can hardly be noticed in a lifetime, making a shift of only one degree in 70 years.

Movement of the Earth’s axis

The effect of precession can be noticed in three ways. One: the pole shifts through the circle of circumpolar stars. Two: the constellations beyond the sun at its rising position at the vernal and autumnal equinoctial points change over this long period. Three: the rising and setting points of the stars themselves slowly shift along the horizon. Stars that had once been outside the field of view as seen from a specific point on Earth would eventually move into sight again after some time.

Shift of the vernal equinox through the constellations due to precession

Owing to the slow northward motion of the vault of the sky caused by precession,in around 9,400 BC, a viewer who stood on the south coast of Malta and looked in a southerly direction would behold an unusual sight. A star appeared in the sky of a brilliance never seen before. It was Sirius.

For viewers at Malta’s latitude, Sirius had been invisible for five thousand years before that date. Now it came into view again in all its splendour, and over the years the time of its visibility in the night sky grew gradually longer.

Sirius rising, as seen from Malta at around 9,150 BC

The ideal location from which to watch this delightful phenomenon was the site now called Ħaġar Qim. And it was precisely here that the very first temple, an observatory to the star Sirius, was built. This is the ruin