About our method

Your lines

Astrocartography takes the sky at the moment you were born and projects it onto the world map. For the Sun, the Moon and eight planets (Mercury to Pluto) we find the places on Earth where that body was rising (ASC), setting (DSC), at its highest point (MC) or at its lowest point (IC). That gives 40 lines: ten bodies with four angles each.

• Positions: from DE440, the planetary ephemeris of NASA’s Jet Propulsion Laboratory, read with Skyfield, an open-source astronomy library.
• Your birth time: we convert the local time at your birth place into universal time using the historic time zone rules for that place and date (the IANA time zone database).
• Unknown birth time: we use noon and mark the lines as approximate. Lines move about one degree of longitude, roughly 80 to 110 km, for every four minutes of birth time.

How we check the calculation

Automated tests compare every one of the 40 lines with a second calculation, the observer model built into the astronomy library, which reaches the answer by a different route. The Moon moves so fast and sits so close to Earth that the two methods can differ by about a degree because of parallax; we keep that tolerance in the open rather than hide it.

Your places

• We look at national capitals and cities of 300,000 people or more (1,553 places, from the public-domain Natural Earth data set).
• A line counts fully within 150 km of a place and fades in a straight line to nothing at 700 km.
• A place is scored by its single best supportive line. A demanding line (Mars, Saturn, Pluto or Neptune) within 300 km lowers its score by half of that line’s weight, and is always shown. Demanding does not mean bad: it may ask more patience or effort.
• When scores tie, well-known cities come first, then the closest one.
• Places are at least 150 km apart, and no more than four of your top 20 share the same line. Your free top 3 come from three different lines.

We tested adding up every line near a city and rejected it: it ranked remote towns brushed by distant lines above cities sitting on a line. Choosing the single best line keeps each pick explainable: this city is 26 km from your Venus MC line.

Your birth place

The place you type is matched against GeoNames, a public list of 34,195 towns of 15,000 people or more, stored on our own server. Born in a village? Choose the nearest town: the difference is small on a world map.

How your report is written

• What each line means comes from a library of 40 line meanings, drafted with AI and then edited and approved by the founder. A report only uses meanings that have been approved.
• The notes about your own places are written with an AI model (Claude, by Anthropic) from your calculated lines and places only. It never receives your birth date, time or place.
• Automatic checks compare the text with the calculation (every city, line and distance must match) and reject predictions, guarantees and health, money or legal advice.

What astrocartography is, and is not

Astrocartography was popularised by the astrologer Jim Lewis in the 1970s. It is an astrological tradition: there is no scientific evidence that it predicts events, and we do not claim that it does. We offer it for insight and reflection: a way to think about where you have felt at home, where you would like to travel, and what themes you might want more of. Work, cost of living, visas and the people you love matter far more.

Sources and credits

• Planetary positions: NASA JPL DE440 ephemeris; Skyfield (MIT licence).
• Land outlines and cities: Natural Earth (public domain).
• Birth-place data: GeoNames, geonames.org (CC BY 4.0).
• Fonts: Gloock and Work Sans (SIL Open Font License).

For insight and reflection. Astrocartography does not predict events.