Astronomy
(Geocentric & Heliocentric theory) --
TPO 21
Professor: (1) Ok, we have been talking about how
throughout history, it was often difficult for people to give up ideas which have
long been taken for granted as scientific truth, even if those ideas were
false. In Astronomy, for example, the distinction between the solar system and
the universe wasn’t clear until modern times. The ancient Greeks believed that what we called the solar
system was in fact the entire universe, and that the universe was geocentric.
Geocentric means Earth-centered, so the geocentric view holds that the Sun, the
planets, and the stars, all revolve around the Earth, which is stationary. Of
course, we now know that the planets, including Earth, revolve around the Sun,
and that the solar system is only a tiny part of the universe. (2) So,
why did the ancient Greeks believe that the Earth was the center of the
universe? Well, it made sense to them. Observations of the sky make it appear
as if the Sun, the moon, and the stars all revolve around the Earth every day,
while the Earth itself stayed in one place. And this view is also supported by
their philosophical and religious beliefs about the origin and structure of the
universe. It was
presented in the works of well-known Greek philosophers as early as the fourth
century B.C.E., and the geocentric theory continue to prevail in Western
thought for almost 2,000 years, until the 17th century.
(3) Now,
what’s especially interesting is that when astronomical observations were made
that seemed
to be inconsistent with the geocentric view, the ancient Greeks did not really
consider alternative theories. It was so intuitive, so sensible that the Earth
was the center of the universe that astronomers found ways to explain those
seemingly inconsistent phenomena within the geocentric view.
For example, Greek astronomers made excellent, very accurate observations of
the movements of the planets, but the observations revealed a bit of a problem.
The geocentric theory said, that the planets would move around the Earth in one
direction. (4) However,
astronomers noticed that at times, several planets seem to stop moving in one
direction and start moving backward in their orbits around the Earth, and they
came up with a theory that these planets themselves moved in smaller circles
called epicycles as they travelled around the Earth.
Here’s a picture of what they imagined. You see how this epicycle theory
could account for the seemingly backward motion of the planet. Of course, today
we know that this appearance of backward motion is caused by the fact that
Earth, as well as other planets, all move in their own orbits around the Sun,
and the relative movements of the planets with respect to each other can get
quite complex. However, there were a few astronomers in Greece and other places
who didn’t agree with the geocentric view, for example, a Greek astronomer who
lived in the third century B.C.E. He proposed the theory that our planetary
system might be heliocentric; his name was Aristarchus. Heliocentric means
Sun-centered, that the Earth revolves around the Sun.
(5) Aristarchus
recognized from his calculations that the Sun was much larger than the Earth
and other planets. It was probably this discovery that led him to conclude that
the universe is heliocentric. I mean, isn’t it more sensible to
think that a smaller heavenly body would orbit a larger one, rather than the
opposite? However, his proposition was rejected largely based on other
scientific beliefs held at the time, which all made sense in a way even if they
were incorrect. (6)
Let me mention two objections Greeks made to Aristarchus’s theory. First,
they believe that everything that moves creates its own wind, so to speak,
everyone has this experience when you are running, right? So, they thought that
if the Earth itself was moving, there would have to be a constant wind blowing,
sweeping them off their feet, and of course there wasn’t. And second, the idea
of an Earth that moved didn’t fit in with the ancient Greeks’ understanding of
gravity. They thought that gravity was basically a natural tendency of all
things to move towards the center of the universe, which was the Earth, or the
center of the Earth, so that explains why apples and other falling objects were
falling straight down. If the Sun was at the center of the
universe, things would fall toward the Sun and away from the Earth, which of
course they didn’t. So these were some of the reasons they rejected the
heliocentric theory.
1. What is the purpose of the lecture?
A. To explain how the
heliocentric theory of the universe developed
B. To give an example of the
persistence of traditional theories
C. To show that scientific
knowledge is rarely influenced by philosophy
D. To compare methods in observational and
theoretical astronomy
答案：B
解析：
Professor: Ok, we have been talking about how throughout history, it was often difficult for people to
give up ideas which have long been taken for granted as scientific truth, even
if those ideas were false. In astronomy, for example, the distinction between
the solar system and the universe wasn’t clear until modern times.
由以上講述得知，教授的講課目的在於提出例子，用以佐證傳統理論往往在歷史中延續許久。
關鍵訊號詞：we have been talking about ...... / In
astronomy, for example ......
