The Sun is the most well known of the celestial bodies. In astrology, it, along with the Moon, are given special status among the objects of the sky; they are called Luminaries, because one provides light by day, the other by night.
This special term was not just an empty title. The ancients regarded them, and the changes they made, as the most powerful astrological influences.
The Sun represents the heart in the body, and also the heart's desire. In fact, that's why Sun Signs work; the sign that the Sun is in at birth shows the way you go about fulfilling your deepest desires. The Sun is about what you do and the actions you typically take. It can be about your ambition, but other factors contribute to this complex facet of the personality.
It takes a little longer to pass through some signs than it does through others, but the rule of thumb is that the Sun takes approximately thirty days to pass through each sign of the Zodiac.
Entire methods of analysis and prediction changed depending on whether one was born in the daytime or at night. Days used to be counted from sunrise until the next sunrise; starting the "day" at midnight is a fairly recent invention that would have boggled the mind of those born in the classical era.
Even today, sunrise or sunset marks the beginning of the day for some calendars. The Sun is also the marker of the year; the seasons are defined by the position the Sun holds on the eastern horizon at sunrise.
First of all, the Signs of the Zodiac fall upon the Sun's apparent path through the sky, not on the constellations they are the images or representatives of. This is why they are called "Sun Signs" in modern popular astrology books. Each of the astrological planets has certain "dignities" or places within the Zodiac where they seem to outperform the rest. These are the places where the greatest affinity is found.
The Sun's sign is Leo, meaning that the sign Leo is the domicile, or house of the Sun. This is the sign in which the Sun expresses itself best.
The opposite sign is Aquarius; this is the place where it is said to be in its detriment; it's the place furthest from the sign it owns, and does not express its natural traits well. This is much like a person far away from home and unfamiliar with the surroundings and the people; planets in their detriment have a hard time being themselves.
Aries is the Sun's place of exaltation; this means that its attributes are appreciated in this sign, and people born in Aries are generally looked up to and seen as leaders when they express the Solar side of their natures.
The opposite sign is called a planets "fall", and this means exactly the opposite; people are usually criticized or looked down on when they exhibit their Solar characteristics. Libra is the opposite sign from Aries, and therefore the Sun's fall. People born in Libra tend to avoid exhibiting the kind of self-assured Solar nature, probably because they get "bad press" or are accused of being selfish and egotistical when they do.
The Sun is said to be a benefic planet, meaning that it generally favorable. This is more of a cultural designation, because in India, the Sun is considered hot-tempered and cruel.
Obviously, an ancient astrologer living in Oslo would welcome the Sun's rising as relief from the cold in winter, while one in Mumbai might worry about whether or not his crops would burn.
So what are some of the natural characteristics associated with the Sun?
The Sun is considered to be extroverted, warm, friendly, protective, proud, self-confident and generous. People with the Sun dominant in their birth horoscopes (people born at sunrise, noon or in the sign Leo) generally exhibit these characteristics.
At the same time, the Sun can be overbearing, egotistical, domineering, selfish, arrogant, entitled and bossy. Usually the negative characteristics are the result of the position the Sun's sign holds in the complete horoscope, or the way it is configured with other planets.
The Sun represents relationships with men in a woman's complete chart, and those who have the Sun dominant in some way tend to be more aggressive in business, and quicker to grasp opportunities than others.
The Sun is considered to be male in the current astrological tradition, and the symbol of truth. There is so much more to understanding the Sun than this, but you can learn a good deal about how it relates to you and your relationships by reading the various articles about your Sun Sign.