Astronomy - recording the sky

 I'm taking an astronomy class through the local community college. In Kentucky, folks over 65 can get free tuition to take classes at any public college or university - a really cool deal. I've been taking classes since 2018 about a year after I retired. I actually tried this class before, but got very ill in November and had to withdraw. So most of the work so far is a review for me, which means I have more time to digest everything and think about what it means, which is important to me. 

We are on the sixth chapter of the textbook (it's an 8 week class and we are not quite half way through), and I ran across something that this time made me sit up and think and say "whoa!" It was a paragraph about ancient "observatories" used to measure the positions of celestial objects, to keep track of time and date. The pictures used to illustrate this were of Machu Picchu (in Peru) and Stonehenge in England.  [See screen shot below.]

The text noted that the human eye was the only instrument available to observe the visible light of celestial objects - an accurate statement - and that the only permanent record of the observations made was humans writing down or sketching what they saw - a completely inaccurate statement. 

In point of fact, those ancient astronomers, used a far more permanent method of recording their observations than any modern astronomer does - they recorded it in the very stone of their "observatories." Stonehenge is any where from 4,000 to 5,000 years old, and it accurately records precisely the regularities of sunrise, moonrise, equinoxes, solstices observed by those ancient people in the positions of the stone. Moreover, while Stonehenge may be the most famous, it is hardly the only such ancient record in the world.

Modern astronomers record their observations on paper and in computer files all of which are far more fragile than the stone of those ancient observatories. A simple power failure can make our modern records unavailable to us, a powerful EMP could wipe them all out. Our society and its knowledge is far more ephemeral than the knowledge of ancient societies, written in stone and passed from one generation to the next in storytelling and song.  That is a sobering thought.