Adobe InDesign
Calendar Wizard

by Scott Selberg

Advanced Features: Moons

The calendar wizard can insert a graphic representing the phase of the moon. The moon graphic comes in two varieties: a circle with a stroke and fill representing the full and new moon, two adjoining half-circles representing the half moons. For the grid and line calendar, the moon graphic is inserted into a new layer. The moon graphic is placed in a cell of the list calendar.

Moon Settings

Moon Size: Determines how large the graphic will be as a percentage of the cell it is created in.

Moon Rotation: From the perspective of an observer in the northern hemisphere, the right side of the moon will be the side first visible after a new moon and the light will continue to grow from right to left. To an observer in the southern hemisphere, the opposite is true. It will be the left side of the moon that shows light first and it will grow left to right. If you think of the letters D, O and C graphically showing the moon phases (where O is the full moon), the observable pattern in the north is DOC and the the south it is COD.

Styling of the Moon

There are 6 colors used in the moon graphics.

In CS3 and earlier, the colors are directly applied to the graphic objects; starting with CS4, the Wizard will applies them via object styles:

Accuracy of the Moon Phases

Determining the phase of the moon via a calculation is not simple. Starting with version 5, the Calendar Wizard uses a refactoring of the basic code from the March, 1985 issue of Sky & Telescope Magazine to determine the phase of the moon. The algorithm is pretty good for determining the dates for the new and full moons based on observing the moon from the prime meridian (GMT/UTC time). It is less accurate with the half moons and can be either early or late by a day.

For an accurate inclusion of the moon phase with respect to your time zone there is an alternative. A special holiday file can be used to explicitly set the dates for the full, new and half moons. The name of the holidays file must start with "Moons", after that any text may follow. Within the file, only four types of holidays are valid: full, last quarter, new, first quarter.

Here is a short example:

1-13-2015:last quarter
1-26-2015:first quarter

2-11-2015:last quarter
2-25-2015:first quarter

When using a holiday file to specify the moons, the wizard will only insert the moons on the dates provided. If the wizard is creating a calendar from Dec 2015 - Jan 2017 and the moons file only contains dates for 2016, there will be no moons shown in the Dec 2015 or Jan 2017 calendars.