Nowadays most of us do not look at the sky. Once upon a time, it was not so. People did look at the sky, and the sky appeared much more brilliant and densely populated than it does today. The main problem today is light pollution: the ubiquitous presence of artificial light. So, if we want to see the sky as it was before the spread of large-scale electric illumination, we have to go to very special places: mountain summits or, even better, mountain highlands with a high horizon all around. In this case, we can realize that the ancient sky was an overwhelming, dominant presence at night. Thousands of stars could be seen, and a celestial river flowing with the very same velocity of each star turnaround occupied a wide band all along the firmament: our galaxy, the Milky Way. But, why and when did people start to look at the sky? The answer is far from simple. The great Roman poet Virgil once wrote that humans became really human only when they started counting the stars in the sky, and perhaps he was right. People defined “anatomically modern humans”, that is, Homo Sapiens, as we are, are attested to in Africa from around 200 000 years ago. Their intellectual behaviour, however, underwent a profound change at the beginning of the period defined as Upper Palaeolithic, around 50 000 BC. Archaeological records show two fundamental innovations: first, a geographical expansion, which led them to move from Africa and to settle in Europe. Europe was at that time inhabited by another human species, the Neanderthals, who rapidly extinguished for yet unclear reasons. Second, an explosion of technical and artistic skills and in particular, of painting, with the masterpieces of world-famous cave-art sites. The most ancient known, the Chauvet cave in south-eastern France, is dated to around 30 000 BC. It is likely that also astronomy – or if you prefer accurate sky watching - was born in this period. For instance, series of notches on incised bones have been interpreted as possible calendrical marks connected with a lunar count and depictions of cave art have been interpreted as possible representations of constellations The Upper Palaeolithic people lived of hunting and gathering. It is important to stress that it was not a “primitive” life: hunting required rather sophisticated techniques and gathering required appropriate knowledge of the natural cycles and of vast portions of lands. This period formally ends with the birth of agriculture and sedentarism, a complex process – not well understood yet – which brings sometimes the name of “Neolithic revolution”. Since not many years ago, this process was viewed as an important improvement of human life. But nowadays it is not so obvious that agriculture was a real improvement, and in any case - for what matters here - we know that people started to build huge structures before: at Gobekli Tepe, in south-eastern Turkey. Here, some 12 000 years ago and therefore before the introduction of agriculture, elaborate architectural projects were devised, with the construction of stone enclosures endowed with huge, T-shaped megaliths, usually finely engraved – mostly with figures of animals. There are some hints that astronomy was already present in these structures. In any case, with the later explosion of megalithic cultures in the Mediterranean, its presence becomes well attested. The oldest megalithic structures of the Mediterranean are passage graves, like Kerkado, Carnac, dated to about 4 800 BC, and stone circles, like the oval of Almendres, Portugal: all passage graves face the Sun as it rises or climbs in the sky. All stone circles in Portugal are orientated very close to due east and the Sun rising at the equinoxes. In the middle of the 4th millennium BC megalithic architecture appears also in Malta. Here, a mother Goddess was venerated and the plan of the temples devoted to the Goddess repeats obsessively her opulent image. So these monuments are a sort of giant replicas of the divinity and all of them are oriented astronomically, although to different targets. Perhaps the most spectacular is Mnajdra Temple 2. The axis here runs straight east-west up to the west wall, where a central altar is to be found. To the left and right of the altar there are two similar monolithic slabs. A light-and-shadow effect occurs at the two solstices, when the Sun projects a flag-like figure on the two slabs, respectively. At the equinoxes, the sun rises in alignment with the central axis. So over the course of the seasons, one can therefore follow the movement of the Sun at the horizon by observing the sunlight that enters the temple day after day.
