In a natal chart, dominant planets and signs indicate the native's broad psychological profile and his traits of characters.
A planet becomes dominant when it meets one of the following conditions:
It is posited near an angle of the natal chart (one of the angular houses, the most important ones, as we have explained in our article on houses).
It is posited in a sign of its rulership (in the case of a fast-moving planet).
It rules the Ascendant or the Sun.
It is the only planet tenanting a hemisphere (please check our article on planets' distribution).
It forms numerous aspects with other important points of the natal charts.
In general, natal charts have two or three planetary dominants, and sometimes, sub-dominants. For instance, the astrologer would talk about a Mars-Jupiter dominant with a Saturn background when Mars, Jupiter and Saturn are prominent, but Saturn is less powerfully highlighted than the former two planets.
In their common practice, astrologers very often talk about dominant signs. Like with dominant planets, a set of rules is used to identify outstanding signs:
The solar sign,
The sign where the Ascendant is posited.
The sign where the Ascendant's ruler is posited.
These signs are already prominent.
In addition, there are other factors which give special emphasis to a sign, such as:
The sign where a stellium is found,
The sign where a planet is in conjunction with an angle of the natal chart, thus naturally highlighting the sign where the conjunction is found, etc.
The "dominant" concept is highly important in astrology because it makes it simpler to determine the complex personality of the native, pending the thorough assessment which fine-tunes the traits of character. The "dominant" concept is useful because in all areas of life, the expected behaviour of a Saturnian, for instance, quite serious, rigorous, withdrawn and lone, has nothing in common with that of a Jupiterian, jovial, good-natured, powerful and benevolent. In brief, the dominant is a tool used to simplify, understand better and gain time in the process of analysing a natal chart.
For more detailed explanations of this important topic of planetary dominants, we invite you to check our Planetary Dominants: Method page. Thousands of pages of statistics about planetary dominants are available as well for free consultation at our Celebrities and Planetary Dominants page. There, you will find tens of thousands of famous peoples' planetary distribution, their natal chart and the calculation of all the planets, signs, elements, dominants etc.