Lunar and Stellar Calendars

All references to the Zodiac refer to the Elven Zodiac of thirteen signs, and not the clumsy human zodiacal system of fourteen signs including the so-called Void, which is not a constellation at all, but merely a nihilistic absence of light.

This page does not detail actual Elven Calendars, merely the celestial influences behind their creation.

Months

Synodic Month

Each cycle from Full Moon to New Moon and back is one Synodic Month. This is an average of 28 days, and there are approximately 13 Synodic Months to a Seasonal or Synodic Year. Over a Saros Cycle of 18 years the variations cancel out. The Synodic Calendar Month is 28 days, which is an artificial construct taking advantage of this variation cancelling. It is also known as a Lunar Month (which is confusing, as all months are lunar cycles). This month passes through the same Zodiac sign in its first two and last two days, and so the thirteen months in a year are often referred to by their signs.

Sidereal Month

It takes exactly one Sidereal Month for the Sun to gain one Zodiac Sign on the Moon. This is almost identical to the time taken for the Moon to pass through all the signs of the Zodiac (the Stellar Month), and the two are often confused. There are approximately fourteen Sidereal Months to a Sidereal Year. Over a Saros Cycle of 18 years the variations cancel out. The Sidereal Calendar Month is 26 days, which is an artificial construct taking advantage of this variation cancelling.

Draconic Month

A Draconic Month is the period between consecutive times the Moon crosses the elliptic from South to North. It is slightly shorter than a Sidereal Month at an average of 25 days 16 hours 39 minutes and 32 seconds.

Anomalistic Month

An Anomalistic Month is the period between apogees, which occur when the Moon is at its maximum distance from Alusia. It is slightly longer than a Sidereal Month at an average of 26 days 17 hours 49 minutes 42 seconds.

Dwarven Month

A Dwarven or Short Month is 25 days 2 hours and 48 minutes. It is a period that comes up often in the harmonic lunar cycles, but does not seem to represent any natural observable phenomenon. The Dwarves do not make use of this month; the name appears to relate to its relative brevity and artificiality.

Sidracal Month

The Sidracal Month is the time it takes for the Moon's rising elliptic to move through one sign of the Zodiac. The position of the rising elliptic affects the declination or latitudinal variation of the Moon in the Heavens. The Sidracal Month is 168 days, 6 Synodic Months, or a third of a Long Month. There are 13 Sidracal Months in a Sidracal Year.

Harmonic Month

The Harmonic Month is the time taken for the Auge or Moon's Apogee to move through one sign of the Zodiac. The Auge affects the intensity and timing of tidal flows. The Harmonic Month is 72 days. There are 13 Harmonic Months in a Harmonic Year.

Stellar Month

It takes exactly one Stellar Month for the Moon to pass through the Zodiac. This is almost identical to the Sidereal Month, and the two are often confused. It is approximately 28 days and 93 seconds long.

Years

Western Kingdom Year

The Western Kingdom Year is based on a Sidereal Year of 364 days divided into four Seasons. The first day of each Season is a High day. The middle day of each Season of 91 days is an Equinox or Solstice. After the High day, the remainder of each Season is divided into three Calendar Months of 30 days. In addition, each Season is divided into 13 Weeks of 7 days. Moonday is the first day of each Week and coincides with the Phases of the Moon.

Sidereal Year

The normal Year used by most races is the Sidereal year. This year has 364 days, and exactly encompasses fourteen Sidereal Calendar Months, thirteen Synodic Calendar months, four High days, the Vernal and Autumnal Equinoxes, and one set of four Seasons. It also almost covers one passage of the Sun through the Zodiac and hence fourteen passages of the Moon through the Zodiac. It is also the shortest harmonic cycle for the Synodic and Sidereal Months, and thus sometimes known as a Synodic/Sidereal Year. There are 18 Sidereal Years in a Saros Cycle.

