# CHAPTER 4

# Planetary Position Coordinate System

## Introduction

This chapter describes how planets are plotted on a coordinate system. It will define the coordinate system by which we locate planets in absolute terms.

Key Concept Questions

- How does one define a planetary position?
- What is the reference point for the zodiac?
- What are the degrees of the zodiac signs?
- What is an angular coordinate system?
- What is a planet position relative to the Aries point?
- What is a planet position using a reference angle relative to its current sign?

## Planet Positions

There are 360 degrees in a circle. The Earth orbits around the Sun in a relative circle. In order to simplify the location of the Earth to the Sun, these 360 degrees were divided into roughly 12 equal signs of 30 degrees each. To track this position by degree there must be a starting or reference point that represents zero degrees. This point marks the start of the sign Aries. So zero degrees is the starting point, and it is known as the Aries point. Every 30 degrees after that marks the start of a new sign. Each sign can be defined from the Aries point. The degrees of signs from the Aries point are defined as follows: Aries, 0–30; Taurus, 30–60; Gemini, 60–90; Cancer, 90–120; Leo, 120–150; Virgo, 150–180; Libra, 180–210; Scorpio, 210–240; ...