Geocentric Tropical
Meaning
Earth-centered body positions labeled against the tropical zodiac, where 0 Aries is tied to the equinox.
Use
Standard Western-style body positions and Date Panel cycles.
Geocentric, Heliocentric, Tropical, And Sidereal
TimeMatrix keeps observer frame and zodiac frame separate because they answer different questions. Geo and Helio tell the app where to measure from. Tropical and Sidereal tell the app how to label the resulting longitude. Together, these controls support geocentric and heliocentric astrology research in both tropical and sidereal astrology systems without treating the four combinations as interchangeable.
Core Idea
Two Switches, Not One
Heliocentric is not a complete zodiac system by itself. It means the Sun is the measuring origin. After a Sun-centered longitude is calculated, the app still needs a zodiac frame so it can display a sign, degree, glyph, and boundary cycle.
Accuracy And Scope
Calculated Astronomy Versus Interpretation
Geocentric and heliocentric describe the calculation origin. Tropical longitudes use the equinox-based ecliptic reference; sidereal signs use a selected ayanamsha convention. Sign names and their interpretation are astrological labels layered onto calculated longitude. See the U.S. Naval Observatory coordinate glossary and the Swiss Ephemeris sidereal reference.
Settings
What Each Choice Controls
| Setting | Choices | Answers | Does Not Answer |
|---|---|---|---|
| Observer Frame | Geocentric or Heliocentric | Where the position is measured from. | It does not decide whether signs are Tropical or Sidereal. |
| Zodiac Frame | Tropical or Sidereal | Which zodiac reference is used for signs and degrees. | It does not decide whether the observer is Earth or Sun. |
Combinations
Why All Four Modes Exist
Geocentric Sidereal
Meaning
Earth-centered body positions labeled against a selected sidereal ayanamsa.
Use
Vedic, Western sidereal, nakshatra, and ayanamsa comparison research.
Heliocentric Tropical
Meaning
Sun-centered body positions labeled against the tropical zodiac.
Use
Sun-centered planetary cycles where the tropical sign boundaries are still the reference labels.
Heliocentric Sidereal
Meaning
Sun-centered body positions labeled against a selected sidereal ayanamsa.
Use
Sun-centered planetary cycles compared through Lahiri, Fagan-Bradley, Raman, KP, and the other supported sidereal frames.
Sidereal Helio
Why There Are Multiple Heliocentric Sidereal Views
The Sun-centered physical position is the same starting point, but each sidereal ayanamsa defines 0 Aries with a different date-specific offset. That means Lahiri Helio, Fagan-Bradley Helio, Raman Helio, and the other supported sidereal Helio views can show different signs, degrees, nakshatras, and boundary dates from the same heliocentric base position.
Retrograde Shade
Why Helio Singles Hide That Setting
Retrograde shading on Zodiac Singles is a geocentric apparent-motion overlay. When a Singles panel uses Heliocentric observer mode, that Retrograde Shade setting is hidden and no Singles retrograde shading is drawn. Zodiac Pair degree rows still keep motion-state axis band colors, and Pair glyph rows still keep contraction shade, because folded separation can expand, contract, and turn even when the body longitudes are measured from the Sun. Supported geocentric Singles also provide a Shade Opacity control (88% by default in Dark mode and 50% in Light mode); Pair glyph contraction shade reuses that saved visual opacity without exposing a separate Pair Retrograde Shade control.
TimeMatrix Coverage
What Is Loaded Now
| Geocentric | Tropical and supported Sidereal rows cover the production Date Panel body set from 1900-01-01 through the2050-01-01 endpoint. |
|---|---|
| Heliocentric | Tropical and supported Sidereal rows are loaded in the separate heliocentric cache for Earth, Mercury through Pluto, and the curated minor-body set over the same production range. |
| Helio Exclusions | Sun, Moon, North Node (True), and South Node (True) remain geocentric-only in the product. The Sun is the heliocentric origin; a heliocentric Moon track would mostly follow Earth's solar orbit rather than provide an independent planetary cycle; and the true nodes are Earth-Moon orbital points. |
| Sidereal Systems | TimeMatrix supports the same production sidereal systems listed in the Ayanamsa Docs. |
Plain English
The Short Version
Geo versus Helio changes the measuring origin. Tropical versus Sidereal changes the zodiac label system. TimeMatrix needs both choices because a user may want Earth-centered or Sun-centered positions, and may also want those positions labeled through Tropical signs or through a selected Sidereal ayanamsa.