This page discusses the precessional drift of the constellation Crux, or the Southern Cross, and how it was used as a very high accuracy meridian calibration at a particular time and place in megalithic Europe. The following images allow the details of this unique cosmic circumstance to be visualised.

Figure One: Crux on the meridian; Rennes-le-Château; 1,088BC

In the years centred on 1,088BC, the constellation Crux transitted the meridian upright. That is, both its upper and lower stars (Alpha and Gamma Crucis) crossed the line due south of an observer at exactly the same moment. While this was true for all observers at those locations from which Crux was visible, only for those located at latitude 43° North, (the location of Rennes-le-Château), would this upright transit have been observed immediately above the horizon, as shown in the picture above. Knowledge of this fortuitous circumstance would have made 43° North in 1,088BC an excellent location for high accuracy surveying work, as a simple plumb-bob would permit a nightly confirmation of the precise direction of true south.

Figure Two: Close-up view

Figure Three: The View from Space: looking down on Crux from above the north pole region of the earth; 1,088BC

Animations: A series of short AVI files, created using Redshift:

[Click to view]

Animation One: The precessional twist of Crux:

This short movie shows two thousand years of the precessional drift of Crux compressed into several seconds!. Each frame, taken at 40 year intervals, records the moment when Alpha Crucis transits the meridian on the evening of the spring equinox. The observer is looking towards the south from the city of Cairo. It covers the period from 2,088BC to 88BC. The movie shows clearly how the constellation of Crux descends slowly southwards in the sky, and at the same time also rotates counterclockwise, so that, as can easily be seen, in the period centred on 1,088BC, it transits perfectly upright.

Animation Two: Crux on the meridian; Rennes-le-Chateau, 1,088BC

This movie compresses an evening of the nightsky into several seconds, and shows the transit of Crux above the southern horizon.

Animation Three: Crux on the meridian; Stonehenge; 2,900BC

Taken nearly two thousand years before the Animation Two, the constellation is seen to be tilted to the right at the transit of Alpha Crucis, and was just above the horizon from the latitude of Stonehenge.

Animation Four: Crux on the meridian; Athens; 300BC

Nearly eight hundred years after the upright transits of 1,088BC, Crux tilted to the left at the transit of Alpha Crucis, and was visible just above the horizon from the latitudes of Greece,.

Animation Five: Crux on the meridian; Jerusalem, 33AD

The view south at the Crucifixion.

Animation Six: The Square of Pegasus on the meridian, Rennes-le-Chateau; 1,088BC

The other constellation used for accurate meridian calibration also had its perfectly upright year in 1,088 BC also, as shown in this movie. Located opposite Crux in the heavens, it moved in opposite directions due to precession, drifting northwards and twisting clockwise.

Animation Seven: The Procession of Constellations, from Orion to Crux; Giza, Egypt; 2,900BC

This movie takes a little longer to load, but is worth the wait. It shows the view looking towards the south from Egyptians latitudes in the years around 2,900BC. It displays the procession of constellations which are led out by Taurus. It is interesting to observe the relationship between the great Boat or Ship of Vela and the horizon, and to see how Crux, far from being an unconnected element in the Egyptian star-mythology, is actually part of the same constellation-complex as Orion/Osiris and Sirius/Isis.