star-map

An interactive 3D star map in the spirit of Star Citizen's in-game starmap, but populated with real astronomical data instead of fictional systems. Browse the solar neighbourhood, fly into a star's system to see its planets on their real orbits, and drill into a single body for the NASA figures behind it.

This repo also hosts a small Claude Code plugin marketplace — see Plugins below.

Running it

npm install
npm start          # dev server on http://localhost:4200
npm run build      # production bundle into dist/

Requires the Node version in package.json's Angular toolchain range (Node 22.22.3+ or 24.15+).

npm test               # unit/component tests (Vitest, jsdom)
npm run e2e            # end-to-end tests (Playwright + Chromium) — see e2e/README.md
npm run etl            # refresh the astronomical datasets — see below
npm run etl:typecheck  # type-check the ETL scripts (they build separately from the app)
npm run e2e:typecheck

What's in it

Galaxy view — every HYG-catalogue star within 50 parsecs as instanced camera-facing billboards, positioned from real RA/Dec/parallax, coloured by spectral index and sized by magnitude. A polar grid in the galactic plane runs under them with a drop line from each of the Sun's nearest neighbours, and names label the stars nearest whatever the camera is looking at. Behind them sits a backdrop of notable deep-sky objects and a Milky Way panorama.

Galactic view — keep pulling back and the neighbourhood becomes a point inside the Milky Way: the bar and bulge, five spiral arms, the disc and a thin halo, with the arms and the galactic centre named. It is the same parsec-scale space as the galaxy view, crossfaded by camera distance rather than switched, so the Sun stays where it really is — 8.18 kpc out, on the Orion Spur, between the Sagittarius and Perseus arms. See "On the Galaxy model" below for what in it is measured and what is not.

System view — selecting a star flies the camera continuously into its system rather than cutting to a new scene. The Sun gets the real solar-system bodies from JPL Horizons; other stars get their confirmed exoplanets. Orbits are drawn as ellipses and bodies are propagated along them by a Kepler solver against the current epoch.

Body detail — a dedicated close-up scene and info panel for one planet, moon or exoplanet, with real photography where NASA/ESA/USGS imagery exists.

Search — name search across stars, solar-system bodies and exoplanets, navigating to the same place an in-scene click would.

Architecture notes

• Rendering runs on Three.js WebGPURenderer, which falls back to a WebGL2 backend automatically. The render loop runs outside Angular's change detection.
• Stars are billboards, not points. The WebGPU backend caps point primitives at a single pixel, so a points cloud renders every star as an identical dot regardless of magnitude. The star field is instanced quads on a SpriteNodeMaterial instead, which behaves the same on both backends. Their size is angular rather than world-space — real stars are unresolvable point sources, so apparent size should follow brightness, not distance.
• One reference frame, from three sources. HYG gives star positions in equatorial J2000. JPL Horizons reports orbital elements against the ecliptic, tilted 23.4° away. The Exoplanet Archive measures inclination from the plane of the sky — perpendicular to our line of sight to each host star, which is why transiting planets cluster at 90°. Each set of elements is rotated from its own reference plane into the scene's equatorial frame, so a direction means the same thing everywhere. Systems are still presented face-on — by placing the camera relative to the orbital plane rather than by rotating the world into a convenient pose.
• Two coordinate scales. The galaxy view works in parsecs and the system view in AU — about eight orders of magnitude apart, which wrecks float precision if rendered in one unit space. The camera rig recentres the active star to the origin ("floating origin") and swaps the unit scale and near/far planes at the transition point.
• The galactic scale is not a third space. It is the same parsec space as the galaxy view, four orders of magnitude further out, so no swap is needed — the Milky Way model and the catalogued star field crossfade against camera distance and the depth range scales with it. One fixed near/far pair cannot serve both ends: flying into a star needs a near plane a hundredth of a parsec out, and holding the Galaxy needs a far plane a hundred thousand parsecs out, and a projection spanning both has no precision left to separate one arm from the next.
• No backend. Every dataset is baked at build time into src/assets/data/ and served as a static asset. Nothing queries an astronomy API at runtime.

On the Galaxy model

Every other dataset here is measured. The Galaxy is the exception, and not for want of trying: we sit inside its disc, and dust blocks the view across it, so no catalogue holds the positions of its stars. Every rendering of the Milky Way seen face-on — including NASA's — is a model.

