Ptolemy's catalog in the " Almagest ", which is derived from Hipparchus's catalog, is given in equatorial coordinates : in his commentary on Eudoxos he provides stars'polar distance ( equivalent to the declination in the equatorial system ), right ascension ( equatorial ), longitude ( ecliptical ), polar longitude ( hybrid ), but not celestial latitude.
12.
This determines the seasonally based tropical zodiac which takes its name from the Greek word ???????? " tropikos " : of the turning, because it is set by the turn of the seasons and, being subject to Capricorn ) are described as the'tropical signs', since these are the places where the Sun'turns'its direction in celestial latitude, ( thereby defining the terrestrial circles of latitude known as the Tropic of Cancer and the Tropic of Capricorn ).
