A real-ephemeris 3D universe explorer in the browser

I built a free 3D universe explorer that runs in the browser. This one is different, promise. :)

Planet positions come from real ephemerides (astronomy-engine), the ~118k star catalog has proper motion, and the spacecraft fly their actual JPL Horizons trajectories. A surface mode puts you on Earth, the Moon or Mars and renders the sky from there. Keep zooming out and you pass the nearby stars, the Milky Way, and the local galaxy clusters, ending at the cosmic microwave background.

No account, no backend, everything runs client side.

It also stages many real events. Ex: Shoemaker-Levy 9 impact week replays on the actual July 1994 timeline, each fragment hitting Jupiter at its recorded time. Solar eclipses cast the Moon's real umbra on Earth, so you can watch the Aug 2026 eclipse shadow cross the Atlantic from orbit.

Tech is Three.js + React + Zustand. All the heavy data (star catalogs, baked trajectories, eclipse tables) is precomputed at build time, so it works without a server and there's nothing to scale.

It's a solo project and I'm still adding to it weekly. Tell me what's missing or what's broken and I'll add it or fix it!