How do ancient astronomical observatories function?
Think of the ancient observatories as calculators or computers. Stones, slits in rock, lines of stones, carved notches, all these were done in such a way as to line up with each other on specific days of the year – the equinoxes and the solstices were very important to the ancients, as these were specific days that could be counted on as milestones in the year. The observatories let them know when it was the solstice or the equinox. Some would also align to Sirius rising on a specific day (Sirius was important to Egyptian culture, as its rising in the spring signaled that the annual Nile flood was imminent). In ancient times, the ability to predict an eclipse or the change of seasons was the precinct of a priest class – these people had power and prestige and so needed monuments and great works to prove to the people that they were important people to be feared and respected. In some cultures the equinoxes and solstices were religious events, so the priests had to know when they occure
