Locating Planets in Sky Using Manual Calculations

Ashok K. Singal

Physical Research Laboratory

In this article, we describe a very simple technique to locate naked-eye planets in the sky, to an accuracy of $sim 1^{circ}$. The procedure, comprising just three steps, involves very simple manual calculations for planetary orbits around the Sun; all one needs are the initial specifications of planetary positions for some standard epoch and the time periods of their revolutions. After applying a small correction for the orbital ellipticity, appearance of a planet relative to Sun's position in sky, as seen by an observer from Earth, is found using a scale and a protractor (found inside a school geometry box).