Astrologers in India and abroad claim that their ancient discipline of study is to be recognized as a branch of science. The issue was resolved in Europe long ago. As early as the fourteenth century, a clear distinction had been drawn between astronomy and astrology, the first regarded as a science, the second as an art. Previously astrology itself was supposed to be of two kinds:
(a) Natural astrology - the calculation and foretelling of natural phenomena, such as the measurement of time, fixing of Easter, prediction of tides and eclipses, and of meteorological phenomena, and
(b) Judicial astrology - the art of judging the reputed occult and non-physical influence of the stars and planets upon human affairs. (Oxford English Dictionary, 'Astrology')
Since the end of the sixteenth century, natural astrology became a part of astronomy while astrology meant judicial astronomy alone.
How can astrology be admitted as a branch of science? Science, by definition, is a systematized body of knowledge, based on observation and experiments, which can be verified by further observation and experiments conducted under similar or simulated conditions, and from the results of these some laws can be formulated which may be applied in practice. Astrology fails to satisfy these basic requirements. It is based on an imaginary concepts of the wheel of the zodiac, consisting of twelve constellations, Aries, Taurus, Gemini etc. Astronomy now recognizes nearly ninety constellations.
According to astrology, the orbits of the six planets (the Earth, Mercury, Venus, Mars, Jupiter, and Saturn), the Sun, the Moon, and the two imaginary 'planets', Rahu and Ketu, pass through this imaginary arc. All this was based on naked-eye observation and sheer ignorance of the existence of other planets in our own solar system. The very ideas of the 'nine planets' (navagraha-s) has been proved wrong. The Sun is a star, not a planet; the Moon (of the Earth) a mere satellite; and there are other planets like Uranus, Neptune, and Pluto.
Another characteristic of science is that it is ever progressive. New observations and discoveries necessitate modifications of what had so far been known. For example, the geo-centric concept which held sway since times immemorial had to give place to helio-centric one propounded and proved by Copernicus, Galileo and Kepler. Astrology, on the other hand, is a closed system. The invention of the telescope and more sophisticated device of observation revolutionized the whole of old astronomy. Astrology, however, remained unaffected. Some astrologers do claim that they have incorporated the new findings in their own calculations. By saying so they also admit their own texts are hopelessly inadequate and need drastic revision.
Science attempts to find out the casual relationship between two events. The cause is to be an invariable, unconditional and immediate antecedent of the effect that follows. So there has to be different causes for different effects. And the two events— one that precedes and the other that follows— must be inter-related. Astrology, however, believes that there is one and only cause behind such diverse events as childbirth, scoring high marks in examinations, happy marriage, increase in wealth, etc. If one cause, the influence of planets, could account for everything on earth, life would be uncomplicated indeed.