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Moon Phases

Calendaria supports multiple moons with configurable cycle lengths, phases, and colors.


Configure moons in Calendar Editor > Moons tab:

SettingDescription
NameMoon display name
Cycle LengthDays for one complete cycle
ColorTint color for icon display
Reference DateA known new moon date
Cycle Day AdjustFine-tune phase alignment
Reference PhaseWhich phase the moon is at on the reference date

Each phase carries:

  • Name: Phase name
  • Rising/Fading: Optional sub-phase names for multi-day phases
  • Icon: SVG path or emoji
  • Start/End: Cycle position

The phase slider in the Moons tab lets you adjust phase boundaries by dragging handles between segments. See Calendar Editor: Moon Phases.


A moon’s Phase Mode determines how its phase is calculated over time.

The moon follows a predictable, repeating cycle. The phase on a given day is determined by:

  1. Days since the most recent anchor (reset anchor preferred, otherwise a soft anchor or the calendar reference date)
  2. Position within the cycle. When each phase spans at least a day, this uses the midpoint of the current day; when a phase is shorter than a day, it uses the current time of day, so a moon whose cycle is shorter than the day length advances through its phases over the day
  3. The phase whose start/end range contains that fractional position

Phases repeat at exact intervals, producing a regular lunar cycle.

The moon follows an erratic, non-cyclical pattern driven by seeded randomness. The base cycle length still influences overall pacing, but the phase on any day varies unpredictably. This suits alien, magical, or chaotic moons.

Randomized moons are configured with:

SettingDescription
SeedInteger seed for randomization. The same seed always produces the same sequence. Use the dice button to randomize
Cycle VarianceControls how much the moon deviates from its base cycle length. At the low end it behaves like fixed mode; at the high end phases shift dramatically between days
Phase WeightPer-phase value controlling how likely a phase is relative to the others. A phase with double the weight occupies twice as much of the cycle

Anchor phases are date-specific phase pins. In Randomized mode they override the seeded phase on the anchor date. In Fixed mode they calibrate the cycle so the chosen phase begins on the anchor date, with Reset Cycle restarting the cycle from that point and non-reset anchors providing soft calibration.

Add anchor phases in Calendar Editor > Moons tab with Add Anchor Phase. Each anchor defines:

FieldDescription
YearThe display year to match. Leave blank for yearly recurrence
MonthThe month the anchor falls on
DayThe day of the month
PhaseWhich phase the moon displays on the anchored date

An anchor with no year repeats every year, pinning the chosen phase to that month and day.


When a phase spans multiple days:

  • First third: Rising name
  • Middle third: Main phase name
  • Last third: Fading name

Moon phases display on calendar day cells when Show Moon Phases is enabled for the MiniCal or BigCal. See Settings for the visibility controls.

BigCal shows a moon icon for each configured moon, tinted with its color. When there are many moons, a +X indicator counts the moons beyond the displayed icons.

MiniCal shows a single moon icon. A player clicks the icon to cycle through the configured moons.

The HUD dome renders moons with phase-accurate shadows and color glow. With Show All Moons enabled, secondary moons trail behind the primary moon at a smaller size.


Moons reduce nighttime scene darkness based on their phase. Each moon has a Brightness Contribution slider in Calendar Editor > Moons tab. The schema stores no value until you set the slider, but the editor display and the darkness calculation both treat an unset value as the default contribution.

Illumination follows a cosine curve: maximum at full moon, zero at new moon. Multiple moons sum their values up to a cap. Each moon’s light is tinted with its configured color.

Toggle moon illumination from the Canvas settings. See Scene Ambience: Moon Illumination for how this affects darkness calculations.


Configure moon-based recurrence through the condition builder on the note editor’s Schedule tab. Set the note to Recurring, open the condition builder or pick a moon preset, then add moon conditions to the condition tree:

ConditionDescription
Moon PhasePick a phase and the moon it applies to
Moon Sub-PhaseMatch Rising, True, or Fading for the selected moon

The moon is chosen per-condition, and the Rising/True/Fading distinction is the Moon Sub-Phase condition. Moon-phase count conditions are also available. There is no standalone repeat-pattern selector for moon phases.

See Notes and Events for more on recurrence patterns.


See API Reference and Hooks.