The earliest finds, on which there are astronomical records on bone fragments, date back as far as 20,000 years. Later, more developed peoples began to benefit from it in relation to agriculture, following the alternation of day and night and the periodic renewal of the seasons in order to ensure excellent harvests. In navigation, too, astronomy guided countless peoples along the sea, who used the stars to find their desired destination. However, the earliest written documents ascertaining a systematic study of phenomena were found in Mesopotamia: clay tablets, engraved with cuneiform characters, on which were engraved the motion of planets, the presence of comets, the occurrence of eclipses. In short, a veritable astronomical diary. However, these explorers of the universe conceived of the heavens primarily in religious terms; they worshipped the home of the gods, and they believed that those were signals sent to influence the lives of individuals. Comets for example were seen as omens of doom, and astronomy therefore had a very thin divide with astrology. The sky was scrutinized by astronomer-soothsayers, whose job was to accumulate data for calendars and guard legends that had the sky as their setting. Among the earliest peoples of whom we have records are the ACCADIANS, dating from a region where Babylon would later arise 4500 years later. The Babylonians are credited with handing down countless discoveries, as are the Egyptians, who are still regarded as very influential peoples through their surveys on the banks of the Nile. To this day we still do not know whether the pyramids had a close connection with the sky, despite various theories that would liken the pyramids of Giza to the belt of the constellation Orion, but there are other megaliths that would be with certainty specially erected constructions thanks to astronomical observations. All over the world there are many megaliths, sometimes of considerable size, bequeathed to us by our ancestors. One of the most impressive and mysterious is undoubtedly Stonehenge, the "stone enclosure" in southern England, 1 km from the village of Amesbury. It is thought to have been an ancient astronomical observatory, since its axis is built in such a way as to be oriented in the direction of sunrise on summer solstices. It was the Greeks who made the studies scientific, however, because they were the first to ask why such phenomena occurred and tried to give an answer in mathematical terms. Among the astronomers-philosophers of the Greek era we find names such as Thales, who was able to determine the apparent diameters of the Moon and the Sun with good approximation; but also Philolaus, Aristotle, Aristarchus, Eratosthenes and Ptolemy, each of whom contributed theories and scientific discoveries, some of them relevant. For Ptolemy, the Earth was at the center of the Universe, and around 140 A.D. he drew up the most accomplished astronomical synthesis of its time, which has gone down in history as the "Almagest." Central America was also a cradle of civilizations devoted to the study of astronomy. Very relevant to this day are the Mayan predictions and calendars, a people who were extremely attentive to the study of the heavens and who are still making waves today, while the Arabs, after the conquest of the Mediterranean countries, are credited with helping to keep an astronomical culture flourishing, so much so that a good part of the names of the stars are precisely of Arab origin. It was thanks to Copernicus, a Polish cleric, that it was realized that the Earth revolved around the Sun, thanks to his main work "De revolutionibus orbium coelestium." A work that clearly met with stiff opposition from the clergy who claimed that God had placed the Earth at the center of the Universe.
Despite the validity of that publication, it was only through later observations that its true veracity could be attributed and accosted with the success it deserved. These observations were conducted by the Danish astronomer Tycho Brahe, who having observed a supernova explosion, visible that night even to the naked eye in the constellation Cassiopeia, destroyed the Ptolemaic conception that the outermost part of the celestial sphere was immutable. The story goes that the astronomer that night, astonished by that observation, asked his neighbor to give him a shot to see if he was awake. The same astronomer then passed data from decades of observations to John Kepler, initially his assistant and later successor, who analyzed them and formulated the three laws of motion of the planets. Although the earliest types of telescopes could date back as far as the Assyrians, it was in 1609 that Hans Lippershey, a Flemish optician, developed the first true telescope, with which Galileo Galilei, after improving it, began the first real observations of the universe with an instrument. Galilei made great discoveries: from Jupiter's 4 main satellites to the lunar mountains, and published it all in "Sidereus Nuncius." Again the inquisition carried on a "war" because his discoveries were against the knowledge of the time. One of the greatest minds in history, Isaac
Isaac Newton
Newton, was the originator of countless discoveries in the field, including universal gravitation, fluid motion, the decomposition of light, and much more. In those days, telescopes were beginning to be perfected and observations thus became increasingly reliable. Among the owners of the largest telescopes we find Sir William Herschel, who in 1875 built a telescope 12 m long and 1.2 m wide, thanks to a grant obtained from the King of England. It was an exceptional instrument for the time, with which he devoted himself to systematic sounding of the sky. A few years earlier he was the author of the discovery of Uranus and a few double stars. During his systematic observations he also compiled a few catalogs of nebulae and star clusters. Herschel was succeeded by many other scientists of world caliber who are part of the history of astronomy, such as the various Huygens, Cassini, Omer, Halley, Bradley, Messier, Lagrange, Laplace, Fraunhofer, Bessel, Kant, Wolf, Galle, Le Verrier, Hertzsprung, Russel, Einstein, and Hubble. Although for some of them (such as Einstein's relativity, Hubble's constant, Messier's catalog, the H-R diagram, Halley's comet, Cassini's splitting of Saturn's rings, sunspots) it is enough simply to pronounce the name to associate the relevant discovery, to describe every single insight of each of these great researchers would be impossible in this context, but we can say with certainty that each of these brilliant minds has contributed to our knowledge, and much of everything we know today we certainly owe to them.
Today we peer into the universe with the giant telescopes of the largest observatories, and even with space telescopes, which probe the remotest known universe. But we cannot forget what we have been, and how we got there. To look at the sky is to look into the past. When we look up at the firmament, let us remember those who spent their entire lives contemplating, studying and even worshipping that free spectacle we now call the universe.
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