Wednesday, December 19, 2018

What are the Stars?

The stars were conceptually intractable. What they were was never understood until modern times, but by 600 BCE when Odyssey was written down, constellations had names. “Glorious Odysseus, happy with the wind, spread sails and taking his seat artfully with the steering oar he held her on her course nor did sleep ever descend on his eyelids as he kept his eye on the Pleiades and late-setting Bo├Âtes and the Bear, to whom men give also the name of the Wagon, who turns about in a fixed place and looks at Orion and she [the Bear] alone is never plunged in the wash of the Ocean. For so Kalypso, bright among goddesses, had told him to make his way over the sea, keeping the Bear on his left hand.” The Odyssey, from the translation by Richmond Lattimore, Perennial Classics HarperCollins 1999. Cited at http://ircamera.as.arizona.edu/Astr2016/lectures/ancientast.htm
 
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Fraunhofer Bicentennial 1987
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Anaxagoras, Democritus, and other ancient philosophers suggested that the stars are Suns very far away. However, close as it sounds to the accepted facts, they lacked any scientific evidence for that claim. Perhaps the most cogent insight was from the Native Americans who called them the campfires of the council of chiefs. At least, that was based on experience. Apparently, some savants of medieval Europe suggested that the stars are holes in the sphere that separates us from  heaven. For that, no experiential evidence exists.

Giordano Bruno was burned at the stake in 1600 in part for claiming a multiplicity of worlds but in the next generation the fact that the Sun is another star and the stars are suns very far away was accepted, albeit without proof. Christiaan Huygens approximated the distance to Sirius by assuming that it is as bright as the Sun. His assumption was false, but his method underscores the fact that the nature of the stars was becoming accepted.

The problem was that the best telescopes that revealed stunning details of the Moon, Jupiter, and Saturn told us nothing new about stars. Anaxagoras said that the Milky Way is composed of very many stars, a fact that can be observed. That much the telescope could show in clear detail. But Sirius is just Sirius. 

It was not until 1814 that Joseph Fraunhofer invented the spectroscope. By 1817 he had completed many experiments with various sources, including sunlight. He died young, but forty years later, Gustav Kirchhoff and Robert Bunsen continued the project he began. They applied spectroscopy to the sun. Following them, William Huggins (1824-1910), Angelo Secchi (1818-1878) and Edward Charles Pickering (1846-1919) were among those who measured and catalogued the spectra of stars. We finally had empirical evidence that unified our particular star with all the other suns. 

 

PREVIOUSLY ON NECESSARY FACTS

Before Email

Patterns in Pi 

Bringing Philosophy to Athens: Aspasia of Miletus 

Awesome Austin Foods at the Wheatsville Co-op 

 

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