow her on Facebook! To have a successful romantic relationship, you must partner with someone who's willing to listen and learn from you and understand your busy schedule. Lots of interests keep you active and optimistic but you are easily bored and sometimes rather impatient.
From Wikipedia, the free encyclopedia. This is the latest accepted revision , reviewed on 10 November For the East Asian zodiac based on the Jovian orbital cycle, see Chinese zodiac. For other uses, see zodiac disambiguation. Further information: Former constellations.
Further information: Babylonian star catalogues and MUL. Main article: Astrological sign. Further information: Axial precession , Epoch astronomy , Sidereal and tropical astrology , Astrological age , and Ayanamsa.
A Pisces born on February 27 is symbolized by the Fish and has great empathy for others. Learn about February 27 birthday astrology. The birthday meaning for February 27 is that the gifted Piscean will have a passion and understanding for humanitarian efforts.
Astronomical symbols Chinese zodiac Circle of stars Cusp astrology Elements of the zodiac. Oxford Dictionaries. Oxford University Press. Retrieved 19 September The Signs of the Zodiac.