Wednesday, June 17, 2020

Ancient Moon Shadows

Is everyone ready for the Annular Solar Eclipse this Sunday, June 21st?  Charted a viewing spot? Got your glasses? Tracked the path of totality and calculated obscuration?

Now imagine that if you didn't fully prepare and estimate those facts accurately, you could be beheaded. Not a typo. Beheaded. Because history is wild. 

On October 22, 2136 BC, astronomers in China noted what is now the oldest surviving record of a total solar eclipse, which occurs when the moon passes between the Earth and the sun, causing the moon's shadow to fall upon Earth and block the sun from view.

In ancient China, astronomy was a government-mandated pursuit, and state astronomers had quite sophisticated observatories for their time. Good thing too, for observing solar and lunar eclipses, as well as tracking planetary orbits, were divination tools for predicting the fate of the Emperor.

If an Emperor could predict a solar eclipse, such was a good omen for his health; accuracy was helpful in validating that he was the ordained link between heaven and his subjects on Earth, endorsing his divine right to rule. Imprecise predictions could be seen as evil omens, or even result in a new ruler, whereby rivals for power might use the eclipse as a sign that they could overthrow one who had lost the blessing of the gods. Careful records were made of all solar eclipses. (Lunar eclipses were only haphazardly noted, being so common as to merit lesser import.)

Solar Eclipse
As early as 2650 BC, a star-gazer named Li Shu wrote about celestial bodies, in particular noting that the sun, earth, and moon moved in harmonious ways. Technology in ensuing years revolved around trying to forecast when certain events might occur so as to keep their political successions and societies more stable.

The fascinating field of "Archaeoastronomy" shed light on the Oracle Bones of the Shang Dynasty (1600 – 1050 BC), unearthed in Anyang, Henan Province. Hailed as the bones of dragons (though actually turtles or oxen), they represent some of the earliest Chinese writings. One such gem tells us that the failure to correctly predict the timing of a total solar eclipse resulted in beheadings:
"Here lie the bodies of Ho and Hi,
Whose fate, though sad, is risible;
Being slain because they could not spy
Th' eclipse which was invisible."

Surely these weren't the only two state astronomers to lose their heads, given how erratic solar eclipses can be in any specific geographic location. With so much at stake, precision was well sought after. By 720 BC, some Chou Dynasty astronomers recognized eclipses as "naturally" occurring phenomena, and not heavenly commentary on who held any particular throne. Still, diligent record-keeping continued up through the ages.

Oracle Bone
By the turn of the millennium, the Chinese had a firm grasp of what actually caused eclipses, and by 206 AD, they were predicting cycles by analyzing lunar orbits. Their records show that between 600 and 1300 AD, their solar eclipse timing predictions were often accurate to within about 20 minutes!

To see how it's done in the modern day, see the NASA Eclipse Website.

Also be sure to join me on Twitter tomorrow for my #TriviaThursday series, with everything you need to know about #Eclipse dynamics and safe viewing this weekend!

Monday, June 1, 2020

The Space Anniversary I'm Glad We Don't Celebrate

"Putting a man in space is a stunt. Man can do no more than an instrument, in fact, he can do less. There are far more serious things to do than indulge in stunts. As yet, the American people do not understand the distinctions and we in this country are prone to rush at any new thing. I do not discard completely the value of demonstrating to the world our skills, nor do I under-value the effects on morale of the spectacular. But the present hullabaloo on the propaganda aspects of the space program leaves me entirely cool." 

  Vannevar Bush Chairman of the Board Governors of the Massachusetts Institute of Technology < Well, what a relief it wasn't up to you, Vann man! The above excerpt is from a statement to the Congressional Committee on Science & Astronautics, made in June of 1960. And it's a 60th anniversary I'm pretty happy we don't celebrate. 

Vannevar Bush

Is it just me, or does he look like Gandalf?

 Of course, we're all very happy that Vannevar Bush (1890-1974) helped to end World War Two, made possible the position of "Science Advisor to the President" and founded the National Science Foundation... but after reading some of his materials (this is the sort of light reading with which I fill my free time), I'm equally happy that he was neither heeded nor funded by the federal government at this point in his career. This is one of those funny things, where I was reading biographical and technical information on a historical scientist, not intending to find any references to space or human exploration. 

While I knew Vannevar Bush had been on some aeronautics councils after WWII, I'd never known he worked long enough to speak to Congress about the space program. So shocked to find this excerpt... but I suppose the content was inevitable at the time. Not everyone was on board! 

Vannevar Bush Vannevar Bush represented the ideals and thought-paradigms of the previous generation -- one that wasn't ready to move forward, out of their protective stance made necessary by war. While he was happy to keep pace with and reward emerging scientific research, he represented a faction of our government who was not willing to seek new frontiers in the stars... and I cannot help but wonder if our current science advisers suffer from the same pessimistic blindness. 

 Do they also believe astronauts are merely stuntmen? No one walks around these days saying, "Wow, he sure hit the nail on the head 50 years ago. We should have spent all that money on something else and just been content with the practical applications of science instead of inspiring the world." 

And... in another 50 years?