Sun in Aries
The Sun in the sign Aries is an exaltation placement: will through direct action, initiative, and an open start. Aries is the first sign of the zodiac, fiery, cardinal, ruled by Mars. By tradition the point of the Sun's greatest exaltation (parama-uccha) is around 10° of Aries; the closer a planet stands to it, the more fully the strength of the exaltation unfolds, but the quality itself extends across the whole sign.
The Sun in Aries doesn't wait for permission. Here the will is built so that the first move is the person.
What this placement means
Aries under the rulership of Mars gives two effects. The first is starting energy: a person begins easily, tolerates a pause or a slow warm-up poorly. The second is direct will: what matters here isn't so much what others think as the plain fact of moving forward.
For the Sun in Aries it's critically important to have room for leadership and initiative. If its role as the trailblazer goes unrecognized, it loses its inner strength.
The Sun crosses a sign in about a month, and this is when the yearly highlight of the same channel of will falls: over that month, what's set by the placement in the chart is lived through. Lasting influences come through the slow planets' transits over this sign — Saturn crosses a sign in about 2.5 years, Jupiter in about a year — and through the mahadasha of Mars as the sign's ruler. A transit of Rahu over the sign lasts about a year and a half and sets a separate layer of restructuring. The houses the Sun falls into in a chart, and the planets it's linked to by aspect, specify which spheres of life sharpen during these periods.
How it manifests
In character — through initiative. A person with the Sun in Aries takes the first step: in conversation, in a project, in an argument.
In behavior — through directness. There's no long detour here: a decision is made and announced, sometimes before the other person is ready.
In self-assertion — through action, not words. The Sun in Aries proves itself by what it does, not by how it presents itself.
What to watch
The strength is the ability to start and lead. Where a first step and a will that doesn't back down are needed, the Sun in Aries works naturally.
The weak point is impatience: direct will turns into pressure on those who need time to think things over.