For a long time, most of my work around astronomical and astrological software revolved around wrappers and bindings — especially around Swiss Ephemeris integrations.
Over the past few months, I decided to move deeper into the actual engine layer itself.
Instead of only building language bindings, I started building a fully open, extensible, MIT-licensed ephemeris engine in C designed for:
- astronomy
- astrology
- astronomical almanac systems
- planetary calculations
- eclipse computations
- sidereal and coordinate systems
That project became:
JPL Moshier Ephemeris
An independent native ephemeris engine written in C.
Why Build Another Ephemeris Engine?
Most existing ephemeris systems are:
- closed-source or partially restricted
- GPL/commercial licensed
- difficult to extend cleanly
- tightly coupled to legacy APIs
- not designed for modern multi-language interoperability
I wanted a foundation that was:
- fully MIT licensed
- extensible
- embeddable
- project-owned
- cross-platform
- suitable for modern bindings and runtimes
The goal was not just to wrap existing systems, but to build an actual reusable engine layer.
Core Architecture
The engine supports multiple calculation backends and analytical models.
Supported Systems
- JPL/CALCEPH kernel-backed calculations
- Moshier analytical calculations
- VSOP87 analytical planetary models
- ELP2000 lunar theory
- Meeus analytical algorithms
This allows mixing:
- high-precision ephemeris kernels
- lightweight analytical calculations
- fallback computational modes
depending on accuracy and performance requirements.
What the Engine Supports
Currently implemented functionality includes:
- planetary calculations
- lunar calculations
- solar calculations
- eclipse calculations
- occultation calculations
- rise/set calculations
- sidereal systems
- ayanamsa support
- house system calculations
- fixed star calculations
- coordinate transformations
- time conversions
- nutation/precession
- topocentric calculations
API Surface
One important design goal was broad API coverage and extensibility.
Comparison
| Project | Public Functions | Public Constants |
|---|---|---|
| Swiss Ephemeris | 106 | 348 |
| JPL Moshier Ephemeris | 204 | 462 |
The engine fully covers the traditional Swiss Ephemeris-style public API surface while extending it with additional APIs and functionality.
Why MIT License Matters
Licensing was a major consideration from the beginning.
The project is MIT licensed to allow:
- open commercial use
- embedding into proprietary systems
- unrestricted integration
- easier ecosystem adoption
- broader language bindings
without GPL-style redistribution constraints.
Multi-Language Ecosystem
On top of the native engine, I also built:
JPL Moshier Ephemeris PHP
A PHP 8.3+ FFI wrapper with prebuilt runtime libraries for:
- Linux
- macOS
- Windows
The wrapper exposes the native engine directly to PHP while keeping deployment relatively simple.
Long-Term Vision
The larger goal is to build a complete open ephemeris ecosystem that can power:
- astronomy applications
- astrology software
- Panchang / almanac systems
- research tools
- calendar systems
- educational software
- cross-language scientific tooling
across multiple platforms and programming languages.
Project Links
Native C Engine
PHP Wrapper
jpl-moshier-ephemeris-php GitHub
Packagist
Feedback Welcome
The project is still evolving, and I’d genuinely appreciate:
- testing
- benchmarking
- API feedback
- architecture suggestions
- contributions
from developers working in astronomy, astrology, scientific computing, calendrical systems, or language bindings.
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