... Also introduces systems of time-keeping, e.g. local solar time, time zones, universal time and the international date line. ... This lesson plan supplements: "Latitude and Longitude," section #5: on disk Slatlong.htm , on the web . ... Declination is measured from the north pole, not from the equator (the way co-latitude is defined) . ... In this case, it is the line of latitude 49 degrees. ... How long is one minute of arc along a line from the pole to the equator (line of longitude)? . ...