The real universe, drawn entirely in ASCII. An explorable WebGL atlas from Earth to the edge of the observable universe.
See the codeSee what people are saying
README
gcdatlas
The real universe, drawn entirely in ASCII. Live at https://gcdatlas.vercel.app
gcdatlas is an explorable atlas of the known universe where every frame is made of printable ASCII characters. Planets are where they are today, about 2,000 naked-eye stars sit at their measured distances, every active satellite circles the Earth, and one continuous zoom takes you from a city street's worth of sky to the edge of the observable universe.
- Denser glyphs mean more light. Colour comes from the physics: blackbody temperature, Doppler shift, emission lines.
- Black holes bend light (Schwarzschild ray tracing) above the true shape of their curved space (Flamm's paraboloid). Galaxies collide, binary stars trade gas, a star is torn apart, two black holes merge and ripple spacetime.
- The Halo, a long-range cruiser with a captured star for a heart, is the one invented thing here. Ride along behind it, or from its bridge.
How accurate is it? See docs/ACCURACY.md. The short version: positions, distances and sizes are real; the look of each object is a physically based artist's rendering.
Features
| Atlas and search | Type in the search box (or press /). Sort by distance, size or name, filter by kind (black holes, nebulae…), see what you have not visited yet, reset in one click. |
| Tours | Guided tours with captions. The play / pause button at the top right stops the camera so you can look around, and brings it back. ‹ › next to tours skip stops; while a tour plays the right-hand scale becomes the tour's track. Break away and resume tour takes you back. Choose how long each stop lasts. |
| Flybys | Sweeping camera moves past the giants (the Sun, UY Scuti, TON 618, the Milky Way…) that show their scale. |
| Scale ladder | Drag the marker to zoom from the Moon to the observable universe; let go near a name to fly there. |
| Time machine | Run the Solar System clock forwards or back, jump years, or drag deep time to watch the constellations change over ±200,000 years. |
| Tonight | Your sky: stand at your location and look up at the real sky. What is up tonight: Moon phase, bright planets, ISS passes, launches, meteor showers, eclipses. |
| Earth's story | 4.54 billion years on one slider: magma ocean, snowball Earth, the first forests, the asteroid, the first humans, today. |
| Live Earth | Every active satellite from CelesTrak's tracking data, the ISS and Hubble at their real positions, the next rocket launches at their pads, air traffic on real routes (simulated). |
| Screensaver | Full screen, the interface fades, an endless shuffled tour plays with the music (Z). Can start by itself after a few idle minutes. |
| Photo mode | Frame a shot, save it as a picture or copy it as ASCII text (P). |
| Today's discovery | One object a day, the same for everyone, with a streak. |
| Collection log | Ticks off what you have seen, with badges. Stored only on your device. |
| Music | gcd radio: a generative mix of lofi, chill house and ambient, synthesised live so it never loops. Pick a style or skip a track. |
| Share | Links reproduce your exact view, tour and date. |
| Calm interface | Fades after a few quiet seconds (sooner on tours) and comes back with any touch. The info panel can be full, compact or hidden (I). |
| Phones | A thumb-sized dock, the details as a card you can expand, shrink or swipe away, the scale ladder behind a chip, and the camera frames the object in the space left free. Works upright and on its side. |
Controls
| Input | Action |
|---|---|
| drag | orbit the camera (in your sky: look around) |
| scroll / pinch / + - | zoom |
| right-drag / shift-drag | pan |
| click or tap | fly to an object; once there it loops through its best angles until you take the camera |
/ | search |
[ ] | previous / next tour stop |
| W A S D, R F | fly freely |
| space or ❚❚ / ▶ (top right) | pause or play: the tour, or the angle loop of an object you picked |
| esc | close panels, then free camera |
| V · Y · T | detail · travel speed · time speed |
| G · L · M | glow · labels · music |
| Z · P · B | screensaver · photo mode · your sky |
Build and run
node build.mjs # writes dist/index.html (no dependencies, Node 18+)
npx serve dist # or open dist/index.html directly (live data needs the /api functions, see below)
npx vercel dev # the site plus the /api functions, as in production
Vercel runs the same build (see vercel.json); every push to main redeploys the site, and every pull request gets its own preview URL.
