About Voyager Relativity
Voyager Relativity explores how time passes differently for Voyager 1 and Voyager 2 as they travel through deep space.
The project turns the trajectories of humanity's most distant spacecraft into a real-time relativity demonstration. Current and historical state vectors from the NASA/JPL Horizons system are used to compare an ideal clock travelling with either Voyager with an ideal reference clock on Earth. The calculation separates the effects of motion and gravity and follows their accumulated difference from launch to the present.
The goal is a small, accessible public science experience: part deep-space visualization and part relativity demonstration. The app was built through an incremental, three-party vibe-coding effort. Kees van Zon led the project, made the design decisions, provided the multilingual web app template, provided implementation prompts, and reviewed all changes. ChatGPT helped refine the concept, provided implementation prompts and reviewed the design and documentation. Codex created the code and provided scientific calculations, documentation drafts and translations.
Implementation summary
- OpenAI ChatGPT: GPT-5.6-sol High
- OpenAI Codex: GPT-5.6-sol High
- Website technology: C# and ASP.NET Core Razor Pages
- Trajectory data: NASA/JPL Horizons
- Languages: English, Dutch, German and Spanish
Credits
Inspiration
The idea for Voyager Relativity was suggested by Prof. D. Stanton of Cambridge, Massachusetts.
Mission facts and encounter dates
Based on NASA's Voyager mission overview, Voyager 1 and Voyager 2 pages.
Images
- Voyager 1: engineers installing the Golden Record cover on Voyager 1, 1977. Credit: NASA/JPL-Caltech (source).
- Voyager 2: engineers with Voyager 2 during testing, 1977. Credit: NASA/JPL-Caltech (source).
- Logo and icons: based on Logo sonde spatial.png by Jupiter75, via Wikimedia Commons. Modified for Voyager Relativity. Licensed under CC BY-SA 3.0.
Voyager Relativity is an independent project by Sunny Side Up Software. NASA and JPL provide mission information, imagery and ephemeris data but do not endorse or operate this website.