How it works

Last updated: 2026-08-10 · Engine v1

trelun locks onto the exact astronomical moment you were born, then maps it through a fixed, published model into a life chart. This page explains both halves of that sentence — which half is measurement, and which half is interpretation.

Part one: the astronomy is real

A birth certificate records clock time, and clock time is a political artifact. Before anything else can happen, trelun converts it into an actual position of the earth relative to the sun.

Timezone and daylight-saving history — not today's rules, but the rules in force at that place on that date. Offsets have changed more often than most people realize.
Longitude correction — solar noon in the east of a timezone can differ from solar noon in the west by most of an hour. Your clock did not know that.
The equation of time — because earth's orbit is elliptical and its axis is tilted, true solar noon drifts against clock noon by up to about 16 minutes across the year.
Solar terms — the model's cycle boundaries are the moments the sun reaches specific ecliptic longitudes. These are computed, not chosen. They are the same events that define the solstices and equinoxes.

All of this is ordinary, verifiable astronomy. Two people born in the same city ninety minutes apart genuinely occupy different positions in that cycle, and trelun will give them different charts. If you don't know your birth time, trelun says so and widens its windows rather than pretending to precision it doesn't have.

Part two: the model is a framework, not a measurement

What trelun does with that moment is map it onto a cycle structure and read a shape from it — where the long phases begin and end, where they reinforce or work against each other, and what that implies about the rhythm of a life rather than its contents.

That structure comes from a centuries-old calendrical tradition. We reimplemented its arithmetic and deliberately dropped its vocabulary, because the vocabulary asks you to accept a worldview and the arithmetic doesn't.

We are not claiming that the sun, moon, or planets exert a force on your life.No such effect has been demonstrated, and we would be lying if we implied otherwise. What we are claiming is narrower and, we think, more interesting: that a consistent, deterministic model applied to a precisely-located birth moment produces a structure worth thinking against.

The closest honest comparison is not a horoscope. It is a career-development framework — the kind that maps you onto a small number of types and phases so you have language for a decision. Those frameworks aren't validated predictors either. They're useful because a specific, falsifiable claim you can argue with beats a vague feeling you can't.

The engine, in order

Birth moment — civil time → timezone/DST as of that date → apparent solar time
Cycle position — solar-term boundaries and long-phase transitions, versioned
Feature extraction — the shape of the curve: peak timing, volatility, late-life slope
Life Type — nearest prototype in percentile space, calibrated against a 10,000-chart distribution

Every stage is version-pinned. The same inputs and the same engine versions always produce exactly the same result — not a re-roll, not a daily variation. If your chart changes, an engine version changed, and that is recorded.

How we test whether any of it means anything

This is the part most products in this space don't publish, and it's the reason we won't call trelun scientific yet.

Every result asks you to mark the years that were genuine turning points in your life. We compare how often the model's marked years land on yours against a hypergeometric baseline— the hit rate you would expect from picking that many years at random out of your lifespan. A model that can't beat random year-picking is telling you nothing, no matter how good the sentences around it sound.

That test can fail. We built it so that it can. If it fails, that is a fact about the model and we would rather know than not.

Current status: not enough responses yet to report a result. When there are, this is where the number goes — whatever it says.

What this does not do

It does not predict events. It does not know about your job, your health, your relationships, or anything that has happened to you. It is not medical, financial, legal, or career advice, and no part of it should be used to make a decision you would not otherwise make. It is for people 18 and older.

City data

City lookup uses the full GeoNames cities15000 dataset — 34,080 populated places with verified coordinates and IANA timezones.

What we publish about you

Public share pages and images contain only a snapshot: life type, cycle, chart scores by year, and short copy. They never include your birth date, birth time, city, coordinates, or the sex used for cycle direction. Ticker codes are derived from Life Type and share id — never from your birthday. Details are in Privacy.