A Grand Cross is a planetary alignment in the astrology chart. It consists of four planets at 90-degree angles with each other and each being in a different astrological quality. Every sign of the zodiac is either cardinal, mutable, or fixed. Therefore, a Grand Cross happens when all four planets involved are in the mutable signs of Gemini, Virgo, Sagittarius, and Pisces. This brings a very different energy to the Grand Cross than say a Cardinal Grand Cross or a Fixed Grand Cross, for the mutable energy is probably the most congenial of the three, even though Grand Crosses can be challenging enough in and of themselves.