| name | uds-sun-moon-stars |
| description | Control the sun, moon, stars, aurora, sky glow, and space layer (planets/moons/nebula) in Ultra Dynamic Sky. Covers sun/moon path (Yaw, Pitch, Vertical Offset, Moon Orbit Offset), manual positioning with Sun/Moon Target widgets, sun appearance (scale/softness/color/eclipse), moon appearance and phases, Stars (tiling vs 360 starmap), 2D and Volumetric Aurora, Night Sky Glow + Light Pollution, and adding planets/moons/nebula via the Space Layer. Use whenever the user asks about sun/moon position, where the sun rises, manual sun placement, moon phases, stars not appearing, aurora effects, light pollution, or adding visible planets/moons — even phrased generally like "I want a giant moon" or "how do I get aurora borealis". |
| metadata | {"asset":"Ultra Dynamic Sky (marketplace)","category":"celestial-bodies","source-docs":"https://www.ultradynamicsky.com/Documentation/V9/9-5"} |
UDS sun, moon, stars, aurora, space
UDS owns five distinct visual layers above the cloud layer — sun, moon, stars, aurora, and the Space Layer (planets/moons/nebula) — plus a global sky-glow contribution at night. For sun/moon as directional lights, see uds-lighting-and-shadows. For real-world astronomical positioning, see uds-simulation.
| Element | Category | Notes |
|---|
| Sun position/path | Sun | Yaw/Pitch/Vertical Offset; Manually Position takes priority |
| Sun appearance | Sun | Scale, softness, color, intensity, Solar Eclipse, source angle |
| Moon position/path | Moon | Same axes plus Moon Orbit Offset |
| Moon appearance | Moon | Two textures (RGB + Phase Normal), Render Moon Phases toggle |
| Stars | Stars | Tiling stars by default; 360 star map when Simulate Real Stars is on |
| 2D Aurora | Aurora | Sky-material shader; needs Use Auroras + a compatible Sky Mode |
| Volumetric Aurora | Sky Mode = Volumetric Aurora | Full 3D, camera can fly through; disables clouds |
| Night Sky Glow | Sky Glow | Uniform light to the night sky and clouds (from above) |
| Light Pollution | Sky Glow | Light to night sky and clouds (from below) — urban glow |
| Space Layer | Space Layer | Planets/moons/nebula via DBuffer mesh decals |
When to use this skill
- Setting where the sun rises/sets, or how high it goes.
- Disconnecting sun/moon position from time and placing it freely.
- Tuning the sun disc (scale, softness, color, eclipse behavior).
- Working with moon phases or swapping the moon texture.
- Replacing the stars texture or enabling the 360 star map.
- Adding aurora — 2D or volumetric.
- Keeping a night scene from going pitch black without moonlight (sky glow / light pollution).
- Adding visible planets, moons, or nebula in the sky.
Sun and moon movement
Without Simulate Real Sun/Moon (the simulation overrides these), sun/moon paths come from these per-body settings:
| Setting | Effect |
|---|
Yaw (Sun Yaw / Moon Yaw) | Yaw of the circular path in degrees (CW). Determines rise/set direction. |
Pitch (Sun Pitch / Moon Pitch) | Pitches the path so zenith angles away from straight up. 0 = passes directly overhead. |
Vertical Offset (Sun / Moon Vertical Offset) | Positive/negative shift, raises/lowers regardless of time |
Moon Orbit Offset (moon only) | Offset in time from the sun. 0 = path is exactly opposite the sun's. |
All ignored when simulation is on (see uds-simulation).
Manually positioning the sun / moon
To disconnect the body from time and place it freely:
- In the Sun category, enable
Manually Position Sun Target (or the moon equivalent in Moon).
- In the level viewport with UDS selected, find the blue diamond widget labeled Sun Target or Moon Target.
- Move the widget. The body points from the UDS actor toward the widget's position.
The widget drives Sun Target / Moon Target vectors in the advanced dropdown of the Sun/Moon categories. Setting them at runtime moves the body.
Manually Position takes priority over the simulation — it's the highest-priority positioning method.
Sun appearance
Rendered as a radial gradient. Settings in the Sun category:
| Setting | Purpose |
|---|
| Scale, softness, color, intensity | Disc appearance |
Sun Source Angle Scale | Multiplier over the calculated source angle. The angle drives shadow softness + specular size. |
| Solar Eclipse settings | What happens when the moon, or a Space Layer object, crosses in front |
For the filmic Sun Lens Flare effect (separate from engine post-process lens flare), see uds-modifiers-configs-state.
Moon appearance and phases
Settings in Moon. Two textures:
| Texture | Purpose |
|---|
Moon Texture | RGB color + alpha of the moon |
Moon Phase Normal | RGB normal map for shading the lit/unlit sides during phase rendering |
To use a non-phased custom moon texture (e.g. a giant alien moon), disable Render Moon Phases.
