Narrator: Listen to part of a lecture in an astronomy class.
Professor: I want to relate a story about how astronomers began to solve a longstanding puzzle. For more than 1,000 years, astronomers observed a phenomenon, without knowing what it was. And even though today we can start to answer it, there are still lingering questions. But what we know about this phenomenon started with the creation of the telescope. So imagine you were an early astronomer, and you have just created one of the first telescopes. Tell me, what would you be interested in observing? Anyone?
Female Student: The Moon…
Professor: Right…
Male Student: And, maybe, the motion of the planets?
Professor: Yes…
Female Student: Stars.
Professor: Okay. What else? What about something you see every day? How about the Sun? I’m sure you’ve heard of something called sunspots. Well, so had astronomers at the time. They just didn’t know what they were.
You can see sunspots by looking carefully towards the Sun. They are areas that are darker than the rest of the Sun. They can look black, but really they’re just dark relative to the bright Sun surrounding them. Because the largest ones are visible without a telescope, they have been documented since the year 807 CE, and probably seen even before that. Sunspots can appear for hours, or even days. Some years a lot of sunspots are observed, and other years it’s hard to find even one.
What could these mysterious dark spots be? At the time, the school of thought founded by Aristotle claimed that the heavens—what we now think of as outer space—were unchanging. So, this school of thought believed the Sun couldn’t be changing. Instead, these dark spots were simply satellites of the Sun, and we observed them when their revolution brought them between the Sun and the Earth. But others believed that these were actually spots on the Sun that appeared and disappeared.
Which of these two theories, at least initially, was more believable?
Male Student: The satellite theory.
Professor: And why?
Male Student: Well, most people probably believed the Sun couldn’t change. And the satellite theory supported that, right?
Professor: Right. But there was still some debate. Christoph Scheiner was one of the first to hypothesize that sunspots were satellites—and he wrote to Galileo Galilei asking for his input. Galileo thought that these sunspots appeared on the Sun. There were several letters back and forth in which these two astronomers debated their theories. These letters were published in newspapers, so the public could evaluate both sides. Both men were using telescopes to observe sunspots, and for the most part, they agreed on what they were observing. But they disagreed on what it meant.
But what could be done to resolve the debate? How can you measure something so far away? Any thoughts? Jamie?
Female Student: Well, what about watching the movement of the sunspots? Because, if a sunspot is orbiting the Sun, we should be able to watch its revolution.
Professor: Yes, but there’s an issue. The Sun itself is rotating, and the sunspots themselves would therefore move across the surface of the Sun. So if you see a sunspot that migrates from one end of the Sun the other, it can mean a few things.
Female Student: Oh… it could be a satellite or not.
Professor: And it’s hard to tell which. But Galileo had an idea. Instead of just making observations, he tracked the sunspots at particular times of the day to see whether a regular revolution was occurring. Without going too much into the details, he found pretty good evidence that the sunspots were not orbiting, but were appearing and disappearing.
So what do you think Scheiner’s reaction was?
Male Student: Well, he could have changed his mind, or maybe he was just stubborn.
Professor: Right. Fortunately, Galileo’s and Scheiner’s letters were very polite and collegial, so when Galileo presented what was nearly irrefutable evidence that the sunspots were on the Sun, Scheiner changed his mind. He began publishing articles which suggested that, in fact, the heavens could change. That they weren’t perfect.
So there are two lessons to take from this. One is that collaboration is essential. In science, you have to keep testing and challenging your theories, and one of the best ways to do that is to work with somebody who has a different opinion. Two is that you want to keep an open mind. Sometimes the assumptions we hold are false.
Now, another reason why I brought this up today is that there is still debate surrounding sunspots. During years when there are fewer sunspots… it tends to produce a cooling effect on the Earth. Years with more sunspots cause higher temperatures. And there is evidence that the Sun is about to enter a period of fewer sunspots.
How does that impact our debate? Well, think about global climate change. There’s intense debate about what causes it. And if the Sun itself is going to change in a way that affects the global temperature, it will be much harder to argue with certainty what is causing the climate to change, and to what degree.
