Aquarius
Aquarius is fixed air, the sign of deep winter in the northern hemisphere, when the cold is established and the light is still a theory of return. The image is the water-bearer. The water is often drawn as waves poured out of a jar, and many traditional authors treat the sign as air regardless of the water in the picture: a distribution, a current shared across a group. Fixed signs hold. Air signs hold an idea or a bond among many. Aquarius holds a principle in common.
The weather is cool, systematic, and concerned with the circle rather than the single heart. It wants a rule that applies beyond one person's preference, a friendship of shared aim, and a future that can be described. Classical air is hot and moist in the temperament lists, and Saturn's cold rulership complicates the sign: the air of Aquarius is often pictured as dry and bright, a high winter sky. The practical result in a chart is detachment that can be a kindness. A person can see the pattern because they are not only inside their own weather.
Saturn is the traditional ruler, and Saturn also rules Capricorn. In Aquarius, Saturn is in his air domicile: limit, time, and structure expressed as a system, a law for the group, a friendship with duties. Modern astrology assigns Aquarius to Uranus. That is a later convention, useful when you are reading in the modern dialect, and it is not the medieval or Hellenistic domicile. This library leads with Saturn and names Uranus so both languages are available. The Sun is in detriment in Aquarius, opposite his domicile in Leo. A single radiant center fits this weather poorly. The sign keeps asking how the light serves the circle. The Sun can still shine here. He shines as a contributor to a pattern, and he may resent the request.
There is no classical exaltation of the seven planets assigned to a degree of Aquarius in the standard scheme. The dignity story is Saturn's domicile and the Sun's detriment.
The natural house is the eleventh: friends, allies, the gifts of the ruler, and hopes. Traditional texts are more political than the modern word "community" suggests. The eleventh is the place of supporters and of good fortune that comes through others. A planet in the sign of Aquarius brings a fixed-air, saturnine style to whatever house it occupies. The house says where the principle is applied.
Sun in Aquarius makes the conscious will idealistic and sometimes stubborn about the ideal. The person often knows themselves through the group they refuse and the group they choose. Moon in Aquarius feels at a slight distance, and the distance can be how they stay kind. Saturn in Aquarius is the traditional ruler at home. The Ascendant in Aquarius makes a first impression unusual, principled, or hard to warm at once, and it needs a birth time.
Aquarius squares Taurus and Scorpio, and it opposes Leo. The opposition is the pair of the circle and the heart. Trines run to Gemini and Libra. Air recognizes air. The gift is a view wide enough to be fair. The risk is a principle that never comes down to one person's actual Tuesday.
In a reading, ask which rule is being kept, and for whom. Aquarius's gift is a loyalty to something larger than appetite. Its risk is a system that forgets the bodies inside it. For the traditional ruler, read Saturn. For the modern dialect, read Uranus. For the opposite fire, read Leo. For allies and hopes, read the eleventh house.