A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Select the first letter of the word from the list above to jump to appropriate section of the glossary. If the term you are looking for starts with a digit or symbol, choose the '#' link. - X - (empty) Back to Top - Y - (empty) Back to Top - Z - zenith The point directly overhead in the sky. zodiac The constellations through which the Sun appears to travel through in one year's cycle, located upon the ecliptic. While these constellations are of varying sizes (and have moved their positions somewhat over the millenia), the zodiac can be said to be split into twelve signs of equal size (a relatively more recent development than the concept of the zodiac itself, which was originally based on the positions of the actual stars and constellations). Back to Top - # - (empty) Back to Top