Three types of years:
Solar Year: The time it takes for the earth to revolve around the sun. 365.24 days
Lunar year: The time requires for 12 complete cycles of the moon. 354.3 days
Draconic Year: Time when the earth, moon and sun realign on an elliptic plane. 346.6 days
By extraordinary Cosmic arrangement, these years align with each other in varied and fairly precise arrangements, allowing for the science of eclipse prediction. This arrangement is most clearly visible in the Metonic Cycle.
Metonic cycle: a period of 19 years (235 lunar months), after which the new and full moons return to the same days of the year. For example, if you have a new moon on June 1st, then in 19 years you should usually have a new moon on June 1st too, with this date varying over the course of decades and centuries ( at some point it becomes June 2nd etc...) due to the slight offsets of calendar time and orbital reality.
In the Metonic cycle (approximately 6,940 days)...the Solar, Lunar and Draconic years align. Basis of the ancient Greek calendar ( and modern Bahai faith) and is still used for calculating movable feasts such as Easter. Eclipses can then repeat on basically the same day of the year every 19 years, though over time the date moves forward. It's relevant to eclipse cosmic timekeeping. For example, the time frame we will be most concerned with begins with a solar eclipse on the Spring Equinox March 20th, 2015 and ends with a solar eclipse on the Spring Equinox on March 20th, 2034.
There is no scientific reason these different cosmic years should align, and it is generally dismissed as a "coincidence"
Eclipses are most easily predicted through the Saros Cycle, which helps defines eclipses as individual personalities. Saros cycles are born as partial eclipses, mature into total eclipses, fade as partials and eventually die. They bear numbers for names, like 136 and 145.
A Saros Cycle is a period of exactly 223 lunar months, approximately 18 years and 11 days, used to predict eclipses. One Saros period after an eclipse, the Sun, Earth and Moon return to about the same relative geometry, a near straight line, and a nearly identical eclipse will occur, but at a different place on earth. A Saros Cycle is 19 eclipse years. There are about 40 Saros cycles currently occurring, about 26 of which are creating complete (total and annular ) solar eclipses. So we will meet about 26 personalities of various histories.
"An eclipse is a relatively rare coincidence of several factors at once in order to make the shadows line up properly. First of all, it must be a new moon for a solar eclipse or a full moon for a lunar one, so the Sun, Moon and Earth lie in a straight line. Secondly, these 3 bodies must line up "vertically" so the eclipse shadows aren't too far north or south to be seen from Earth. This means the Sun and Moon must be "near" one of the Moon's Nodes, where the paths of the Sun and Moon cross. ("Near" is roughly an 18 degree orb.) Finally, the difference between a total eclipse of the Sun and an annular eclipse is in how far apart the Moon and Earth are. At the "perigee" point, when they are closest together, the Moon's umbral shadow (the dark part of the shadow, where totality occurs) can reach all the way to the Earth's surface and form a total eclipse. At the "apogee" point, on the other hand, when the Moon is farthest from the Earth, the tip of the Moon's umbral shadow dangles thousands of kilometers above the Earth's surface, never touching, and we see only an annular eclipse.
So to predict future eclipses, we need to understand 3 interlocking cycles, namely:
By "coincidence", these cycles all repeat nearly exactly every 18+ years. This is because:
This period of 6585.322 days is called a "Saros Cycle" (named from a Greek word meaning "to repeat"). This is roughly 18 years, 11 days and 8 hours (depending upon how many leap days there are on the calendar). So if there's an eclipse now, in 6585.322 days from now,
In short, all the factors that make an eclipse happen now will repeat (with surprising accuracy!) exactly one Saros cycle from now and another eclipse (of very similar geometry) will happen then."
(From Wiki Calendar
eclipses also happen to come in tribes, which we see in the little considered Hepton Cycle:
Hepton Cycle: Hepton means 7-sided. The Hepton Cycle is a pattern of 7 eclipses occurring within an almost 20 solar year period ( a 21 eclipse year period)- each eclipse occurring on the same day of the week ( the day of the week currently is Monday). It is a coordination of 41 lunar months and 7 eclipse years.
Hepton eclipses are spaced at 1211 day intervals.
1211 days is 7 eclipse seasons or 3 and 1/2 eclipse years.
An eclipse season is 173 days. An eclipse year is 346 days.
The Hepton forms time patterns of 7's. 7 eclipse seasons (3 and 1/2 years) and 7 eclipse years.The Hepton is not at work in all total solar eclipses, but about one fourth of them.
The 7 Hepton eclipses within the 21 eclipse year time frame form a nucleus of relation to other solar eclipses within the time frame. Hepton cycles overlap at beginning and end.The Hepton Cycle was first named by western science in the 1950's but was apparently known to Mayan astronomers.
