IH II Midterm Study Guide Questions
1. In his 1609 letter to the chief magistrate of Venice, Galileo proposes that the
telescope, a new invention, is
... [Show More] "a thing of inestimable benefit" for what type of
applications? (7/8). At this point, what was Galileo "obviously more concerned with"?
(9/10). - ANSWER-When writing his 1609 letter to the chief magistrate of Venice, Galilei
was more concerned with the benefits the telescope could yield to improve standards
on earth, namely navigation for sailors. As such, Galilei was less concerned with the
opportunities the telescope could lend to studying astronomy or other celestial beings.
1. At what point did Galileo begin his astronomical observations, and what was his first
subject? (9/10). - ANSWER-Galileo began his astronomical observations in mid- to late1609, and his first subject was the Moon.
1. Briefly, what characterized the "prevailing geocentric cosmology of Aristotle"?
(10/11). How was the Copernican theory different? (11/11-12). - ANSWER-The
prevailing geocentric cosmology of Aristotle was characterized by the belief that the
heavens were devoid of imperfections, and any perceived imperfections were not
reflective of the cosmos. Conversely, the Copernican theory was different by blurring
the distinction between earth as the realm of corruption and imperfection, and the
alleged perfect cosmos.
1. What did Galileo discover that was "completely unknown to the great philosophers of
Antiquity"? (16/17). - ANSWER-Galileo discovered that the planet Jupiter possessed
four moons in its orbit. This revealed there were at least two centers of motion of
universe, which challenged prevailing Aristotelian thought.
Galileo's first point, in his letter to Cosimo II de Medici, has to do with preserving "from
oblivion and ruin names deserving of immortality" (29/31). How is such preservation
usually accomplished? How does Galileo propose to preserve Cosimo's name? -
ANSWER-According to Galilei, traditional methods of preserving an individual are in
statues and written records. Alternatively, Galilei proposes naming the four discovered
moons of Jupiter after Cosimo Medici's family.
1. What analogy does Galileo draw between the moons of Jupiter and the moral
attributes of Cosimo? (31/33). What name, specifically, does Galileo propose for
Jupiter's newly discovered moons? (32/34). - ANSWER-The analogy Galilei draws
between the moons of Jupiter and the moral attributes of Cosimo is like the moons of
Jupiter being at most a short distance from Jupiter the planet, the moral attributes of
Cosimo constantly orbit him, influencing his decision making and never departing from
him. The name Galilei specifically proposes for Jupiter's newly discovered moons is that
of Medici's family: the "Medicean Stars."
1. Before revealing his findings, Galileo urges "all those who wish to make such
observations to be forewarned" (38/40). About what? What does Galileo mean by the
phrase "true philosophy"? (39/41). (Also, see Galileo's comments on philosophers and
"wordy arguments," p. 62/64.) - ANSWER-Before revealing his findings, Galilei urged
"all those who wish to make such observations to be forewarned" that the observations
he made pertaining to the Moon, Jupiter, and various constellations can only be made
using a spyglass, or telescope, that both magnifies by the hundreds and is not distorted
to the point obscurity. In describing "true philosophy" Galilei is alluding to empirical
observation.
1. In general, what does Galileo observe about the moon? What is his hypothesis about
its surface? To what other planet does Galileo compare the moon? - ANSWER-In
general, Galilei observes that the moon is covered by several dark and light spots of
various sizes on the light and dark sides of the moon, respectively. In addition, he also
observes the boundary line separating the light and dark sides of the moon is not a
perfect curvature, but a jagged, imperfect division. As such, Galilei's hypothesis about
the moon is that the lunar surface is not a uniform, smooth spherical body, and is
instead defined by countless valleys and mountain ranges. With this hypothesis, Galilei
directly compares the Moon to Earth.
1. Why, according to Galileo, do "very many bright points appear within the dark part of
the moon"? (42/44). Indeed, why are there dark spots in the light part of the moon? -
ANSWER-According to Galilei, bright spots appear within the dark part of the moon
because the Sun's light first illuminates the mountaintops before the valleys and
lowlands at the base of the mountains. Conversely, there are dark spots on the light part
of the moon because the Sun's light relative to the moon is at an angle that illuminates
mountain ranges directly facing the Sun while cloaking non-direct mountain ranges in
darkness.
1. On the face of the moon, Galileo observes "a certain cavity larger than all others and
of a perfectly round figure" (47/49). How does he explain this "cavity"? To what does he
compare it? - ANSWER-Galilei explains the larger and seemingly round "cavity" as
further evidence of the Moon's imperfect topography, as it is partially illuminated and
partially shadowed depending on the Moon's relative position to the sun. He compares
this cavity to the region of Bohemia, a predominately flat region of Europe surrounded
by lofty mountain ranges.
1. What "great doubt" does Galileo address? (48/50). How does he respond to the
skepticism of those who may hold it? - ANSWER-The "great doubt" that Galilei
addresses is an anticipated criticism of his hypothesis pertaining to the peripheries of
the moon. Specifically, if the lunar surface's topography is irregular, why are said
imperfections confined only to the observable face, and not around the peripheries?
Galilei addresses this anticipated skepticism by arguing the various rows of mountain
ranges and prominences on the lunar surface overlap each other to the point that gaps
between imperfections cannot be observed.
1. Galileo notes that sometimes when we look at the crescent moon "we will see not
only the extreme edge of the dark part shining with a faint brightness, but the entire
surface of the Moon — that part, namely, that does not yet feel the brightness of the
Sun — made white by some not inconsiderable light" (53/55). What is the source of this
"faint brightness"? What answers have "those applying themselves to philosophy"
offered to the previous question? (54/56). - ANSWER-The source of the faint
brightness, or "secondary brightness" as described on page 55, is the sun. In
comparison, those who subscribe to or expound philosophy attributed secondary
brightness as natural, self-emanating brightness of the moon, bestowed by Venus, or
bestowed by the Sun penetrating the lunar mass with its rays.
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