Tests (Playwright, headless Chromium):
npm install # dev dependencies only: playwright, sharp
npm test # smoke test: loads, renders every object, no errors
npm run test:tour # plays the grand tour for 1,000 simulated seconds
npm run shots -- sun:0,ton618:1 # screenshots of any objects / angles into tests/out/
npm run catalog # regenerates docs/CATALOG.md, the list of everything implemented
Where things are
| Path | Role |
|---|---|
src/00-head.html, src/01-body.html | styles and interface markup |
src/02-core.js … src/04-world.js | WebGL helpers, shared shader code and the ASCII pipeline, units, ephemerides, settings, feature flags, the object registry |
src/05-data.js | generated star catalogue and textures (tools/) |
src/06*.js, src/o*.js | the sky, galaxies, the cosmic web, and the built-in objects (one family per file) |
src/objects/ | content packs and add-ons (nebulae, galaxies, extreme stars, the black hole zoo, flybys, live Earth) |
src/07*.js | the Halo, transient events, music |
src/08*.js | camera, flights, tours, input |
src/09*.js | rendering, interface, atlas, features (screensaver, photo, collection, tonight, Earth's story) |
api/ | serverless functions: /api/sats (CelesTrak), /api/launches (Launch Library 2) |
tests/, tools/ | test harness, catalogue and data generators |
docs/ | architecture, accuracy, workflow, testing, security, roadmap, changelog, content catalogue |
Start with CLAUDE.md (working conventions) and docs/ARCHITECTURE.md.
Data and credits
- Star positions and parallaxes: Hipparcos, via star-catalog-lite; colours, constellation lines and the Milky Way outline: d3-celestial by Olaf Frohn
- Earth's coastlines: Natural Earth via world-atlas
- Planet orbits: JPL approximate Keplerian elements; body orientations: IAU WGCCRE
- Satellites: CelesTrak general perturbations data; launches: The Space Devs Launch Library 2
- Object facts and measurements: NASA, ESA, ESO and the published literature (see docs/ACCURACY.md)
Contributors
eshin087
83 commits
Similar repos
Languages
JavaScript
92.9%
HTML
7.1%
The real universe, drawn entirely in ASCII. An explorable WebGL atlas from Earth to the edge of the observable universe.
See the codeSee what people are saying
README
gcdatlas
The real universe, drawn entirely in ASCII. Live at https://gcdatlas.vercel.app
gcdatlas is an explorable atlas of the known universe where every frame is made of printable ASCII characters. Planets are where they are today, about 2,000 naked-eye stars sit at their measured distances, every active satellite circles the Earth, and one continuous zoom takes you from a city street's worth of sky to the edge of the observable universe.
- Denser glyphs mean more light. Colour comes from the physics: blackbody temperature, Doppler shift, emission lines.
- Black holes bend light (Schwarzschild ray tracing) above the true shape of their curved space (Flamm's paraboloid). Galaxies collide, binary stars trade gas, a star is torn apart, two black holes merge and ripple spacetime.
- The Halo, a long-range cruiser with a captured star for a heart, is the one invented thing here. Ride along behind it, or from its bridge.
How accurate is it? See docs/ACCURACY.md. The short version: positions, distances and sizes are real; the look of each object is a physically based artist's rendering.