Cosmic Timekeeping: The reflection of these Eclipse cycles in a consideration of history.
There are three main kinds of years. The solar year (which has a couple slight variations), the lunar year (which is cultural more than scientific but still maintains an ecliptic reality) and ,finally, the draconic (eclipse) year.
They depend on your point of reference, your perspective.
The solar year is the time it takes for the earth to revolve around the sun (365.25 days).
The lunar year is the time to complete twelve full cycles of the moon (355 days).
The Draconic Year is the cosmic perspective of timekeeping, the realignment of earth, moon and sun on an ecliptic plane. It is the eclipse year. It has 346.6 days in it.
By what some call extraordinary coincidence., all these completely unrelated years match in the Metonic Cycle every 19 years. Meaning you willthe same phase of the moon on a given date every 19 solar years. Eclipses also return on dates in a similar fashion, as we will see, There is no scientific reason for this alignment of different cosmic timekeeping, just as there is no scientific reason for the sun/moon alignment.
The Draconic year is the time taken for the Sun (as seen from the Earth) to complete one revolution with respect to the same lunar node (a point where the Moon's orbit intersects the ecliptic). This period is associated with eclipses: these occur only when both the Sun and the Moon are near these nodes; so eclipses occur within about a month of every half eclipse year.
There are two eclipse seasons every eclipse year. The average duration of the eclipse year is 346.62 days). The term “draconic” is connected with an idea of the ancients, according to which the sun and moon are devoured by a dragon during an eclipse.
The moon’s draconic period of revolution (the so-called draconic month) has important significance in the theory of solar and lunar eclipses. Since a Draconic Year is 346.6 days long. 7 Draconic Years equals 2422 days, half of which is 1211 days, or the time between "eclipse seasons". These two figures reappear regularly in the patterns we will explore on this website.
An eclipse season is one of only two periods during each year when eclipses can occur, due to variations in the angle of the moon in relation to the sun.. Each season lasts about 35 days and repeats just short of six months later, thus two full eclipse seasons always occur each year. That does not mean there are always eclipses during that time. Within a year that has eclipse, they often occur 177 days apart.
There are 40 to 41 different Saros Cycle Eclipses returning at any given moment in history. Each is different. Above, the various eclipses of a single Saros member( Saros cycle 136)painted one at a time every 18 years on the face of earth. The individual eclipse keeps returning to different locations in that timely fashion for more than a thousand years. It begins its eclipse life as a partial eclipse, gradually becomes a Ring of fire eclipse, turns into a a hybrid, and eventually matures into a series of total solar eclipses. Finally it fades in the same fashion until the cycle eventually dies. It mimics life and follows the idea of maximum Expression. Due to the elliptical nature of the orbits of Earth and the Moon, the exact duration and number of eclipses in a complete Saros is not constant. A series may last 1226 to 1550 years and is comprised of 69 to 87 eclipses, of which about 40 to 60 are central (i.e., total, hybrid or annular)
Here is Saros 136 over the course of about 160 years. Because of orbital realities, the Saros changes where its landing occurs on earth every 18 years. . There's a shifting regularity to the pattern. This is what makes eclipse prediction possible. You will notice the Aug 2nd 2027 Mideast Judgment in the top center of this illustration, basically in the middle of earth, with the center of the line, the Maximum Eclipse, at the Valley of the Kings in Luxor, Egypt.
Within the forty to forty one ongoing Saros solar eclipses, a pattern emerges of some eclipses occurring exactly 7 eclipse years apart from each other. That is 2422 days. Within that pattern, eclipses are spaced 7 eclipse seasons (1211 days) apart as well.
This is the Hepton Cycle.
Above, the extraordinary interaction of two Hepton eclipses- both occurring on Mondays- spaced 2422 days apart intersecting over the United States. The Hepton Cycle has been so little considered that there does not appear to be a single image illustrating its properties on the internet. It is described briefly in a few scientific documents and was apparently known to Mayan Astronomers..
The Hepton Cycle can be used for predicting series of solar eclipses with some 13 or 14 members which alternate in visibility between the northern and the southern hemisphere. The name was introduced by George van den Bergh (1951) and reflects its length of duration (i.e. seven eclipse seasons---3 and 1/2 years.). It is also 41 lunations long. Some members of a Hepton Cycle repeat on the same day of the week. This trait is visible in the Eclipse Judgments, where 7 significant eclipses spaced 1211 days apart all occur on a Monday, or Moon day, as of course, it refers to. it has been little considered likely because its leaves out many of the members of the various Saros. I will attempt to consider all the eclipse over a 22 year time frame, whether obviously related to the Hepton or not.