The Sun is the giver of all life and also has an important role in astrology. The Sun mostly co-exists in harmony with all the planets and rules the sign of Leo.
Systemic aspects of its relationship to the other planets and celestial bodies is critical in determining whether the person whose horoscope is being charted will have a personality at peace or in conflict. If the aspects between them are friendly, the personality is well balanced; when those aspects are unfriendly, the native person will experience inner conflicts.
A native is considered to have been born under a dominant Sun, a “solarian”, when it is placed strongly in the natal chart, especially when it lies in its own sign of Leo and has major aspects with the Moon, the Ascendant and the Medium Coeli.
However, inferring the dominant planet requires more complex calculations, which can be done by a good astrologer or, quickly, by an algorithm which takes into consideration a large number of variables.
A person with Sun dominant will be a person of strong physique, strong will, and high confidence. She or he will attract good energies and develop a strong sense of self-respect.
However, certain aspects can skew the personality of those born under a dominant Sun. When those aspects are favorable, the native may be charismatic, outgoing, and generous, even to enemies.
That strength of character and confidence can become exaggerated, however, when those aspects are unfavorable to exhibit characteristics of vanity, arrogance, and self-importance. An inherent desire for attention will become an irritating personality of self-obsession and exhibitionism.
Being born under a dominant Sun empowers individuals to be leaders to whom others turn for advice. Many attain high positions in society. On the other hand, less favorable aspects can lead this person to become authoritarian or selfish when dealing with others.
Being born under a dominant Sun has a strong impact on one’s character and, ergo, one’s life. Astrology teaches us that those natives will stand out in a crowd, whether as a paragon of virtue or constant irritant to all she or he encounters depends of the aspects of the Sun to the other planets and elements of a natal chart.
To know your dominant planet, run your astrological birth qualities report. You might have noticed that there's a box in the "Birth qualities" under the Astro Reports page, called “Your most important planet” where you can find your dominant planet.