A view of the landscape of Machu Picchu, a city situated 2 430 m above sea level in the Andes Mountains in modern-day Peru, north-west of Cuzco. The surrounding area is covered in dense bush. It was probably the most astonishing urban creation of the Inca Empire. Photo: PAP/Photoshot
One of the observatories in Machu Picchu - the December Solstice Cave, the so-called Intimachay cave - is located in an area accessible to tourists. The other observatory, the so-called Inkaraqay, is situated in the jungle. Photo: bobistraveling - CC BY 2.0, Wikimedia
Newly discovered geoglyphs in the Peruvian province of Palpa, bordering Nazca. Aerial view of geometric figures and lines, as well as representations of animals and plants. According to 'National Geographic', the lines are from the Paracas and Topará cultures and were drawn between 500 BC and 200 AD. Peru, April 2018 Photo: PAP/DPA, Genry Bautista
An excavation inside the observatory of the sultan, mathematician and astronomer Ulug Beg in Samarkand (present-day Uzbekistan), with the partially preserved arms of his giant sextant. The arcs had an exact meridian position and were faced with polished marble. The light beam of the observed planet passing through two tiny holes fell on the two arcs of the sextant, on which degrees, minutes and seconds were marked. Photo by Igor Pinigin - Own work, CC BY-SA 4.0, Wikimedia
The Ulug Beg observatory (here in 2001) was built in the 1520s. Islamic astronomers worked there, including Al-Kashi, Ali Qushji and Ulug Beg himself. It was destroyed in 1449 and rediscovered in 1908.Photo By Michel Benoist - Own work, CC BY 2.5, Wikimedia
Mechanism from Antikythera (the largest part of it) - an ancient mechanical instrument for calculating the position of celestial bodies. Found in a wreck beside a Greek island between Kíthira and Crete, it dates to 150-100 BC. No mechanism of similar complexity is known until the 18th century clocks. The device in the collection of the National Archaeological Museum of Athens. Photo by Marsyas - Own work, CC BY 2.5, Wikimedia
Presentation of the mechanism from Antikythira - the objects appearing at the top of the display case are holographic, highly magnified images of successive sections of the device, changing every ten seconds or so. Photo Grb16 - Own work, CC BY-SA 3.0, Wikimedia
A diagram of how the mechanism worked: almost 40 bronze gears, driven by a crank on the side, moved several hands. The dial at the front showed the movement of the sun and moon against the background of the zodiac and the Egyptian calendar then in use in Greece, including a leap year every four years. It also showed the phases of the Moon. The dials on the back allowed the synchronisation of the solar and lunar calendars and the prediction of solar and lunar eclipses (Saros cycle). Fig. SkoreKeep - Own work
Machu Picchu and other wonders of archaeoastronomy