Planet
The Sun
The Sun is the placement almost everybody already has. Ask a stranger what their sign is and the answer is a Sun sign — the sign the Sun stood in on the morning they were born. Nothing else in a chart is that widely known, which is worth saying at the top, because the fame of one placement makes it sound like the whole map.
In matters of career it stands for identity becoming visible. That is a narrower claim than the Sun usually gets, and a more useful one: less a portrait of a private personality than of the part of a person that is meant to be seen — what shows when they are working, performing, or answering for something.
The tradition places it at home in Leo, exalted in Aries, in detriment in Aquarius, in fall in Libra.
One of the two lights
The Sun is classed among the luminaries, which puts it beside the Moon rather than among the planets. The two are read against each other constantly: a new moon is the two of them arriving at the same place in the sky and a full moon is the two of them facing off across it, and the month between is described as an inhale and an exhale.
Read its four sign placements together and they describe a gradient rather than a verdict. Leo, its home, has no embarrassment about being looked at; Aries, where the tradition exalts it, gets moving before the room has agreed. Libra and Aquarius, the two signs the classical table treats as hardest for it, are also the two most interested in somebody else — the partner, the collective. A light that has to be shared behaves differently from one that does not.
None of that is a rule about character. It is a description of how easily a particular light gets to be individual, and most charts argue with it somewhere.
Why it turns up in questions about work
Work is where being seen stops being an abstraction. A private sense of who one is has to become legible to strangers — colleagues, clients, an audience with no history of the person — and legibility is a different skill from self-knowledge. Plenty of people have the second and are still learning the first.
The tenth house says the same thing in the other coordinate: it is the public role, vocation, what a person is known for in the world. Its cusp is the midheaven, the highest-noon point of the chart — the place the Sun would stand at the top of its own arc. For once the geometry and the meaning are describing the same thing.
A luminary is not a specialist, and reading the Sun at work alone would be a thin use of it. Visibility is simply where its behaviour is easiest to point at.
Sun sign, and the trouble with it
A Sun sign is real information at a coarse resolution — everyone born inside the same few weeks carries it — which is why it can feel accurate and thin in the same breath.
What separates two people who share one is usually the house. The same Sun sign lived out in the sixth, among routine and service and the apprenticeship layer of work, and in the tenth, in front of the public, produces two people who would not recognise each other's weeks.
That is the part a general page cannot supply. It can say what the Sun is for. It cannot say where a particular one landed, and the house depends on the hour of birth rather than the date.