1. Software calculates
Astrologican uses Astronomy Engine 2.1.19, distributed under the MIT license. For a specified UTC time, it returns apparent geocentric longitude and latitude in the true ecliptic of date. Light-time and aberration corrections are enabled.
Tropical signs divide normalized longitude into twelve half-open 30° bands, beginning at the true equinox of date. That zodiac mapping is a declared astrological convention, not an astronomical discovery.
2. Event times use repeatable numerical searches
- Primary Moon phases are the geocentric Sun–Moon longitude differences of 0°, 90°, 180°, and 270°.
- Ingresses are crossings of the declared 30° tropical sign boundaries, with direct or retrograde direction retained.
- Stations are zero crossings in sampled apparent ecliptic-longitude speed. “Stationary” on Today’s sky uses the separately declared 0.005°/day display threshold.
- Exact major aspects are roots at 0°, 60°, 90°, 120°, and 180° angular separation. The wider aspect orbs on Today’s sky are editorial conventions and are not used to find exact annual events.
The numerical root search terminates at a one-second interval. That is an algorithmic stopping rule, not a promise that different ephemerides agree to one second. Pages show the full calculated UTC value so a particular result can be reproduced exactly.
3. The public calendar has an explicit scope
Annual calendars include all configured body ingresses, stations for Mercury through Pluto, and all four primary Moon phases. Exact aspects use the Sun and Mercury through Pluto, but deliberately omit the Moon. Including lunar exact aspects would add more than nine hundred fast events per year and obscure the slower annual chronology.
This scope is listed with each year’s data and repeated on calendar pages. The result is not described as every possible ephemeris event.
4. Selected results are compared with independent sources
Reference results were prepared offline from the NASA/JPLHorizons API and the U.S. Naval ObservatoryAstronomical Applications API. They were prepared independently of Astronomy Engine.
- Twenty reference 2026–2027 geocentric positions—two samples for every configured body, including Pluto—are checked within 0.02° circular longitude and latitude tolerances; the observed maximum differences are 0.0033655° and 0.0026851° respectively.
- All 99 primary Moon phases across the two years are checked in order and within five minutes of the minute-resolution USNO source; the observed maximum difference is 79.496 seconds.
- One Sun 0° ingress in each year and a 2026 Mercury direct-to-retrograde station bracket provide independent boundary and motion checks.
The comparison set is deliberately limited: it is not an independent dense ephemeris for every event. Exact aspect angles and orbs remain declared project conventions, tested against independently checked positions rather than presented as independently published event lists.
5. UTC and future-time limits remain visible
Input and display use UTC. The engine setting records its UT1/UTC approximation. Horizons also warns that future UTC conversion uses the last known leap second until a later one is determined. Source data is updated only after its evidence is checked; it is never replaced automatically when someone opens or publishes the site.
Astronomy tables do not calculate local rise/set visibility, weather, topocentric position, or a visitor’s timezone. The separate Big Three tool resolves a visitor-entered IANA timezone locally and exposes Rising only because the calculation has passed eight independent test cases.
6. Calculated data is checked before publication
The astronomy reference time is 2026-10-19 12:00:00.000 UTC, and the public calendar years cover 2026, 2027, 2028, 2029, 2030, 2031, 2032, 2033, 2034, and 2035. Events from the preceding year are also kept so horoscope periods that cross New Year can be checked; that year is not presented as an additional calendar. The data does not use a changing “generated at” time. Before publication, the calculations are repeated and compared exactly with the stored values. Any difference stops publication, and this check makes no network request.
Astrology and numerology content remains reflective editorial material, not established scientific prediction. Calculated positions describe the implemented mathematical convention; they do not validate astrological interpretation.
7. Horoscope drafting cannot alter calculated facts
Horoscope periods are exact UTC daily, ISO-weekly, or monthly intervals. A versioned astronomy fact set selects annual events inside the interval and, where available, at most the nearest event before and after it. Today’s sky view is not used as a horoscope fact. Every record keeps a unique fact ID, source, checksum, timestamp, and explicit before,during, or after relationship. A neighboring event cannot be described as occurring inside the requested period.
Horoscope writing uses that dated sky context; it does not calculate or alter positions. The prose treats astrology as a language for reflection, not as proof that an event must happen. Every edition contains all twelve signs, and the exact sky events remain visible separately from the interpretation.
Editions are prepared as complete twelve-sign sets and carry their actual UTC day, week, month, or year. Reading a page does not generate or change its horoscope.
