When everyone got together to standardize on a single longitude 0, that of England's Greenwich Observatory was chosen. Lines of equal longitude are great circles that intersect at the poles and are called meridians. Lines of equal latitude are sometimes called parallels and are all small circles except for the equator. Celestial coordinates are a projection of the earth's coordinates onto the celestial sphere. The names have been changed to confuse astronomy 101 students.
Earthly latitude is declination on the celestial sphere.
Longitude becomes right ascension, and to be even more confusing is measured in hours rather than degrees. The celestial sphere from our location appears tilted, because we are at some distance from the north pole. For the purposes of this article I will assume Traverse City's latitude is 44 degrees. The diagram right shows the earth within the celestial sphere. If Traverse City at 44 north longitude, is at the top of the earth the horizontal ellipse is the horizon, a great circle.