How it is made

Every position is computed with astronomy-engine, an open source astronomy library accurate to about one minute of arc, far finer than a chart needs.

Nadir uses the tropical zodiac and positions as seen from the centre of the Earth. Houses are Placidus; close to the poles, where Placidus is undefined, whole sign houses are used instead. The lunar node is the mean node.

The aspects shown are the five major ones: conjunction and opposition within 8 degrees, square and trine within 7, sextile within 5, and two degrees more when the Sun or the Moon is involved.

A chart needs the instant in Universal Time, so the birth time is converted with historical time zone data. Daylight saving changes from decades ago are taken into account.

The list of places holds some 70,000 towns and cities from GeoNames (CC BY 4.0) and lives on Nadir's own server. No outside service learns where you were born.

Without a birth time, Nadir leaves out the Rising sign and the houses rather than guess. If the Moon changed sign that day, it shows both readings.

The readings for the Sun, the Moon and the Rising sign in each sign are written and revised by hand. Nothing is generated while you wait.

They follow three rules: no predictions, no fear, and a question to write about at the end.

Every wheel is painted in the browser as a drawing, not a picture: each sign has its own colour, fire signs in reds, earth signs in greens, air signs in yellows and water signs in blues. On the first page the Sun, the Moon and the planets are discs on their own orbits, where they stand today.

The colours come from Hilma af Klint's paintings of 1907 and from the lapis and gold of the books of hours. The titles are set in Instrument Serif and the text in EB Garamond.

If a chart looks wrong, or you want to know more about how something is calculated, write to hola@nadirastral.com.