On the personal level, each planet in Astrology represents a faculty or function of the human being. The Moon, for example, is the capacity to feel and to react; Mercury is the capacity to reason, to communicate and to learn, and so on.
These faculties, combined with the sign they occupy, are endowed with particular characteristics and a “mode of operation”. When Mercury is in the sign of Cancer, for instance, it gives the individual a great memory (Cancer) and the ability to read the environment, placing words appropriately when speaking to others (through sensitivity).
Astrology counts as “planets” not only the planets themselves, such as Mercury and Venus, but also the Sun (a star) and the Moon (a satellite). It is only a matter of nomenclature.
The Sun and the Moon are also known as the “Luminaries”, and their importance in the astrological chart is of the first magnitude.
The importance of the Moon is far greater than that of the Ascendant sign, whose importance is overrated.