8. Personal tools calculate locally and expose uncertainty
The Big Three tool never submits birth input. Browser IANA timezone data resolves a local wall time into UTC; repeated times require an explicit earlier/later choice, skipped times are rejected, and unknown birth time produces a full-local-date Sun/Moon range with Rising unavailable. Rising is the eastern geometric-horizon/true-ecliptic intersection, with no atmospheric refraction and east-positive longitude.
The Life Path tool reduces month, day, and all four displayed year digits separately, preserves 11, 22, or 33 at component and final stages, and displays every arithmetic step. The number meanings are separately labeled traditional reflections; they do not change the arithmetic. This is a declared numerology convention, not a scientific measurement or prediction.
The affirmation practice follows a fixed, curated sequence for the focus a visitor chooses. It does not infer a profile, draw a random prediction, or claim an outcome. Calculators and the picker run on the visitor’s device. The optional place list loads only when requested, and every tool selection remains local. See the privacy page for the detailed storage and request behavior.
9. Full charts declare their geometry and time model
The full birth chart uses ten bodies from the Sun through Pluto, an instantaneous osculating North Node, the Ascendant, Midheaven and twelve house cusps. Planetary positions are tropical and geocentric. The node is a specified numerical model, so it should not be compared with a mean node as if the two were the same quantity.
Full natal charts, chart comparisons, the date explorer, personal transits and solar returns use the project’s pinned offline time-scale module. Within the snapshot’s coverage it uses leap-second and Earth-rotation data to distinguish UTC, UT1 and TT. Outside that coverage it reports an approximation. The annual calendars, lunar phase calculator and observing searches use Astronomy Engine’s standard time model. A displayed second is not a universal one-second accuracy claim.
Chart dates cover 1900–2099. Placidus uses project-authored spherical geometry and is available only below 66° north or south. Whole Sign must be selected explicitly; it does not silently replace Placidus. Geographic poles are unsupported. Major chart aspects use 0°, 60°, 90°, 120° and 180°, with respective orbs of 8°, 4°, 6°, 6° and 8°; an aspect involving the node is capped at 3°. Numerical guard bands flag nearby classification boundaries without changing the calculated position or claiming a universal error bound.
10. Comparisons preserve uncertainty and repeated contacts
The birth-time interval checks an explicit two-minute grid, including both endpoints. Gradual sign changes detected between adjacent samples are refined to a one-second bracket; large jumps remain unresolved sampling intervals. House stability describes the sampled times. A finite grid cannot prove that every shorter change was found. It is not birth-time rectification and assigns no probability to a possible minute. The two endpoints are resolved independently when clocks repeat; a local calendar date can be shorter or longer than 24 hours.
Personal transits compare moving Sun, Mercury, Venus, Mars and the outer planets with all ten natal planets, the true North Node, Ascendant and Midheaven. They retain separate direct and retrograde passes, search major angles with six-hour brackets and refine detected crossings to one second. The 1° orb windows are clipped to the requested interval and identify open ends. Exact tangencies or short entries and exits between samples are not guaranteed to be found.
Synastry keeps both charts, cross-chart aspects and the two directions of house overlays separate. It supplies no compatibility percentage. A solar return finds the matching apparent solar longitude near the requested birthday. The return location changes its angles and houses, while the original birth record and return instant stay separate.
11. Observing geometry and exports have separate limits
The local sky uses an observer at the entered coordinates and sea-level elevation, with standard atmospheric refraction. Altitude and rise/set calculations do not model local terrain, buildings, weather, visibility to the naked eye or the equipment needed to observe a body.
The eclipse tool distinguishes local solar contacts from global lunar phases. Lunar contact altitudes and any Moonrise or Moonset during the eclipse describe the observer’s horizon opportunity. Solar obscuration is the covered area of the Sun’s disc; lunar umbral obscuration describes the Moon’s area inside Earth’s umbra. These are different quantities. Never observe the Sun without correctly rated solar protection.
Two rounded central-line points from the NASA 2024 solar eclipse tableand the global peak of the NASA March 2026 lunar eclipse referenceprovide additional independent checks. This limited fixture set does not validate every observer, every contact or every future eclipse.
Calendar downloads are user-requested ICS snapshots. UTC event instants let a calendar application choose its own display time zone. Annual ingress, station and aspect exports reuse the published calendar datasets; primary Moon phases can be calculated for any supported year. No calendar account is connected and no hidden birth-input payload is placed in the file. A personal-transit export still contains personal calculated results and should be shared only when intended.