Ch. 52. Unraveled Starlight, William Huggins. “The first person to analyze starlight using a spectroscope recounts the moment when he solved the riddle of the nebulae.”

Comte passages:

•          What were some of the “theological and metaphysical influence(s)” on astronomical science to which Comte refers?

•          How might Comte react to the idea, that we might someday send people to the moon, or to Mars?

•          What does Comte think we may know about stars? Why does he differentiate between scientific investigation of stars, and of the sun and planets? Can you think of a similar division in present day science?

First Huggins passage:

•          Helium is present in the earth’s atmosphere, but it was first discovered as existing in the sun. Why didn’t we know about it before that?

•          Spectroscopy relies on the assumption that elements and compounds emit and absorb light in the same way, on the earth and in the heavens. How is this assumption justified?

Second Huggins passage:

•          What was similar about Huggins’ and Galileo’s experiences?

•          Why was Huggins so excited about the new method of observation?

Third Huggins passage:

•          Why did Huggins use solar light reflected from the moon as a test of his apparatus?

•          Great discoveries followed “almost every night,” as the astronomical observatory “began for the first time to take on the appearance of a laboratory.” Why is this significant?

Fourth Huggins passage:

•          What does it matter, whether some nebulae are made of gas, or all are collections of stars?

•          The existence of gaseous nebula allows Huggins to speculate on how the solar system may have been formed. Where is the distinction now (i.e. in Huggins mind), between earthly phenomena and the heavens?

Fifth Huggins passage:

•          How does one see motion of the stars across the line of sight?

•          Why is it much more difficult to see motion in the line of sight? How did Huggins solve this problem?

•          Why would anybody want to know, how the stars move in detail? Aren’t they supposed to be “fixed” stars?

•          What two scientific principles or methods were combined to measure the motion of stars in the line of sight? Why was it necessary “to construct a spectroscope of greater power for this research?”

•          Why is it that well known, experienced astronomers were slow to take up the new techniques developed by Huggins?

The article as a whole:

•          In what sense did Huggins unravel starlight?

•          Does it seem reasonable or likely, that by making measurements in a laboratory on earth, we can really learn about the chemical composition of a distant star? About the star’s motion? Is vision in some fundamental way different from other senses? Are there some things that one could never learn from a distance?

•          When Galileo made his discoveries about the cosmos, he got into big trouble. Nothing like that happened to Huggins, or to any of his colleagues. How had society changed from the seventeenth to the nineteenth centuries? How had science changed?

•          Describe the limits of astronomical or cosmological scientific research in Huggins’ time, and contrast these to the limits in Galileo’s time, and in Ptolemy’s time. What are the limits today? Are there some ultimate limits to this type of research that will not or should not ever be exceeded?