Sun in Sagittarius
Sun in Sagittarius means you need two things to feel like yourself: a reason and a horizon. You want to know why things are the way they are, and you need somewhere further to go, a place, a subject, a bigger version of the plan.
The Sun is in Sagittarius from about November 22 to December 21, the run-up to the December solstice. The changeover days move with the year, so if you were born on an edge, check with the sun sign calculator.
The honest answer nobody asked for
Sagittarius is mutable fire, ruled by Jupiter, the planet of more. The famous bluntness comes from a simple assumption: you'd want to know, so surely they would too. You tell a friend the haircut isn't working, then you're baffled that they're upset, because you were being kind. In your book, kindness and honesty are the same thing.
The same instinct makes you the person who asks "but why?" about every rule at a new job. It isn't rebellion. A rule with a reason, you'll follow cheerfully. A rule without one feels like a small insult to your intelligence.
Big yes, small Tuesday
Jupiter enlarges whatever it touches, and in a Sagittarius sun that includes promises. In the moment of enthusiasm you say yes to the trip, the course, the side project, the dinner for twelve. Then the ordinary Tuesday version of you has to carry it out, and the Tuesday version is less keen.
That's the honest tension. Sagittarius suns are deeply sincere at the moment of the promise, and people who've been let down once start discounting the next one. The other cost is restlessness: when life gets small and repetitive, you go looking for the exit before you've asked whether the thing is actually finished.
How your Moon and rising rein it in
The Sun gives the direction, and the Moon and rising sign decide how far you actually travel. A Sagittarius sun with a Capricorn or Virgo Moon makes fewer promises and keeps every one, and the big ideas come with a plan attached. With a Cancer or Pisces Moon, the wanderlust pulls against a strong need for home, so you leave and miss it, then come back and itch to leave again.
If your Moon is in Sagittarius as well, your mood rises and falls with whether there's something to look forward to: see Moon in Sagittarius. With Sagittarius rising, Jupiter rules your whole chart, and the first impression is open and a little too frank. With Scorpio or Capricorn rising, people meet someone guarded, and the restless optimist turns up once they know you.
Questions
Why are Sagittarius suns so blunt?
Because to them honesty is a form of respect. They assume you can handle the truth because they'd want it, and they're surprised when it stings.
Is Sagittarius compatible with Gemini?
They're opposite signs, both mutable, both curious. Gemini wants the details and Sagittarius wants the meaning, and the pairing works when both enjoy the argument more than winning it.
Do Sagittarius suns hate commitment?
They hate commitments that shrink their world. Give a Sagittarius a relationship or a job that keeps growing and they stay a long time.