Notes
Common questions about astrology and the astronomy behind it, written by hand.
Does astrology work? What accuracy can and cannot mean
Three different things get called accuracy in a horoscope. Only one of them carries an error bar, and the Forer effect accounts for much of the rest.
4 min read
How to read a birth chart, beginning with three positions
A birth chart is the sky over one place at one instant. What the wheel shows, how a position written 23°14′ is read, and what houses and aspects are for.
4 min read
Sun sign traits: what a sun sign actually describes
A sun sign is a twelfth of the solar year measured from the equinox, and the twelve descriptions are four elements crossed with three modalities.
4 min read
Zodiac sign compatibility: what the grid actually measures
Where the compatibility grid comes from, why comparing two sun signs is the thinnest version of it, and what this site does not compute.
4 min read
Birthday to zodiac sign: the twelve ranges, and the seventeen dates a table cannot settle
This year's twelve date ranges, the seventeen calendar dates that change sign between 1930 and 2030, and why those dates need the year of birth before the hour.
4 min read
New moon and full moon: what a lunar phase actually is
A phase is an angle: 0° at new moon, 180° at full. Where the synodic month of 29.53 days comes from, the eight names, and what the tradition reads into them.
4 min read
What a rising sign is, and why it needs a birth time and place
The ascendant is the degree of the ecliptic rising in the east at the moment of birth, and it moves one degree every four minutes.
4 min read
Sun, moon and rising sign: what each of the three describes
What the sun, moon and rising sign each describe, why they disagree, and why that disagreement is the ordinary case.
4 min read
Zodiac dates are not fixed: why the same birthday changes sign
Seventeen calendar dates change sign between 1930 and 2030, because the tropical year runs about 365.2422 days.
4 min read
How a horoscope is computed — the astronomy, and where the writing comes from
What an ephemeris computes, how accurate it is, and which half of a horoscope is written rather than measured.
4 min read
Moon sign: what it is and how to find it
What a moon sign is, why the hour of birth usually settles it, and how it differs from the moon phase.
4 min read
Unknown birth time: what a chart can still say
Which placements survive without a birth time, where the hour may still be recorded, and what a guess costs.
5 min read