Because the period from one vernal equinox to the next is shorter than the stellar year, the star position of the equinox changes by about one degree every 72 years. In about 25,920 years this point marking the beginning of spring will have made a full circle around the zodiac.
Evidence of an early, probably Neolithic people who marked important events not by conventional calendars but by associated astronomical configurations is a major thesis of books like Hamlet's Mill.
Austronesians appear to have been one such type of people. We don't know if Austronesians ever had calendar counts, but if they did these must have been assigned to the recondite knowledge used by initiates only. However, we do know that they often marked events, including those found in their mythologies, with heavenly conjunctions or other phenomenon. For example, the Hawaiian legend of the explorer Hawai`i-loa who noticed a conjunction of the Pleiades and Aldebaran with Jupiter and steered toward these stars to discover Polynesia.
In this case, we see that the stars indicate both place, as directional bearings, and time, by means of the timing of the stellar conjunction.
Babylonian astronomy might preserve something of a similar sort from the Sumerians with regard to the location of our cosmic volcanoes. Mesopotamian seals often contain depictions of astronomical configurations in scenes of significant mythological events.
The star known as Nibiru (also Neberu, Nebiru) to the Mesopotomians has more than one identification by researchers in this field. The one that is of interest for us is Nibiru's identification with Jupiter. In the cosmological Enuma elish (7.124ff), Nibiru is one of the fifty names given to Jupiter, the planet of Marduk:
Nebiru shall hold the crossings of heaven and earth;
Those who failed of crossing above and below,
Ever of him shall inquire.
Nebiru is the star which in the skies is brilliant.
Verily, he governs their turnings, to him indeed they look
Saying: "He who the midst of the Sea restlessly crosses,
Let 'Crossing' be his name who controls its midst.
May they uphold the course of the stars of heaven;
May he shepherd all the gods like sheep.
From the quote above, it would appear that Nebiru is connected in some way with crossings over the sea. In fact, the name "Nebiru" is derived from eberu, "to cross," and actually means "ferry, ferryman, ford." The authors of Hamlet's Mill connect Nibiru with Urshanabi the ferryman to Paradise in the epic of Gilgamesh.
What is particularly interesting about Nibiru is that the planet's "point" or "station" is used by the Babylonians, and also likely by their predecessors, to construct celestial maps. The following quote refers to Jupiter/Marduk measuring the universe:
He determined the year by designating the zones:
He set up three constellations for each of the twelve months.
After defining the days of the year (by means) of (heavenly) figures,
He founded the station of Nebiru to determine their (heavenly) bands,
That none might transgress or fall short.
Alongside he set up the stations of Enlil and Ea.
The 'heavenly bands' constructed with the "station of Nebiru" as the reference point are known as the paths of Anu, Enlil and Ea.
According to authorities on Babylonian astronomy referenced in Hamlet's Mill, the path of Anu is parallel to the celestial equator and extends to a point about 15 to 17 degrees north and south of our own equator. The path of Enlil is a band of similar width north of the path of Anu, while the path of Ea is the southern zone of equal measure.
The latitude of 15-17 degrees North, of course, would fit well with both Mt. Pinatubo and Mt. Arayat. The question is though whether this station of Nebiru, obviously a fixed star or constellation used to build the entire planisphere of the Babylonians, was north or south of the equator.
According to researcher F. M. Th. Bohl, the station of Nebiru was the point of entry of Jupiter into the path of Anu observed during the night of the vernal equinox, the Babylonian New Year.
During this period, the equinox occured when the sun entered the constellation I-Iku which is identified either with the square of Pegasus or some location in the Aries group.
In either case, a night observation of Jupiter with that planet entering an area corresponding to the geocentric latitudes (declination) of 15 to 17 degrees would point to the constellation Virgo. I would suggest the star Spica, or alpha Virginis.
Indeed, researchers Paul Neugabauer and Albert Schott following the work of Günter Martiny, have suggested that Neo-Babylonian (Assyrian) temples were oriented toward the azimuth intersecting Spica and the vernal equinox at the horizon. Of the three, Neugebauer gave up on the idea when he could not find any evidence that Spica was an important star in Babylonian astronomy.
However, I would suggest that Spica was indeed the station of Nibiru, the point used to demarcate the boundary of the paths of Enlil and Anu, and by similar proportion also the path of Ea.
During 3102 BC, the date of the beginning of the modern era in the Hindu calendar, Spica was located directly above about 15.48 degrees North latitude. The position was not much different at the beginning of the Mayan calendar according to the estimate that places that date in the year 3114 BC.
Thus, Spica would have been an excellent zenith star for navigators seeking the sacred volcanoes. It would have been very nearly directly overhead at its highest point in the sky. As such, Spica would also have acted as a bearing star since it would be directly to the east when rising and to the west when setting, if the observer is at the corresponding latitude.
With Nibiru as the ferry-person to Paradise from the "confluence of the rivers," it would be logical that his station would be guiding star to that very location, at a time when the Pleiades marked the point of the spring equinox.
Spica is also widely thought to be the starting point of the lunar mansions of the Chinese zodiac. Among Pacific Islanders, Spica is often paired with Arcturus, the zenith star of the island of Hawai'i, by traditional navigators to determine latitude using the different rising/setting times, if any, of both stars.
If we combine this conjecture, with the earlier one made regarding the meridian of Yamakoti, then we get surprisingly accurate coordinates for the ancient axis mundi. Of course, the longitude given by the Hindu astronomical texts depends on whether one identifies "Romaka-pura" as Alexandria or Rome. There is good reason to think it is the former.
According to the astronomer Varahamihira, the Romaka Siddhanta, written in Romakapura, has a year length nearly exactly that used by Ptolemy and Hipparchus. There are also rather close values to Ptolemy's anomaly of the equation of center, and for that astronomer's revolution length of the Moon's nodes. This would indicate that the Romaka Siddhanta borrowed largely from the astronomical work carried out in Alexandria, and specifically by Ptolemy. Yamakoti, or "Yama's Peak" would in this case be the location of the Underworld kingdom where both the good and bad go after death. The same symbolic location within Mt. Mashu traveled to by Gilgamesh.
With Romakapura as Alexandria, the corresponding meridian of Yamakoti to the east of Lanka, which Indian astronomers equate with Avanti (75.76E), would be at about 121.64 degrees East, a bit more than the longitude of Pinatubo.
Varahamihira's Quadrants (Romaka = Alexandria)
Lanka (75.76E) - Romaka (29.88E) = 45.88 degrees
Lanka (75.76E) + 45.88 = 121.64E degrees (meridian of Yama's Peak)
Paul Kekai Manansala