What is measured is the skeleton, and that is what shared/astro/galaxy.ts contains: the directions of the galactic centre and the north galactic pole, which fix the disc's 63° tilt against the celestial equator; the 8.18 kpc from the Sun to the centre, from the orbit of the star S2 around Sgr A*; and a reference radius, azimuth and pitch angle per spiral arm, approximating the maser-parallax fits. The Sun's placement on the Orion Spur and the arms either side of it follow from those numbers rather than being posed by hand.

The particles scattered around that skeleton are illustrative — a seeded, reproducible cloud, not observations. The galactic view says so on screen, and the model fades out entirely before the camera reaches the catalogued 50 pc the real stars occupy.

Data pipeline

npm run etl runs tools/etl/build.ts, which fetches each source, writes the static assets, then validates the combined output. Raw responses are cached under tools/etl/.cache/, so re-runs are cheap and offline-friendly; set ETL_FORCE_REFRESH=1 to bypass the cache.

Script	Source	Output
fetchStars.ts	HYG database (Hipparcos/Yale/Gliese)	stars.bin, stars-index.json
fetchSolarSystem.ts	JPL Horizons / SSD	bodies.json
fetchExoplanets.ts	NASA Exoplanet Archive (TAP)	exoplanets.json
fetchDeepSky.ts	OpenNGC	deepsky.json

Star positions ship as a packed Float32Array (stars.bin) rather than JSON to keep the initial payload and parse cost down; stars-index.json carries everything else in the same order.

ETL_STAR_DISTANCE_PC (default 50) sets the star-field distance cutoff.

On deep-sky distances

OpenNGC publishes no distance column, so distance has to be inferred — and the inference fails for precisely the best-known objects. M31, M33 and M42 are Local Group members whose redshift is negative or absent, and the catalogue's parallax for a galaxy comes from a cross-matched foreground star (it lists 6 mas for M31, implying 167 pc for something 780,000 pc away).

So deep-sky records store a unit direction on the celestial sphere rather than a position: the line of sight is always known precisely, and the objects are drawn as a fixed-radius backdrop shell where true distance would be unusable anyway. distancePc is optional metadata, derived from parallax for galactic objects or the Hubble law for genuinely distant galaxies, and left null — with its distanceMethod — whenever neither is trustworthy. Roughly 330 of the 463 cataloged objects get a distance; the rest honestly report none.

Layout

src/app/
  core/engine/          Three.js renderer, render loop, resize
  core/data/            static-asset loading and caching
  features/galaxy-system/  shared galactic+galaxy+system scene, camera rig, star field,
                           Milky Way model, grid planes, deep-sky backdrop, orbits,
                           labels, HUD
  features/body-detail/    close-up scene and info panel
  features/search/         name search across every dataset
  shared/astro/         coordinates, Kepler propagator, deep-sky classification,
                        Milky Way structure
  shared/models/        record contracts shared by the app and the ETL
  shared/rendering/     skybox, glow sprites, texture catalog
  shared/state/         navigation store (Angular signals)
tools/etl/              build-time data pipeline
e2e/                    Playwright end-to-end tests

The design document behind all of this is .junie/plans/nasa-star-map.md.

Plugins

This repo doubles as a Claude Code plugin marketplace. Adding it and installing a plugin defaults to user scope, meaning the plugin becomes available in every project on your machine, not just the one you happen to be in:

/plugin marketplace add avalon-vanguard/star-map
/plugin install caveman@star-map

Scope can be overridden at install time if you want it tied to a single repo instead:

# Shared with collaborators via that repo's .claude/settings.json
/plugin install caveman@star-map --scope project

# Just for you, in that one repo only (gitignored)
/plugin install caveman@star-map --scope local

See Claude Code plugin installation scopes for details on user / project / local scope.

• caveman — /cs:caveman ultra-compressed communication mode.
  • Command: commands/cs/caveman.md
  • Agent: agents/cs-caveman-mode.md
  • Skill: skills/caveman/SKILL.md

Data credits

Star catalogue: HYG database (Hipparcos, Yale Bright Star, Gliese). Solar-system ephemerides: NASA/JPL Horizons. Exoplanets: NASA Exoplanet Archive. Deep-sky objects: OpenNGC. Body and skybox imagery: NASA/JPL/USGS public domain and Solar System Scope (CC BY 4.0) — per-file provenance is recorded in src/app/shared/rendering/texture-catalog.ts.