What it is
A birth chart (also called a natal chart) is a snapshot of the sky at the exact moment and place of your birth. It is drawn as a circle: the twelve zodiac signs run around the outside, and the Sun, Moon and planets are placed inside according to where they appeared from your birthplace.
Three pieces of information build it: your birth date, your birth time and your birth location. The date fixes the slow-moving planets, the time and place fix the fast-moving ones — especially the Moon and the horizon line that gives you a Rising sign and houses.
Astrologers read the chart as a symbolic language. A planet in a sign describes a quality; a planet in a house describes an area of life; the angles between planets describe how those qualities meet. None of this is cause and effect. It is a set of images to think with.
Why it matters for daily reflection
Think of your birth chart as a fixed reference point. The sky keeps moving, but the chart stays where it was. That makes it useful for noticing: when today's Moon passes over a sensitive spot in your chart, you have a name for the mood, and a reason to pay attention rather than to predict.
Over weeks, the chart becomes a vocabulary. "Mars in the third house" stops being jargon and becomes shorthand for how you tend to argue or rush a conversation. The chart does not tell you who you are. It gives you a place to look.
In Lunara
Your birth chart is the first step in Lunara's daily loop. The free tier includes a basic natal chart, and every day's personal Signal is drawn from how today's Moon meets it. If your birth time is unknown, Lunara still builds the chart but does not show a Rising sign or houses — it never guesses a time.