Method

What Orrery computes, and what it doesn’t

Astrology is not one method. Every choice below has several defensible answers, and different answers produce different days. Orrery picked one of each and holds to it. This page says which, so you can check the arithmetic rather than take it on faith.

Where the positions come from

NASA/JPL’s DE440s ephemeris, read with Skyfield — the same planetary data used for spacecraft navigation. Orrery runs this through the Kairos engine, using apparent geocentric positions against the ecliptic of date. The astronomy is not the part anyone should doubt.

The choices

• Tropical zodiac, not sidereal.
• The five Ptolemaic aspects — conjunction, sextile, square, trine, opposition. No quincunxes, no harmonics.
• Void-of-course, modern definition: from the Moon’s last exact aspect to any body from the Sun through Pluto, until it changes sign. If it perfects no aspect at all in a sign, that whole transit is void. The traditional definition counts only the seven classical planets and would give you different days.
• Mercury retrograde, station to station. No shadow periods.
• No houses — not yet. See below.

These are fixed, not preferences, and Orrery won’t offer them as settings. A computed condition here can be checked against any published almanac — that’s the whole point of it. If the method were a dial, two people would get contradictory answers and both would be “right,” which is a horoscope generator with extra steps.

Why there are no houses yet

Orrery doesn’t compute houses today. Not because they can’t be — they’re ordinary maths, and a house computed here could be checked against any published chart, same as everything else on this page.

The reason is the birth time. The Ascendant moves a full circle every day — about one degree every four minutes. Without an exact birth time, the houses of your chart aren’t approximate, they’re every sign; and most people don’t know their birth time. Everything else Orrery computes degrades quietly when a detail is missing. Houses of a birth chart can’t.

Houses cast for the moment you’re deciding, rather than for your birth, don’t have that problem — they need no birth data at all. Whether those belong here is an open question, not a settled one.

What your birth details are for

In the app, honestly: nothing yet. Signup asks for a birth date (and a birth time if you know it); they are stored for a planned personal layer and nothing in the app reads them today — see Privacy, which says the same.

The one place birth details are computed with right now is the concierge Founding Moment Charter, and there the rules are strict:

• Birth date — fixes the one natal planet the calculation targets to within a fraction of a degree.
• Birth city or region — used for exactly one thing: resolving your birth timezone, which decides what instant you were actually born at. Someone born at 1am on 17 April in Tokyo was born on the 16th in universal time; without the zone, the calculation would read the wrong day’s sky. Coordinates are never looked up — not needed, not wanted.
• Birth time, if you know it — sharpens the result to an instant. If you don’t know it, the calculation covers your entire birth day — and if the answer would change anywhere in that day, it refuses to answer rather than guess.

Charter birth details never enter Orrery’s database: they stay in your browser until you choose to send them, are handled privately, and are deleted within 30 days of delivery.

And the honest part

The positions are real; the rules that turn them into a score are astrological, and there is no evidence the Moon has any bearing on whether your pitch lands. Orrery is precise about what it computes. That is a different claim from the computation meaning anything — see Terms.