Planet pattern A planet pattern is a specific structure formed by planets and points in a birth chart. For instance when two planets are in opposition with each other and both planets form a square with a third planet, we call this pattern a T-square. When this third planet forms an opposition with a fourth planet which in turn forms squares with the first two mentioned planets, we speak of a Grand Cross. A T-square or a Grand Cross can consist of several modalities, i.e. Cardinal (action), Fixed (steadfast) and Mutual (flexible). Another planet pattern is for instance the Grand Trine. The Grand Trine is formed when 3 planets make a trine with each other. Grand Trines are divided into different elements. We have for instance the Grand Water Trine (= 3 planets in Water signs), the Grand Earth Trine (= 3 planets in Earth signs), etc. There are many more planet structures that can form a planet pattern.