Sunspot Cycles
Dark regions on the Sun, called sunspots, were studied in 1610 by Galileo, who turned the newly invented telescope on objects in the sky. A lively debate over the origin and significance of sunspots ensued. We now know that the sunspots are relatively cool regions on the Sun, over 1,000 degrees cooler than the surrounding solar surface -still hot, by terrestrial standards, of course. As a consequence, the sunspot gas is less bright than the surrounding gas, appearing dark in comparison. The number of spots on the Sun increases and decreases from year to year, with an average of about 11 years from one maximum to the next; this regular variation is called the sunspot cycle.
Scientists are unable at present to predict how strong a cycle will be in terms of sunspot number. For example, a set of papers in the late 1990s tried to predict how high the peak of the cycle would be in the year 2000. Of the set, one paper predicted that it would be higher than average, another predicted that it would be lower than average, and a third predicted that it would be average. It has also been suggested that there are other cycles that last longer than 11 years, and these cycles are superimposed on the 11-year cycle. The evidence for these longer cycles is still marginal, and unless we can find a way to extend the historical sunspot record back before 1610.we will just have to wait longer to obtain higher statistical certainty for such cycles.
In the meantime, the 11-year sunspot cycle is very obvious. What drives the sunspot cycle is a cycle in the intensity of the Sun’s magnetic field strength. These magnetic fields, generated inside the Sun, create a large assortment of dynamic effects that are collectively called the solar activity cycle. The sunspot cycle is the most easily observed manifestation of the activity cycle.
About a hundred years ago, an English astronomer named E. Walter Maunder noticed something puzzling about the historical sunspot record: there seemed to have been very few spots on the Sun in the decades after Galileo’s discovery. Sunspots were generally absent for about 70 years. Maunder’s work was forgotten for decades and then rediscovered by astronomers in the 1970s. This “Maunder minimum” may indicate that the sunspot cycle turned off for a time in the 1600s, which would imply that the sunspot cycle is superficial rather than fundamental to the Sun. Long-period cycles like this may turn out to be important for understanding the linkage between the Sun and the weather on Earth. In particular, the Maunder minimum corresponded to a relatively cool time in Europe sometimes known as the Little lce Age.
Were there really fewer sunspots during 1645-1715, as Maunder suggests? Or were people just not watching closely enough? The fact that scientific papers on the subject of sunspots appeared during this time indicates that they did indeed attract attention and would have been written about if they had been observed. Contemporary reports state that observers had been searching in vain for years to see even a single spot on the Sun. Further, other indicators of the Sun’s magnetic field also were weak or absent during much of that time. For example, records show that the Sun’s corona (the hot, outer atmosphere of the Sun. visible during solar eclipses) was not strong when seen at eclipses during that interval
In the 1980s. astronomers established that several other stars also have solar activity cycles. These observers followed a certain feature of the color spectrum of light that is typical of solar activity yet is visible from the around. and noticed that the strength of this feature varied in nearby solar-type stars with cycles ranging from a few years to 15 years or so. Some stars may have longer cycles, but more years of observation are needed to be sure of that. They also found some solar-type stars that appeared to be in a “Maunder minimum” phase of very low activity. Enough observations of this type could establish how much of the time the Sun is in an extended minimum of activity, by determining what fraction of the solar-like stars are in such a state at any given time
1
Dark regions on the Sun, called sunspots, were studied in 1610 by Galileo, who turned the newly invented telescope on objects in the sky. A lively debate over the origin and significance of sunspots ensued. We now know that the sunspots are relatively cool regions on the Sun, over 1,000 degrees cooler than the surrounding solar surface -still hot, by terrestrial standards, of course. As a consequence, the sunspot gas is less bright than the surrounding gas, appearing dark in comparison. The number of spots on the Sun increases and decreases from year to year, with an average of about 11 years from one maximum to the next; this regular variation is called the sunspot cycle.
