“As is natural and proper, all other worlds revolve around our own planet Oerth, from the least rock to the vast burning sun itself. Little is known of these worlds, though a set of magnifying lenses or magical cusps reveals their curious shapes and colors, and their motions across the sky are well charted. As any rational individual knows, these ‘wandering stars’ influence the lives of all beings on Oerth, and their positions against the vault of night give hints to learned astrologers about events yet to come, revealing secrets fearful and sublime.

Oerth rotates on its axis once every 24 hours. The sun travels the sky from east to west, revolving clockwise in its orbit around Oerth to make a full circuit of the heavens every 364 days, following a fixed path through the Twelve Lairs of the Zodiac. Through the Zodiac of the night sky also pass the Great Moon of Oerth, known as Luna, and the Lesser Moon, Celene, also called the Handmaiden. Ghost-white Luna waxes and wanes in a fixed cycle of 28 days, reaching fullness 13 times each year. Aquamarine Celene passes through its phases more slowly, taking 91 days for a full cycle and reaching fullness only four times a year. These natural rhythms are reflected in the calendar used by civilized inhabitants of our land.

It is known that when both Luna and Celene are either full or new, and the wandering stars have themselves achieved positions of power within the Zodiac, events of great portent are likely to occur on our world. The fate of civilization may be in the balance, and the involvement of great magic is almost certain. The appearance of a falling star has further significance, and a great pale comet or bright exploding star hovering in the darkness is a harbinger of cataclysm.

More will be said about the place of our grand world in the hierarchy of the heavens, but we first turn to an analysis of the Zodiac and the special influence of its lairs on our Oerth, first described by Baklunish astrologers two millennia ago...”

— Agath of Thrunch, from Understanding the Handiwork of Celestian

The Overking's Common Calendar

Most reckoning is dated by Common Year (CY), a system which commenced when the Overking of Aerdy declared universal peace through the whole of the Great Kingdom. Chronologies given elsewhere, however, include five other calendars which were once used and are sometimes referred to in ancient writings. Some few nations still employ these superannuated reckonings, as do the more isolated elvenfolk. 

The following describes the standard calendar familiar to the civilized inhabitants of the Flanaess. The calendar used here is very old, much of it predating the founding of the Great Kingdom in the year 1 CY. It is important to note that the Common Year calendar does not have a “zero year.’ Most historians of the Flanaess use other dating systems when talking about ancient history. 

The standard week of seven days has the following days:

• Starday — Work
• Sunday — Work
• Moonday — Work
• Godsday — Worship
• Waterday — Work
• Earthday — Work
• Freeday — Rest

A month consists of 28 days, divided into four weeks of seven days each. The month's length is based on the period of Oerth's Great Moon, Luna. A year is divided into twelve months (called a Dozenmonth), further divided into four groups of three months each, separated by weeklong Festivals, for a total of 364 days. The timing of the Festivals is determined by the period of the lesser moon, Celene; the fourth (middle) day of each Festival is when Celene is full. The dates of each full Luna wander through the year as the Festival weeks throw off the calendar cycle, though at least they do so on a predictable basis. The Dozenmonth of the moon and the four Festivals (shown in italics) follow.

Calendar Years

A year may be written with the calendar system abbreviation before or after the date — for instance, 576 CY or CY 576, according to the writer's whim. Because the Common Year calendar has no zero year, it is very rare to write dates with negative CY numbers, as one year will be missing when calculating the time between a negative and positive CY year (for instance, 19 years, not 20 years, elapsed between the 1st of Goodmonth in —10 CY and the same date in 10 CY). To avoid confusion, another calendar is used for dates before 1 CY, most often the Oeridian Record (OR), as it was widely understood and used long after the founding of the Great Kingdom. Other calendars may be used if the subject matter makes the substitution appropriate.

The current year is now early spring 576 CY. This year is 1220 OR in the Oeridian Record calendar, 6091 SD in the Suloise Dating system of the old Suel Imperium, 5038 OC in the Olven Calendar, 3235 BH of the Baklunish Hegira calendar and 2726 FT in Flan Tracking. It has been 997 years since the Invoked Devastation and Rain of Colorless Fire destroyed the Baklunish Empire and Suel Imperium.

Annual Events

This following describes the major annual events commonly recognized in the Flanaess, focusing on the four festival weeks of the calendar year. Only the most significant and widely celebrated religious holidays are given here. In addition, each religion has its own set of holy days in addition to this list, and each realm and settlement celebrates its own secular holidays, most of them of minor importance elsewhere.

Needfest: This frigid seven-day period marks the transition from one calendar year to another, and it is usually accounted as the start of the new year. In many areas in the Flanaess, the week is spent feasting, drinking, dancing, gift-giving, putting up lights and decorations, and in revelry. Many religions celebrate midwinter with good deeds, charity, or observations of the sky.

Great Moon's Glory: On Readying 11th, Luna is full, but Celene is new. This night is called Great Moon's Glory. The Church of Celestian regards this night as especially holy, holding an all-night outdoor vigil of the heavens. Oeridians make offerings to shrines to the lesser goddess Atroa on this night, asking the Queen of Spring to come early. Offerings to shrines to Telchur (the Oeridian god of the north and winter) are also made, praising his work but suggesting he go home to the pole and sleep. Local druids and their small congregations also hold this night sacred, but little is known of their activities. Many farmers and herdsmen mark this night as the true beginning of spring, though Readying 1st is the calendar date for spring's start.

Growfest: Growfest is regarded as a time of good cheer with the full arrival of spring. The weather is usually blustery, with cool sunny days alternating with heavy rain, Farmers, herders, longshoremen and other workers prepare for the upcoming busy summer, and merchant activity is high. Growfest 4th, Godsday, is St. Cuthbert's Day, the largest annual festival celebrated by those of that faith.

Richfest: During the hot, breezy week of Richfest is when most people take off to celebrate the height of summer and give thanks to the appropriate gods for any good fortune they've had. Midsummer Day is called the Holy Day of Pelor. Pelor — master of the sun, light, and healing — is beloved of many of the Flanaess's populace, and this day sees large religious festivals in his honor.

Midsummer Night: The evening of Richfest 4th is Midsummer Night. Both moons are full, and at midnight Celene eclipses Luna. This is a portentous evening, sacred to many religions, and sometimes astronomical phenomena are seen that hint at future events, good and ill, This is the best night of all for druids to collect mistletoe, but it is also the night on which the greatest number of werewolves are out, as the combined effect of the two moons makes it nearly impossible for lycanthropes to avoid were-change.

Dark Night: Both moons of Oerth are new on the night of Goodmonth 11th (always a Godsday), which earns this evening various titles such as the Dark Night, Black Night or Star Night. While certain religious groups spend the night observing the skies for portents (or taking advantage of its darkness for acts of evil or thievery), many ordinary folk light all-night bonfires.

Brewfest: Many citizens take this fall celebration of the last harvest completely to heart, and public intoxication is common. Cities take on a circus atmosphere, and the streets are filled with actors, jugglers, acrobats, animal and monster trainers (with their best “pets”), and grinning adventurers showing off their latest trophies. The festival is celebrated throughout the Flanaess.