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What is the lecture primarily about? |
Gist-content. The professor is discussing a debate about sunspots and the eventual consensus that was reached about what they are. |
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| ✓ | A How astronomers debated and found the correct interpretation for an observed phenomenon |
Correct. The lecture focuses on the debate about sunspots. It was eventually determined that they are darker spots on the surface of the Sun, not orbiting satellites blocking parts of the Sun. |
| ✗ | B The discovery of various underlying causes of an astronomical phenomenon |
There was no discovery of “various” causes of the astronomical phenomenon. The debate was about what might cause the appearance of dark areas on or in front of the Sun. But there was only one cause that was finally determined: actual sunspots on the Sun itself. As for the underlying cause or causes of those spots on the Sun itself, the lecture never discusses the issue. |
| ✗ | C What astrologers first saw when they began to use telescopes |
There’s no mention of what astronomers first saw using telescopes. |
| ✗ | D An unresolved question about a phenomenon originally observed less than 1,000 years ago |
The question about what sunspots represent has been resolved. Also, the professor indicates that sunspots were first observed more than 1,000 years ago. |
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According to the lecture, how did sunspots appear to early astronomers? |
Detail. The professor indicates that sunspots were first observed as dark areas on the Sun’s surface. |
|
| ✗ | A Like orbiting bodies |
This was a theory to explain what early astronomers saw, not a description of what they saw. |
| ✓ | B Like dark areas |
Correct. The professor describes sunspots as dark areas on the Sun’s surface. |
| ✗ | C Like short flares of light |
This idea is not mentioned in the lecture. |
| ✗ | D Like brighter regions |
This idea is not mentioned in the lecture. |
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What does the professor imply was a consideration that may have led to Scheiner’s initial interpretation of sunspots? |
Inference. Scheiner theorized that sunspots were caused by bodies orbiting the Sun. The professor implies that this theory was fed by the Aristotelian belief that the heavens were unchanging. |
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| ✗ | A An observation of numerous satellites orbiting the Sun |
These satellites were theorized, but never observed. |
| ✗ | B A centuries-old understanding of sunspots |
The earliest theory mentioned regarding the source of sunspots is Scheiner’s theory. |
| ✓ | C A belief that the heavens could not change |
Correct. Scheiner originally theorized that sunspots were caused by bodies orbiting the Sun. This rejected the idea that sunspots existed on the surface of the Sun. The professor implies that Scheiner’s theory was fed by the Aristotelian belief that the heavens were unchanging. |
| ✗ | D An analogy drawn from observations of other stars |
Observations of other stars are not discussed in the lecture. |
Narrator: Listen again to part of the lecture. Then answer the question.
Professor: So, this school of thought believed the Sun couldn’t be changing. Instead, these dark spots were simply satellites of the Sun, and we observed them when their revolution brought them between the Sun and the Earth. But others believed that these were actually spots on the Sun that appeared and disappeared.
Which of these two theories, at least initially, was more believable?
Male Student: The satellite theory.
Professor: And why?
Narrator: Why does the professor say this:
Professor: And why?
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Function of What Is Said. In this quote, the professor describes the two theories about sunspots, and asks the class which of the theories was more believable at the time. |
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| ✗ | A To correct a different student’s error |
There are no other students involved in this discussion. |
| ✓ | B To encourage the student to elaborate on his answer |
Correct. The student is correct, the professor is simply looking for more detail. |
| ✗ | C To help the student recognize an error he has made |
On the contrary, the student is correct. The professor simply wants the student to elaborate on why he answered as he did. |
| ✗ | D To help the professor understand what this student meant. |
The student’s meaning was clear to the professor. |
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According to the professor, what was a result of the debate between Galileo and Scheiner? |
Detail. Scheiner’s theory was proven incorrect. He therefore rejected his own theory and accepted Galileo’s findings. |
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| ✓ | A In the end, Scheiner rejected his original theory. |
Correct. Galileo was able to prove his own theory, and through his letters, convinced Scheiner to change his mind. |
| ✗ | B The public began believing that the heavens were unchanging. |
This was the original assumption behind Scheiner’s theory. It was eventually refuted by Galileo’s findings. |
| ✗ | C Later astronomers showed more interest in studying the surface of stars. |
The professor does not mention this idea in the lecture. |
| ✗ | D Galileo became known as the foremost astronomer of his time. |
The professor does not mention this idea in the lecture. |
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During a year in which the Sun has a large number of sunspots, what impact is felt on Earth? |
Detail. The professor states that years with fewer sunspots have a cooling effect on the Earth, and that years “with more sunspots cause higher temperatures.” |
|
| ✗ | A Sunspots will exhibit faster movement than usual. |
The professor does not mention this idea in the lecture. |
| ✗ | B There will be less variation in global climate change. |
The professor does not claim that an increase in the number of sunspots will reduce variation in global climate change. Instead, he argues that the variability caused by changes in sunspot activity makes determining the causes of climate change harder to separate and measure. |
| ✗ | C There will be more satellites between the Earth and the Sun. |
This choice aligns with Schreiner’s original theory, which was proven false. |
| ✓ | D Temperatures on Earth will be higher than normal. |
Correct. As the professor notes, “more sunspots cause higher temperatures.” |