Synastry is the combination of two birth times and the measurement of their compatibility. It represents the relationship between two people. By measuring the interactions of the planets, a Synastry chart develops and may be interpreted similarly to a Birth Chart. A very basic term for Synastry in astrology, usually used by the beginners, is compatibility.
Synastry is the more complex form of compatibility. Instead of comparing only the Sun Signs, Synastry combines every astrological aspect in the two Birth Charts. Typically, when combining the aspects of a romantic couple, the best planets to look at are the Sun, Moon, Venus, and Mars; however, a relationship does not only consist of matching personalities, egos, attraction, and sex. Certain locations throughout the lifetime must also match, lest separation ensue, and this is where angles make their appearance in Synastry.
Parents, the Rising Sign, and Compatibility
Fortunate planets aspected positively toward the Midheaven represent the partner's helping hand in the career and reputation. Good aspects toward the Midheaven make your partner "look good", and the planet native also helps the Midheaven native gain recognition and succeed.