What's actually happening
A New Moon occurs when the Moon and Sun share the same zodiacal longitude. The Moon's lit face is turned away from Earth, leaving the sky on her side dark. Astronomically it is a conjunction; symbolically it is the seed point of the lunar month.
For a New Moon in Sagittarius, both lights are in Sagittarius at the exact conjunction. The moment is expansive, directional, and oriented toward the far horizon rather than the immediate ground.
What the tradition makes of it
Sagittarius is a mutable fire sign, ruled by Jupiter. Mutable signs adapt; fire signs ignite. A New Moon in Sagittarius is a beginning organized around reach — the willingness to commit to something larger than what is already known.
The tradition reads this phase as favorable for new courses of study, philosophical commitments, travel, and the kinds of intentions that require genuine risk: not the risk of losing something, but the risk of expanding beyond the currently familiar self.
How to actually use it
Choose one commitment that requires you to go beyond the already-known: a course of study, a genuine question about what you believe, a physical or intellectual journey. The Sagittarius New Moon rewards the beginning that has some real stretch in it.
The shadow is the big vision that replaces action. What it asks for is not a declaration of where you want to go but a first real step in that direction.
When in doubt
Ask what you are genuinely willing to learn — including what you might learn about what you already believe.