Moon Phase controls the current phase. The Moon category has an option to change phase over time automatically. With Simulate Real Moon, phase is driven by the simulation.
Stars
Settings in Stars.
| Texture variable | When used |
|---|
Tiling Stars | Default; simple repeating texture |
Real Stars | Used automatically when Simulate Real Stars is on; 360° star map |
Both swappable. Also in this category: stars color, intensity, atmospheric twinkling.
Aurora
Two delivery methods sharing colors/movement settings in the Aurora category.
| Type | How to enable | Mental model |
|---|
| 2D Aurora | Use Auroras in Aurora category, with a compatible Sky Mode that isn't Volumetric Aurora | Sky-material shader effect drawn with textures. Settings in Aurora advanced dropdown. |
| Volumetric Aurora | Sky Mode = Volumetric Aurora | Rendered via the volumetric cloud component. Full 3D, camera can fly through. Disables clouds. |
Sky Glow
Category: Sky Glow — adds illumination to the night sky independent of moon/sun.
| Setting | Effect |
|---|
Night Sky Glow | Uniform light added to the sky material; subtly lights volumetric clouds from above. Imitates ambient starlight + atmospheric glow. Raise to keep night scenes from going too dark without moonlight. |
Light Pollution | Adds light to the sky material; softly lights volumetric clouds from below. Imitates urban sky glow. |
Space Layer (planets, moons, nebula)
Category: Space Layer. Renders into the sky layer with correct compositing: planets occlude stars, but clouds and aurora obscure them.
Add planets:
- Manually via the Planets / Moons array.
- Via Add Planet / Moon Preset for drop-in starting points.
| Per-planet setting | Effect |
|---|
Parent | What the planet moves with: Sun, Moon, or unparented |
Relative Rotation | Orientation relative to the parent |
Scale | Visual size |
Terminator | The line between lit and dark sides |
Light Vector | What determines the lit side: sun, moon, or custom vector |
Glow | Diffuse atmospheric glow around the planet. Brightness rises with how much of the lit side faces camera. Scaled globally by Space Glow Brightness in the Space Layer category. |
Unparented planets can be moved manually at runtime via the components in the Space Roots array on UDS.
Nebula
Also in the Space Layer category. Rendered into the sky material the same way as planets/moons. Noise-based with adjustable colors, scale, intensity.
Space Layer requirements (DBuffer Decals)
The Space Layer renders via DBuffer mesh decals sampled in the sky material — that's what allows correct compositing within the sky layers.
| Renderer | Project setting that must be on |
|---|
| Desktop | DBuffer Decals |
| Mobile | Mobile DBuffer Decals |
If Space Layer renders nothing, this is almost always the cause.
Runtime / Blueprint scripting
Most positioning/appearance properties are static properties — runtime changes don't apply until you call Static Properties - Sun, Static Properties - Moon, etc. For an instant full refresh, Hard Reset Cache. See uds-performance-mobile-troubleshooting.
Animatable / responsive at runtime without extra calls:
Time of Day (drives sun/moon position normally)Sun Target, Moon Target (when Manually Position is on)Moon Phase- Active colors/intensities that vary with time (cache handles automatically)
For materials that need to know which body is currently the dominant light source: Active Sun or Moon Vector material function — outputs a unit vector pointing toward whichever body is up (sun by day, moon by night), plus a 0–1 mask that drops to 0 at the swap moment (multiply effects by it to hide pop artifacts).
Gotchas
- Planets/moons/nebula not rendering —
DBuffer Decals (or Mobile DBuffer Decals) project setting is off, or the platform doesn't support DBuffer mesh decals.
- Stars look pixelated and tiled — that's the default
Tiling Stars texture. Enable Simulate Real Stars for the 360 star map. (Or swap Tiling Stars for a higher-res texture.)
- Sun/moon position settings ignored —
Simulate Real Sun/Moon is on, which overrides them. Or Manually Position Sun/Moon Target is on, which overrides everything.
- Moon phase wrong / not changing —
Simulate Real Moon is on, which controls phase from the simulated date.
- Aurora not visible in a mode that should support it —
Use Auroras is off in the Aurora category, or the Sky Mode is Volumetric Aurora (which disables 2D aurora drawing).
- Volumetric clouds invisible after switching to Volumetric Aurora — expected; Volumetric Aurora disables clouds. Pick another mode if you need both (no UDS mode renders both volumetrically).
- Setting
Sun Scale at runtime has no visible effect — Sun Scale is a static property; call Static Properties - Sun.
References & source material
Docs (Ultra Dynamic Sky 9.5):
Plugin asset paths:
- Component list on the UDS actor: Sun, Moon, Sky Light light components
Space Roots array on UDS — components that hold unparented Space Layer items at runtime
Related skills: uds-simulation, uds-setup-and-modes, uds-time, uds-lighting-and-shadows, uds-modifiers-configs-state.