Features
| Atlas and search | Type in the search box (or press /). Sort by distance, size or name, filter by kind (black holes, nebulae…), see what you have not visited yet, reset in one click. |
| Tours | Guided tours with captions. The play / pause button at the top right stops the camera so you can look around, and brings it back. ‹ › next to tours skip stops; while a tour plays the right-hand scale becomes the tour's track. Break away and resume tour takes you back. Choose how long each stop lasts. |
| Flybys | Sweeping camera moves past the giants (the Sun, UY Scuti, TON 618, the Milky Way…) that show their scale. |
| Scale ladder | Drag the marker to zoom from the Moon to the observable universe; let go near a name to fly there. |
| Time machine | Run the Solar System clock forwards or back, jump years, or drag deep time to watch the constellations change over ±200,000 years. |
| Tonight | Your sky: stand at your location and look up at the real sky. What is up tonight: Moon phase, bright planets, ISS passes, launches, meteor showers, eclipses. |
| Earth's story | 4.54 billion years on one slider: magma ocean, snowball Earth, the first forests, the asteroid, the first humans, today. |
| Live Earth | Every active satellite from CelesTrak's tracking data, the ISS and Hubble at their real positions, the next rocket launches at their pads, air traffic on real routes (simulated). |
| Screensaver | Full screen, the interface fades, an endless shuffled tour plays with the music (Z). Can start by itself after a few idle minutes. |
| Photo mode | Frame a shot, save it as a picture or copy it as ASCII text (P). |
| Today's discovery | One object a day, the same for everyone, with a streak. |
| Collection log | Ticks off what you have seen, with badges. Stored only on your device. |
| Music | gcd radio: a generative mix of lofi, chill house and ambient, synthesised live so it never loops. Pick a style or skip a track. |
| Share | Links reproduce your exact view, tour and date. |
| Calm interface | Fades after a few quiet seconds (sooner on tours) and comes back with any touch. The info panel can be full, compact or hidden (I). |
| Phones | A thumb-sized dock, the details as a card you can expand, shrink or swipe away, the scale ladder behind a chip, and the camera frames the object in the space left free. Works upright and on its side. |
Controls
| Input | Action |
|---|---|
| drag | orbit the camera (in your sky: look around) |
| scroll / pinch / + - | zoom |
| right-drag / shift-drag | pan |
| click or tap | fly to an object; once there it loops through its best angles until you take the camera |
/ | search |
[ ] | previous / next tour stop |
| W A S D, R F | fly freely |
| space or ❚❚ / ▶ (top right) | pause or play: the tour, or the angle loop of an object you picked |
| esc | close panels, then free camera |
| V · Y · T | detail · travel speed · time speed |
| G · L · M | glow · labels · music |
| Z · P · B | screensaver · photo mode · your sky |
Build and run
node build.mjs # writes dist/index.html (no dependencies, Node 18+)
npx serve dist # or open dist/index.html directly (live data needs the /api functions, see below)
npx vercel dev # the site plus the /api functions, as in production
Vercel runs the same build (see vercel.json); every push to main redeploys the site, and every pull request gets its own preview URL.
Tests (Playwright, headless Chromium):
npm install # dev dependencies only: playwright, sharp
npm test # smoke test: loads, renders every object, no errors
npm run test:tour # plays the grand tour for 1,000 simulated seconds
npm run shots -- sun:0,ton618:1 # screenshots of any objects / angles into tests/out/
npm run catalog # regenerates docs/CATALOG.md, the list of everything implemented
Where things are
| Path | Role |
|---|---|
src/00-head.html, src/01-body.html | styles and interface markup |
src/02-core.js … src/04-world.js | WebGL helpers, shared shader code and the ASCII pipeline, units, ephemerides, settings, feature flags, the object registry |
src/05-data.js | generated star catalogue and textures (tools/) |
src/06*.js, src/o*.js | the sky, galaxies, the cosmic web, and the built-in objects (one family per file) |
src/objects/ | content packs and add-ons (nebulae, galaxies, extreme stars, the black hole zoo, flybys, live Earth) |
src/07*.js | the Halo, transient events, music |
src/08*.js | camera, flights, tours, input |
src/09*.js | rendering, interface, atlas, features (screensaver, photo, collection, tonight, Earth's story) |
api/ | serverless functions: /api/sats (CelesTrak), /api/launches (Launch Library 2) |
tests/, tools/ | test harness, catalogue and data generators |
docs/ | architecture, accuracy, workflow, testing, security, roadmap, changelog, content catalogue |
Start with CLAUDE.md (working conventions) and docs/ARCHITECTURE.md.
Data and credits
- Star positions and parallaxes: Hipparcos, via star-catalog-lite; colours, constellation lines and the Milky Way outline: d3-celestial by Olaf Frohn
- Earth's coastlines: Natural Earth via world-atlas
- Planet orbits: JPL approximate Keplerian elements; body orientations: IAU WGCCRE
- Satellites: CelesTrak general perturbations data; launches: The Space Devs Launch Library 2
- Object facts and measurements: NASA, ESA, ESO and the published literature (see docs/ACCURACY.md)
Similar repos
Contributors
eshin087
83 commits
Languages
JavaScript
92.9%
HTML
7.1%