Saros Cycle / Long Year

A Saros Cycle or Elven Long Year is a period of eighteen Sidereal Years, 234 Synodic Months, 245 Anomalistic Months, 252 Sidereal Months, or 255 Draconic Months. It is the minimum period for the various months to resynchronise, and so lunar and solar eclipses repeat based on this cycle. The variable length of Synodic and Sidereal Months also repeats once per Saros cycle.

Sidracal Year

The Sidracal Year is the time it takes for the Moon's rising elliptic to move through the Zodiac. The position of the rising elliptic affects the declination or latitudinal variation of the Moon in the Heavens. The Sidracal Year is 2184 days, six Sidereal Years or seven Ecliptic Years. It is a harmonic cycle for the Synodic, Sidereal and Draconic Months. It is also the shortest harmonic cycle for the Sidereal and Draconic Months, and thus sometimes known as a Sidereal/Draconic Year. There are 3 Sidracal Years in a Saros Cycle.

Harmonic Year

The Harmonic Year is the time taken for the Auge or Moon's Apogee to move through the Zodiac. The Auge affects the intensity and timing of tidal flows. The Harmonic Year is 936 days, three Ecliptic Years, 13 Harmonic Months, 36 Sidereal Months, or 10 seasons and a Sidereal Month. It is a harmonic cycle for the Synodic and Draconic Months. It is also the shortest harmonic cycle for the Sidereal and Anomalistic Months, and thus sometimes known as a Sidereal/Anomalistic Year. There are 7 Harmonic Years in a Saros Cycle.

Resonant Year

The Resonant Year is the period between elliptic lunar crossings occurring at the Auge or perigee. This affects the annularity or totality of an eclipse. The Resonant Year is 655 days with an additional leap day every 5 years, or 26 Dwarven Months. It is also the shortest harmonic cycle for the Anomalistic and Draconic Months, and thus sometimes known as an Anomalistic/Draconic Year. There are 10 Resonant Years in a Saros Cycle.

Asynchronic Year / Long Month

The Asynchronic Year or Elven Long Month is the time taken for the rising ecliptic to move through three Zodiac signs, and the Auge to move through seven in the other direction. The Asynchronic Year is 504 days, 7 Harmonic Months, 18 Synodic Months, or 20 Dwarven Months. It does not represent any known cyclic lunar phenomenon. There are 13 Asynchronic Years in a Saros Cycle.

Ecliptic Year

The Ecliptic Year is the period between Full Moons occurring on the rising elliptic, which is the primary cause of the eclipse cycle. The Ecliptic Year is 312 days, a third of a Harmonic Year, or 12 Sidereal Months. It is also the shortest harmonic cycle for the Synodic and Draconic Months, and thus sometimes known as a Synodic/Draconic Year. There are 21 Ecliptic Years in a Saros Cycle.

Dwarven Year

A Dwarven or Short Year is half an Asynchronic Year, 252 days, 10 Dwarven Months or 9 Synodic Months. It is a regular period that comes up often in the harmonic lunar cycles, but does not seem to represent any natural observable phenomenon. The Dwarves do not make use of this year; the name appears to relate to its relative brevity and artificiality. There are 26 Short Years in a Saros Cycle.

Stellar Year

The Stellar Year is based on the position of the Sun in the Zodiac. The Stellar Year is similar to a Solar Year, but is a little longer due to the precession of the equinoxes, which is to say it takes just over a Solar Year for the Sun to pass through the Zodiac. It is also exactly fourteen passages of the Moon through the Zodiac, making exactly fourteen Stellar Months to the Stellar Year. The Stellar Calendar Year has 364 days, with an extra day every 72 years (these years are known as leap years), and a second extra day every 90 leap years (known as a Great Quarter). The fourth Great Quarter happens a year early, after 25919 Stellar Years, and this completes a Great Year.

The Stellar Year is generally only used by Astrologers.

