The cards are laid out in 7 rows of 7 columns with 3 cards on top called crown cards. The number 7 reflects the 7 visible planets which in ancient periods were the Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn. Science is a living being and it evolves, so now the science of the cards uses a modified seven planets that reflect current knowledge of the seven most essential planets that represent human experience: Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune.