How Mazarion calculates your chart

Planetary positions: Astronomy Engine

Mazarion calculates the Sun, Moon, and Mercury through Pluto using Astronomy Engine. These calculations run locally in your browser or app. We obtain apparent geocentric positions—positions viewed from the Earth’s center—and convert them into ecliptic longitude to place each body in the zodiac.

The Astronomy Engine documentation describes testing against reference systems including NASA/JPL Horizons. This is a property of the underlying library’s validation; it is not a claim that every part of Mazarion’s chart has been independently validated against NASA data.

We do not request a live NASA feed to generate your chart. JPL Horizons is a reference system for solar-system positions. Its use in library testing does not validate astrological interpretations or imply NASA endorsement.

Tropical zodiac, Equal Houses

We divide the full 360° of ecliptic longitude into twelve 30° tropical signs. The zodiac begins at the March equinox point. These coordinate divisions are distinct from the astronomical constellations with the same names.

When birth time is known, we calculate the Ascendant from time and location. Each Equal House then spans 30°, starting at that Ascendant degree. For example, an Ascendant at 12° Taurus gives a first-house cusp at 12° Taurus and a second-house cusp at 12° Gemini.

The Midheaven is calculated separately. In Equal Houses it need not coincide with the tenth-house cusp. A chart using Whole Sign, Placidus, or Porphyry houses may therefore show different house placements.

Aspects and retrograde motion

We compare planetary longitudes to find angular relationships. A relationship is included when it falls within the configured allowance, or orb, of an aspect’s exact angle.

Retrograde labels describe apparent backward movement in zodiac longitude from the Earth’s perspective. They do not mean that a planet physically reverses its orbit around the Sun.

What remains approximate

The North Node uses a simplified mean-node formula. Chiron uses a simplified mean-longitude approximation rather than a dedicated ephemeris. Their displayed degrees should not be treated as precision positions, and aspects involving them inherit that limitation.

The Ascendant and Midheaven use our own sidereal-time and obliquity formulas; they are not supplied by Astronomy Engine. The library’s accuracy statements should not be extended to those angles, the house system, or the chart as a whole.

Birth time and the historical timezone can affect the result more than rounding. If time is unknown, we use noon for planetary estimates and hide time-dependent chart features. Read why birth time matters before interpreting close boundaries.

The reading is a separate layer

Signs, houses, and aspects become prompts through astrological interpretations. Accurate astronomy does not establish that those meanings predict personality or events. Mazarion presents them alongside separate self-reflection frameworks, with room for you to accept, question, or reject a theme.

When comparing two apps, compare their inputs and calculation choices first. Similar source astronomy does not imply identical house placements, aspect lists, or written readings.