In addition to the Earth, Astrology deals with ten planets, namely the Sun, the Moon (the two luminaries are considered planets in astrology), Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Minor celestial bodies, such as the Dark Moon, asteroids and the nodal axis, are also taken into account, and are addressed at the end of this chapter. Each planet has its precise function in the natal chart, and represents a specific energy. The planet's action is influenced by the sign it tenants. It plays out primarily in the area of life indicated by the house where it is posited.

The planets are divided into two classes: personal planets, (or fast-moving planets), and collective planets (or slow-moving planets).
The personal planets are the Sun, the Moon, Mercury, Venus and Mars. They are said to be fast-moving because it takes them a short time to travel the Zodiacal circle (from a minimum of 28 days for the Moon to a maximum of 1 year and 220 days for Mars). As they quickly shift from one sign to the other, they release their energies very differently in each individual.

The other planetsare slower and require between 12 to 249 years to travel through the entire Zodiac, depending on the planet considered. This is the reason why they are called collective planets, with the exception of Jupiter and Saturn, because their motion is faster. Collective planets remain in a sign for several years and their energies affect one or several generations. Therefore, their influence on the individual's personality is less important.

The Sun and the Moon are two valuable sources of information on the individual's basic psychology. They are of utmost importance for the interpretation of the natal chart, and are called Luminaries because they are the brightest planets.