2. Why did the ancient Greeks hold the geocentric
view of the universe?
Click on 2
answers.
A. The Sun appeared to them to revolve around Earth.
B. They had not developed methods of gathering accurate
data on the movement of planets.
C. Their religious and philosophical beliefs supported
this view.
D. Some of the
planets in the solar system had not been discovered yet.
答案：AC
解析：
Professor: ...... So, why did the ancient Greeks believe that the
Earth was the center of the universe? Well, it made sense to them. Observations
of the sky make it appear as if the Sun, the moon, and the stars all revolve around
the Earth every day, while the Earth itself stayed in one place. And this view
is also supported by their philosophical and religious beliefs about the origin
and structure of the universe.
教授明確指出兩個原因：1. 在古人的觀察中，太陽是圍著地球轉的 2. 古人所持的觀點也得到哲學與宗教思想的支持。
關鍵訊號詞：So, why did ...... / And this view is also
supported by ......
3. Why does the
professor point out that Greek astronomers tried to explain new astronomical
discoveries within the geocentric concept?
A. To explain why early astronomers found new discoveries
exciting
B. To explain why some claims made by ancient Greek
astronomers conflicted with claims made by earlier astronomers
C. To illustrate that the geocentric concept was open to
many interpretations
D. To illustrate
that the geocentric concept itself was not considered questionable
答案：D
解析：
Professor: ...... (3) Now, what’s especially interesting is
that when astronomical observations were made that seemed to be inconsistent
with the geocentric view, the ancient Greeks did not really consider
alternative theories. It was so intuitive, so sensible that the Earth was the
center of the universe that astronomers found ways to explain those seemingly
inconsistent phenomena within the geocentric view.
由以上可知，原因是新理論出現時，古人心中先入為主的觀念使其不考慮修改相關理論。
關鍵訊號詞：what’s especially interesting is that ......
4. Why does the
professor discuss the epicycle theory?
A. To explain why early astronomers started measuring the
velocity of the planets
B. To explain why the astronomer Aristarchus rejected the
geocentric model
C. To show how early astronomers explained the apparent
backward motion of some planets
D. To show that
early astronomers believed that all planets moved in their own orbits around
the Sun
答案：C
解析：
Professor: ...... However,
astronomers noticed that at times, several planets seem to stop moving in one
direction and start moving backward in their orbits around the Earth, and they
came up with a theory that these planets themselves moved in smaller circles
called epicycles as they travelled around the Earth.
教授說明epicycles theory的出現是由於早期天文學家為了解釋several planets
start moving
backward。
關鍵訊號詞： However, astronomers noticed that ......
5. In the professor's view, what might have caused
Aristarchus to propose the heliocentric theory?
A. The discovery that Earth was much smaller than the Sun
B. The lack of proof supporting the theory of epicycles
C. The influence of well-known philosophers
D. The apparent
stability of Earth
答案：A
解析：
Professor: ...... Aristarchus
recognized from his calculations that the Sun was much larger than the Earth and
other planets. It was probably this discovery that led him to conclude that the
universe is heliocentric.
教授指出，可能是因為Aristarchus發現太陽要比地球大很多，因此促使他提出理論。
關鍵訊號詞： It was probably ......
that ......
6. What were two
arguments ancient Greeks used to reject the heliocentric model? Click on 2
answers.
A. More stars would be visible in a heliocentric
universe.
B. A moving Earth would create a strong wind.
C. Aristarchus's calculations were inaccurate.
D. Objects fall
toward the center of the universe
答案：BD
解析：
Professor: ...... Let me mention two
objections Greeks made to Aristarchus’s theory. First, they believe that
everything that moves creates its own wind, so to speak, everyone has this
experience when you are running, right? So, they thought that if the Earth
itself was moving, there would have to be a constant wind blowing, sweeping
them off their feet, and of course there wasn’t. And second, the idea of an
Earth that moved didn’t fit in with the ancient Greeks’ understanding of
gravity. They thought that gravity was basically a natural tendency of all
things to move towards the center of the universe, which was the Earth, or the
center of the Earth, so that explains why apples and other falling objects were
falling straight down.
教授指出反對的原因有兩個：1. 他們認為物體運動會產生風 2. 他們認為物體下落應該會朝向宇宙中心，也就是地球。
關鍵訊號詞：First, ...... / And second, ......
本文出自TPO21
戴爾美語榮獲台灣區托福、GRE、雅思三考場，原地上課考試
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