Although the signs are based on the Constellations which are created by objects outside our solar system, the planets within our system are also important in the interpretation of an astrological chart. The Planets move independently within the solar system, each planet having a different cycle around the sun. Although technically the planets do interact with each other with their gravitational pull, the paths they travel around the sun would be solitary without their individual attendant moons. There is still much debate in the astrological community about tiny cold Pluto, and even smaller Chiron at the outer reaches of our solar system. Some consider them nothing more than proto planets, two large rocks and not significant enough to be considered a planet. There are many astrologers who have added the “new” planet Chiron in their interpretations. For our purposes in charting we do not use Chiron as we believe her potentials are not yet fully understood enough to rely on them with a degree of certainty.
Modern astrology uses the planets within our solar system and their individual aspects to each other (and your location) to interpret the charts. With so many variables we know now (because the Universe is ever expanding) that there is less than a one in four billion chance of any other person having the same horoscope, or that particular pattern in the stars in direct relation to their place of birth. In other words, even Twins’ natal reports will be a little different. One may even be born in one sign and one in another. (It is entirely possible for a mother to give birth to a daughter at 11:58pm on the 20th of April, making the daughter an Aries. Then, at 12:24 she gives birth to the younger twin, another daughter identical to her sister in every biological way, but different in her chart entirely because she is born after the stroke of midnight, literally the next day from her older sister, but still in a different sign. The younger sister is technically a Taurus.) It should be noted that contrary to popular belief, an individual born on the cusp is either one sign or the other, rare is the child that is born exactly at the stroke of midnight and on the cuspal date!