Mars is the first planet in the series out from the Sun that is outside the orbit of the earth. As the first superior planet, Mars represents energy directed outward from the self into the world. It is the energy to initiate action and the ability to meet challenges and overcome obstacles. In mythology, Mars is the god of war. In the birth chart, Mars is the self assertive and aggressive urge, the sex drive and the need to achieve our desires. Positively, Mars is expressed as courage, initiative, and the will-power to pursue our goals. Negatively expressed, Mars is impatience, violence and the use of force or threats.

Mars' sign position and aspects to Mars in the chart show how we assert ourselves and express our desires. Mars is traditionally a masculine planet, and therefore represents the expression of the male ego. In a women's chart, the energy of Mars is often repressed by social and family conditioning, and indicates how she will experience the male ego through the men around her, whether positively or negatively expressed. It is, however, becoming increasingly possible for women to break away from traditional passive roles, and express their own martian drives, but this is often not completely successful until after the age of about 30.