A horoscope is a 2-D diagram mapping a 3-D pattern of our solar system with the planets orbiting around the central star, the Sun.
AP (Astrological Psychology) uses the 8 planets as well as the Sun and Moon. The Earth is the central vantage point for the observation of our solar system, but the Earth is not depicted in a chart drawing.
Even though the Sun is a star and the Moon is a satellite of Earth, for simplicity, they are always referred to as planets in astrology. The apparent trajectory along which the planets move is called the ecliptic which is also known as the zodiac (more about this in later lessons).
Five Layers of a Birth Chart:
Layer one: Inner most core - central circle
Layer two: Aspects - coloured lines
Layer three: Planets - Planetary symbols
Layer four: Zodiac signs - Sign symbols
Layer five: Houses - outer edge of chart
So before setting out to study the core of AP, it is important to familiarize yourself with its symbolic language first.