Jupiter’s mean synodic period repeats after slightly less than 399-days.  A synodic period completes when an observer sees the celestial sky return to the previous state.  Jupiter moves into each of 12 constellations approximately every 34-days.  Our own faster 365.25-day revolution about the sun overtakes Jupiter by slightly more than a month year after year.

399-Day Mean Synodic Period of Jupiter

Jupiter’s mean synodic period repeats after slightly less than 399-days.  Recall that the synodic period completes when an observer sees the celestial sky return to the previous state.  Jupiter’s actual orbit is slightly less than 12-years or 11.86-solar-years.  Jupiter moves into each of 12 constellations approximately every 34-days.  For example, Jupiter's heliacal rising occurring in the constellation Leo is followed 399-days (≈ 398.88-days) later by the next heliacal rising in the constellation Virgo.  Our own faster 365.25-day revolution about the sun overtakes Jupiter by slightly more than a month year after year.  Jupiter seems to shift an entire constellation toward the east from its previous place.  Jupiter continues this trek near to the ecliptic plane for 391 heliacal risings altogether.  The earth, sun, and Jupiter are now again in the same relative positions as at the beginning of the cycle and the entire cycle repeats.


Jupiter’s close attachment to significant, round calendar values and magnificent brilliance makes the planet an easy candidate for ancient worship.  Wandering stars or planets were highly praised major deities.  A visible giant among the planets, Jupiter is eleven times larger than earth.  The brightest stars (planets in this case) were the most influential, an idea carried forth into modern astrology.  Babylonian mythology assigns Jupiter the planetary god role of Marduk.  Babylonian Marduk was the acknowledged the “king of the gods”.  The Greeks referred to Jupiter as Zeus.  Romans worshiped Jove and Jupiter names interchangeably.  Jupiter and Zeus shared similar characteristics through later cultural borrowing.  They were equal counterparts in the imaginary celestial hierarchy.

The story of Marduk is a Creation story very similar to the Bible’s own.  The myth evidently stems from the Old Babylonian Empire, about 1800 B.C.E.  Marduk is sovereign deity over the heavens.  Marduk institutes order by killing the dragon of primordial chaos, Tiamat.  Marduk then creates the sky (firmament of heaven, Genesis 1:8) and the sea (firmament of waters, Genesis 1:7) from the monster's remains.  He establishes the year and divides the length into 12-months.  Marduk assigns the other constellation gods to their stars and planets.  Marduk decides that Jupiter’s path along the ecliptic will guide the stars.  The Babylonian Creation Epic, Enuma Elish further mentions Marduk had 50 names associated with 50 special powers.  Jupiter traditionally marks a 12-year pattern that repeats the stellar configuration almost exactly every 12-years.  Babylonian scribes knew that Jupiter opposes the sun (opposition) according to a nearly 12-year cycle.  They added intercalary days to plot Jupiter’s position for a zigzag effect in the astronomical diaries.  Marduk also determines the horizon and zenith.  He furnishes the sun’s rising and setting positions and places the moon to light the night and count the days (Genesis 1:14).  Marduk, Zeus, Jove or Jupiter was the designated ruler in the night sky.

Ancient calendar makers keenly sought time multiples in celestial operations.  They choose references that provided lesser denominations and particularly those offering the closest approximations to whole number integers.  Jupiter’s synodic period influenced early mythology and the Antediluvian Calendar.  Jupiter’s synodic period between superior conjunctions rounds off to 399-days and rounding further, 400-days.  Both Jupiter and Venus share mythological roles in ancient astronomy.  Numerical matching themes of 364-day-Ethiopic-years enable 399-days to match with 399-years.  Squaring 20-year-l/s-Katun-cycles to make one Mayan 400-year-Baktun-cycle circumscribes the Mayan 104-year Venus Round.  The Judaic 105-year Venus Round seen for Seth is a variant stemming from the numerical matching concept.  The Egyptian Calendar likewise incorporates mythology.  Hathor was the son of Isis/Osirus and refers to planet Jupiter.  Moving at the rate of about one constellation per year, a 12-year path near the ecliptic was evident for 4,332.6-days (sidereal orbit).  The deity Hathor was commander for the 400-year timekeeping instrument of the ancient Egyptian Calendar.  Jupiter’s time estimate of a 399-day synodic period spiritually aligns with 399-years and naturally conforms to the 400-day and year numerical matching theme so prevalent in ancient calendars.  One year 360-day difference equals 36 decan stars of legend having 10-days or 10-degrees of separation between them.

Returning to a 364-day-Ethiopic-year, where the last day of a 365-day-solar-year numerically matches the same number of years, the synodic period of Jupiter exceeds by 35-days.  The only difference is 1-day, so Jupiter appeared one constellation easterly after 1-Ethiopic-year, plus 35-days.  Consistency in ancient calendar numbering systems suggests the early view that Jupiter had a 400-day synodic period.  The planetary god numerically matches 400-year integer multiples pertaining to synodic movements through the zodiac.  Numerical matching of X-day with X-years allows extrapolation.  Jupiter was instrumental to the 400-year-Baktun-cycle known to the Mayans.  Since two 400-year-Baktun-cycles comprise one 800-year Generation Cycle, we can substitute earlier statements with more detail.  One Mayan 104-year Venus Round happens in 400-years and two Mayan 104-year Venus Rounds occur for every 800-year Generation Cycle.  Genesis 5:6 lists Seth’s primary 105-year age for the Antediluvian Calendar of the Patriarchs.  The Judaic variant 105-year Venus Round is the primary age of Seth.

Are you a pastor, educator or a student of the Holy Bible?  Timeemits.com seeks anointed people to review and contribute to the Ages_of_Adam ministry.  Ancient lunar/solar calendars like the Jewish and Mayan calendars provide the background to understanding early time.  Ancient calendars of the Holy Bible use differences between the moon and sun, numerical matching and a 364-day calendar year to describe X-number of days that match with X-number of years.  Ages_of_Adam is a free read at timeemits.

Clark Nelson is webmaster for http://www.timeemits.com/Get_More_Time.htm, author of Ages_of_Adam and sequel, Holy_of_Holies.  Copyright 2006  Clark Nelson and timeemits.com  All Rights Reserved. URL http://www.timeemits.com/HoH_Articles/399-Day_Mean_Synodic_Period_of_Jupiter.htm

Jupiter, synodic, constellation, wandering stars, planets, gods, Ethiopic, Mayan, Marduk, creation, Genesis, Venus, generation, cycle, mythology, Seth, patriarchs