# Sky Viewer

Interactive planetarium at [/sky-viewer](/sky-viewer).

## Modes

| Mode | Description |
| --- | --- |
| **2D** | Stereographic sky map · pan / zoom · pick objects |
| **3D** | Celestial sphere · OrbitControls · detailed globes |
| **Explorer** | When Observation Center ≠ Earth — solar-system map / 3D |

## Observation Center

Choose the frame origin: Earth (geocentric sky), Sun, Moon, or a planet.

- **Earth** — classic alt/az sky from the observer  
- **≠ Earth** — Explorer view (orbits in AU + labeled bodies)  
- Changing center focuses the selection and opens Explorer when useful  

See [Explorer Mode](/guide/EXPLORER.md).

## Controls

| Action | How |
| --- | --- |
| Pan | Drag on canvas |
| Zoom | Mouse wheel · pinch · vertical slider · `+` / `-` / `0` |
| Hide UI | `H` (Show UI button restores) |
| Panels | `Ctrl+[` Settings · `Ctrl+]` Workbench |
| Search | Toolbar **Search** |
| Fullscreen | Toolbar **Full** |

FOV minimum is **15°** so the sky never collapses to an empty telephoto frame.

## Layers

Orbits · Constellations · DSO · ISS · Astrology  
Grids: Equator · Ecliptic · Galactic · Horizon · Meridian · RA · Dec  

## Workbench tabs

Overview · Observer · Time · Selected · Coordinates · Engine Debug  

Click a star or planet to open the object card (mag, RA/Dec, Az/Alt, rise/transit/set).