It is said that the Celtic peoples attached special significance to the Pleiades at their dawn rising, which coincided with Beltane, or May Day. The Aztecs measured the completion of one fifty-two-year cycle and the begining of the next by the date of culmination of the Pleiades at midnight. Teotihuacan, in central Mexico, antedates the Aztecs by over a thousand years, yet the entire plan of this huge metropolis was based upon the direction of the setting of the Pleiades.
Radiocarbon dating is dependent upon a number of assumptions, however, and one of these was that the amount of radioactive carbon 14 in the atmosphere has been the same for the last several thousand years. We now know that this is not the case. Samples of bristlecone pine have been independently dated by counts of their rings. These dates are systematically older than the radiocarbon dates of the same samples of wood. They show that the amount of radioactive carbon has varied significantly. This variation is linked in turn to the number of primary cosmic ray particles that fall on the earth's upper atmosphere, for these particles are responsible for the production of the carbon-14.
Instead of a steady rain of cosmic ray particles, we now imagine periods of light drizzle and heavy showers. Part of this variation is caused by cyclical changes in the strength of the earth's magnetic field, which controls the activity of the charged particles. Another variation is caused by the sources of the particles. Careful analysis has resolved individual periods of cosmic ray shower intensity, which can be related to specific supernovae, or exploding stars, not too distant from the sun.
In general, radiocarbon dates for European prehistory are systematically too recent, and in fact, the older the radiocarbon date, the more in error it is. When corrections were applied to the radiocarbon dates of Megalithic monuments, the tombs were found to be older, and not younger, than the Mycenaean tholos tombs. The pattern of diffusion from the Mediterranean to Northern and Western Europe had to be abandoned. The Megalith Builders are now recognized as the independent inventors of an impressive pre-Mediterranean culture. The earliest stage of Stonehenge is as old or older than the pyramids of Egypt...
The Pleiades star group, known to European obsrvers as the Seven Sisters, also received considerable attention in Mesoamerica. It found use in the setting of both religious and agricultural calendar dates. In the Aztec Florentine Codex of Central Mexico this group can be identified as Tianquiztli, or the Marketplace; amoung the Maya they were Tzab, the Rattle (of the rattlesnake). The Sherente of Brazil still use the Pleiades to mark the seasons. They say that the year commences in June when the Pleiades first appear as the sun leaves the constellation of Taurus. This is taken to be a sign of wind which ushers in the rainy season. The Navajo dignify the Pleiades by associating them with their principal deity, Black God, creator of fire and light. In fact. a recognizable form of this group appears on the face of Black God.
We tested the baseline for astronomical orientation by determining, for the latitude, building time, and horizon elevations of Teotihuacan, which astronomical bodies could have been viewed along either direction from cross to cross. Of the several possibilities the most likely seems to be the Pleiades. Not only did this conspicuous star group set within 1 degree of the east-west axis of Teotihuacan, but also the group functioned in a most unusual way at that place and tiem. The Pleiades underwent heliacal rising on the same day as the first of the two annual passages of the sun across the zenith a day of great importance in demarcating the seasons. The appearance of the Pleiades may have served to announce the beginning of this important day, when the sun at high noon cast no shadows.
Pisces is shown as two fishes, joined by a cord and accompanied by a wavy symbol that suggests the aquatic attributes of this constellation. Ascending counterclockwise we encounter Aquarius the Water Carrier, who is pouring two wavy streams of water into the mouth of Piscis Australis, the Southern Fish. Capricornus, the Sea Goat, is next and is followed by a centaur-archer, Sagittarius. A scorpion, Scorpius, leads the archer and is in turn led by Libra, the Scales. The next zodiacal constellation is directly across from pisces. It is a woman who holds a spike of wheat, an obvious representation of Virgo. Leo, the Lion, follows, and slightly above him is the Scarab Beetle, which in Egypt took the place of Cancer, the Crab. A man and a woman with joined hands represents Gemini, the Twins. Obvious illustrations of Taurus, the Bull, and Aries, the Ram, complete the set.
Below Leo is situated a cow in a boat with a star between its horns. This figure is Sirius. The jackal near the Hippopotamus is Ursa Minor. Orion is found to be holding a staff and standing near Taurus.
Paleomagnetism of rocks at the bottom of the Atlantic show evidence of reversals of the earth's magnetic field. These shifts occurred periodically and can be dated. The last shift took place about 30,000 years ago, and this is far to early for the reversal which Velikovsky claims happened in 1500 BC.