Synodic/Anomalistic Year

The Synodic/Anomalistic Year is the only lunar harmonic cycle that does not get used in any calendar. It is the period between Full Moons being of the same size (as the position of the Apogee affects the visible size of the Moon). However, as Full Moons don't occur a fixed number of times each Synodic/Anomalistic Year, it is only of academic interest. The Synodic/Anomalistic Year is around 595 days 15 hours. The shortest period between Full Moons of the same size is a Saros Cycle, in which time 11 Synodic/Anomalistic Years will have occurred.

Ages and Aeons

Precession of the Equinoxes

After every Saros Cycle of 18 years, the Moon and Sun return to the same position relative to Alusia, but the Firmament and the stars set within it have moved westwards by 15' or a quarter of a degree. Thus, every 72 years the stars have moves by a full degree. At the end of 360 x 72 or 25,920 years, the Firmament has completed its rotation around Alusia, and the stars return to their original positions, completing an aeon, which the Elves call a Great Year. The precession of the equinoxes refers to the apparent movement of the Sun at the equinoxes relative to the background stars in the zodiac; this is equivalent to the above explanation, and acts as a method of keeping time in the Great Year.

Great Year

The Great Year or Aeon is 25,920 Solar Years. It is the time taken for the Solar and Stellar years to realign, that is, the time taken for the Sun at the Vernal Equinox to pass through the Zodiac, or for the Firmament to revolve once around Alusia. It is ten gross Saros Years, or thirteen Ages.

Astrological Age

An Astrological Age or Great Month is the time taken for the Sun at the Vernal Equinox to pass through one (Elven) Astrological Sign. A Great Month is exactly 1994 years and 308 days, 1440 Long Months, or 110 Long Years and 10 Long Months. An Astrological Age starts when the first star of the constellation is obscured by the Sun, not by the passing of even divisions, so each age varies in length. As it name indicates, Astrological Ages are generally only used by Astrologers. There are thirteen Ages or Great Months in an Aeon or Great Year.

Keeping Track

The Day of the Year

A single glance at the Moon, observing its Phase and the Zodiac sign it lies within, will let anyone with a little training know the exact day of the year. This is due to there being a unique combination of the Phase of the Moon and the Zodiac sign the Moon lies within during any year. The day of the year that this combination occurs will remain the same for almost 1000 years. Another advantage is that an error of up to one day in judging the phase of the Moon is automatically corrected, as the Phase of the Moon currently must be odd on any day that the Moon is in the first half of a Zodiac sign, and even when it lies in the second half. After 997 years (half an Age), the above odd/even rule is reversed, and after another 997 years, the Moon has moved into the next Zodiac sign (due to the precession of the equinoxes), leading to an error of exactly 28 days, or one Synodic Month. At the end of a Great Year, the error is 13 Synodic Months or one year, as the equinoxes have finished a full precession and the calendar is again correct.

This method of telling the day of the year is popular with Elves, who often lose track not just of days but of years. A simple method of instantly knowing the current date is useful and a correction of one Synodic or Lunar month every Great Month (1,994 years) is irritating, but usually acceptable, and can be done easily if the current season is known.

The Passing of Ages

Several methods of tracking Ages are derived from the position of the Sun during the Vernal Equinox, as its declination is zero at that time. Practical considerations disallow the exact measurement of the positions of Stars close to the Sun, as the Sun is somewhat more luminous, even during a rare full Solar Eclipse. However, measurements of positions of stars close to the Moon during Lunar eclipses is more practical, and as the Moon is almost exactly opposite the Sun during the midpoint of the Lunar eclipse, the positions of Stars relative to the Sun can be found. If the correct day of the year is known, then the correction required by the method to return the current date will tell the number of Ages that have passed. Also, the zodiacal name of the first month of the current year (that is, the zodiac sign which the moon lies in for the first and last two days of the first month) will be the name of the Astrological Age. This allows both the day of the year and the current Age to be known within seconds by casual observation of the current season, the phase of the Moon, and the stars it lies amongst; calculating which year you find yourself within the Age still requires careful observation during a lunar eclipse or equinox.