A real-time planetarium I've been building in my spare time. Open to corrections.
Hi everyone,
I'd love to share a project I've been pouring myself into for the past few weeks: kintana.dev. It started out as an immersive screensaver displaying a starry sky in the background of my screen, but it grew into a real-time planetarium, and that's mostly what I want to show you today.
The idea of the planetarium: pick any spot on Earth (Atacama, your backyard, Pic du Midi, wherever), pick any date (past or future), and the sky appears exactly as it unfolds there at that moment. You can fast-forward time to watch stars rise and set, zoom into a nebula, or search for a specific star by name.
What's real
I tried to take the data seriously.
- 108,000 stars from the HYG v4.1 catalog with their real positions, real apparent magnitudes, and real B-V colors.
- Planets (Mercury, Venus, Mars, Jupiter, Saturn, Sun) propagated in real time using JPL mean elements, accurate to within an arc-minute over ±50 years from J2000.
- The Moon uses Meeus's truncated series; its phase is computed correctly and you can even see earthshine on thin crescents.
- Six major meteor showers (Perseids, Geminids, Leonids, Lyrids, Orionids, Quadrantids) all radiate from their real radiants.
- M31, M42, the Pleiades, the Magellanic Clouds, and about twenty other deep-sky objects are placed at their real coordinates with real photographs.
- Zodiacal light appears along the ecliptic in Bortle 1 to 3 skies.
Tech
The whole thing runs through WebGL via Three.js with a custom stereographic projection shader: about 700,000 points on the GPU at 60 fps. The site is available in over 40 languages (top-right language picker in the settings). It's free, no account, no ads, no tracking, and it'll stay that way.
Known limitations
- No atmospheric refraction yet.
- No extinction either, so a star at the horizon is rendered just as bright as one at the zenith, which isn't true in reality.
- The Milky Way is procedural: the right hotspots at the right galactic longitudes, but not an actual photograph.
- The Sun renders even at local noon because it's always night mode, by design.
Feedback welcome
If there are astronomers, astrophotographers, or just enthusiasts passing through, I'd love your feedback. If something breaks the immersion (a planet color that looks off, a magnitude that feels wrong, a weird orientation, anything that sounds fake), let me know in the comments and I'll fix whatever can be fixed.
Thanks.