Glossary

Every term, in a sentence or two.

Any word with a dotted underline on this site opens its definition here. Glyphs are the standard ones used in Western astrology.

The chart

Rising sign (Ascendant)AC: The sign on the eastern horizon at the moment you were born. It is the part of the chart that moves fastest, so it depends most on the birth time.
MidheavenMC: The highest point of the chart, the 10th-house cusp. Like the ascendant, it shifts quickly with the birth time.
Descendant and ICDC · IC: The points opposite the Ascendant (7th-house cusp) and the Midheaven (4th-house cusp). Together the four are called the angles.
Houses and house cusps: The chart is split into twelve houses, each tied to an area of life. Where each house begins (its cusp) depends on the birth time and place.
Placidus: The house system we use to draw the twelve house cusps. It is the most common one in Western astrology.
Aspect (conjunct, square, opposite): The angle between two points of the chart: 0° is conjunct, 90° is square, 180° is opposite. We only score these three against the angles.
Orb: How many degrees a contact is from being precise. The smaller the orb, the tighter the contact.

Rectification: Working backwards from dated life events to the birth time whose chart fits them best.
Candidate time: One of the possible birth times we test, every 5 minutes across your range.
Transit: Where a planet actually was in the sky on the date of an event.
Progressed Moon: The birth chart moved forward one day for each year of life; the Moon is the fastest part of it.
Solar arc: Every point of the chart moved forward by the Sun's yearly motion, about 1° a year.
Evidence strength: A rough guide to how much your events can tell apart: dated to the day counts most, then month, then year.
Held-back check: Before scoring, we set some of your events aside. If the window we pick also fits those, the result is less likely to be chance.

Fit (0–1): How well one event lines up with the chart at that time, from 0 (not at all) to 1 (very well).
Window: The short stretch of candidate times that fits your events best. We give a window, not a single minute.
Runner-up: The second-best stretch of candidate times. The bigger the gap to it, the more confidence.
Confidence: How clearly your events separate the window from the other candidates: Low, Moderate or High, with the reasons shown.