The “coordinate system” in the sky is essentially an extension of the Earth’s surface-based system of latitude and longitude. There are celestial poles and a celestial equator and, just like parallels of latitude on Earth, objects are measured in degrees of declination north or south from the celestial equator. Unlike the longitude system, however, celestial objects are measured in only one direction, rather than using east and west as we do with longitude. Discover the celestial coordinate system and the Sun’s apparent path along the ecliptic in this month’s column.