The major asteroids in a chart
- Beyond the ten planets, modern charts often add five small bodies: Chiron plus Ceres, Pallas, Juno and Vesta.
- Ceres, Pallas, Juno and Vesta are the four largest main-belt asteroids; Ceres is now classed a dwarf planet.
- Chiron orbits between Saturn and Uranus and is a 'centaur', not a main-belt asteroid.
Five small bodies used in practice
| Body | Glyph | Swiss Eph. no. | Astronomical class | Common astrological theme |
|---|---|---|---|---|
| Chiron | ⚷ | 15 | Centaur (Saturn–Uranus) | The wound that teaches; healing |
| Ceres | ⚳ | 17 (sweph) | Dwarf planet, largest asteroid | Nurture, food, cycles of loss and return |
| Pallas | ⚴ | 18 (sweph) | Main-belt asteroid | Wisdom, pattern, creative strategy |
| Juno | ⚵ | 19 (sweph) | Main-belt asteroid | Commitment, partnership, fairness |
| Vesta | ⚶ | 20 (sweph) | Main-belt asteroid | Focus, devotion, the sacred flame |
The four 'great asteroids'
Ceres, Pallas, Juno and Vesta were the first four asteroids discovered (1801–1807) and are the largest in the main belt between Mars and Jupiter. Ceres, the biggest, was reclassified as a dwarf planet by the IAU in 2006 — the same decision that reclassified Pluto.
Astrologers added them to charts in the 20th century, often read as a quartet describing nurture (Ceres), wisdom (Pallas), commitment (Juno) and devotion (Vesta). They are optional: many traditional readings use only the ten planets.
Chiron is different
Chiron is not a main-belt asteroid. Discovered in 1977, it orbits in an unstable path between Saturn and Uranus and belongs to a class called centaurs. Its orbit takes roughly 50 years.
Because its positions are harder to model, astro.otldr.com computes asteroid positions with the Swiss Ephemeris (via WebAssembly) rather than the general planetary engine used for the main planets.