Arc

Any part of the circumference of a circle in which the distance is measured from one point to another or, astrologically the distance travelled along the ECLIPTIC by a body over a given period of time. Arc is measured in a number of different units designed for various purposes: radians, grads, revolutions or circles, hours, degrees, etc. The most common unit of arc in astronomy and astrology is the degree, of which there are 360 in a full circle. Degrees are assumed to be the arc unit throughout this work.