Ue Uds Sun Moon Stars

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 ue-uds-lighting-and-shadows. For real-world astronomical positioning, see ue-uds-simulation.

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:

All ignored when simulation is on (see ue-uds-simulation).

Manually positioning the sun / moon

To disconnect the body from time and place it freely:

1. In the Sun category, enable Manually Position Sun Target (or the moon equivalent in Moon).
2. In the level viewport with UDS selected, find the blue diamond widget labeled Sun Target or Moon Target.
3. 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:

For the filmic Sun Lens Flare effect (separate from engine post-process lens flare), see ue-uds-modifiers-configs-state.

Moon appearance and phases

Settings in Moon. Two textures:

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.

Both swappable. Also in this category: stars color, intensity, atmospheric twinkling.

Aurora

Two delivery methods sharing colors/movement settings in the Aurora category.

Sky Glow

Category: Sky Glow — adds illumination to the night sky independent of moon/sun.

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.

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.

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 ue-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):

• Adjusting Sun and Moon Movement
• Manually Positioning the Sun and Moon
• Sun Appearance
• Moon Appearance and Phase
• Stars
• Aurora (2D + Volumetric)
• Sky Glow
• Adding Planets / Moons / Nebula Using the Space Layer
• Common Issues — Space Layer Not Rendering

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: ue-uds-simulation, ue-uds-setup-and-modes, ue-uds-time, ue-uds-lighting-and-shadows, ue-uds-modifiers-configs-state.