The word “ensued” in the passage is closest in meaning to
Vocabulary Questions词汇题
AContinued
Bwas necessary
Cwas resolved
Dfollowed
2
Scientists are unable at present to predict how strong a cycle will be in terms of sunspot number. For example, a set of papers in the late 1990s tried to predict how high the peak of the cycle would be in the year 2000. Of the set, one paper predicted that it would be higher than average, another predicted that it would be lower than average, and a third predicted that it would be average. It has also been suggested that there are other cycles that last longer than 11 years, and these cycles are superimposed on the 11-year cycle. The evidence for these longer cycles is still marginal, and unless we can find a way to extend the historical sunspot record back before 1610.we will just have to wait longer to obtain higher statistical certainty for such cycles.
In paragraph 2, why does the author discuss the differing conclusions of a set of papers written in the late 1990s?
Factual Information Questions事实信息题
ATo support the claim that scientists are not good at predicting how many sunspots will appear in a given cycle.
BTo show that scientists are not yet able to agree on what constitutes an “average” number of sunspots.
CTo demonstrate how little evidence scientists have to predict when the peak of a sunspot cycle will occur
DTo provide evidence of sunspot cycles that lasted much longer than 11 years.
3
About a hundred years ago, an English astronomer named E. Walter Maunder noticed something puzzling about the historical sunspot record: there seemed to have been very few spots on the Sun in the decades after Galileo’s discovery. Sunspots were generally absent for about 70 years. Maunder’s work was forgotten for decades and then rediscovered by astronomers in the 1970s. This “Maunder minimum” may indicate that the sunspot cycle turned off for a time in the 1600s, which would imply that the sunspot cycle is superficial rather than fundamental to the Sun. Long-period cycles like this may turn out to be important for understanding the linkage between the Sun and the weather on Earth. In particular, the Maunder minimum corresponded to a relatively cool time in Europe sometimes known as the Little lce Age.
According to paragraph 4, when did the “Maunder minimum” occur on the Sun?
Rhetorical Purpose Questions修辞目的题
AFor several decades beginning in the 1970s
BAbout a hundred years ago
CIn the 1600s
D70 years before Galileo’s discovery
4
About a hundred years ago, an English astronomer named E. Walter Maunder noticed something puzzling about the historical sunspot record: there seemed to have been very few spots on the Sun in the decades after Galileo’s discovery. Sunspots were generally absent for about 70 years. Maunder’s work was forgotten for decades and then rediscovered by astronomers in the 1970s. This “Maunder minimum” may indicate that the sunspot cycle turned off for a time in the 1600s, which would imply that the sunspot cycle is superficial rather than fundamental to the Sun. Long-period cycles like this may turn out to be important for understanding the linkage between the Sun and the weather on Earth. In particular, the Maunder minimum corresponded to a relatively cool time in Europe sometimes known as the Little lce Age.
According to paragraph 4, what is one reason why the “Maunder minimum” is significant?
Factual Information Questions事实信息题
AIt demonstrates that the sunspot cycle is a fundamental characteristic of the Sun.
BIt suggests a possible connection between solar activity and temperatures on Earth.
CIt helps explain why the effects of sunspots on Earth were not understood until the 1970s
DIt helped scientists identify with more precision when the Little Ice Age began in Europe.
5
Were there really fewer sunspots during 1645-1715, as Maunder suggests? Or were people just not watching closely enough? The fact that scientific papers on the subject of sunspots appeared during this time indicates that they did indeed attract attention and would have been written about if they had been observed. Contemporary reports state that observers had been searching in vain for years to see even a single spot on the Sun. Further, other indicators of the Sun’s magnetic field also were weak or absent during much of that time. For example, records show that the Sun’s corona (the hot, outer atmosphere of the Sun. visible during solar eclipses) was not strong when seen at eclipses during that interval
Which of the following can be inferred from paragraph 5 about the Sun’s corona?
Factual Information Questions事实信息题
AIts strength is related to that of the Sun’s magnetic field
BIt is strongest when there are fewer sunspots.
CScientists have only recently begun observing it during solar eclipses.
DIt appears less bright when there is a solar eclipse.
6
Were there really fewer sunspots during 1645-1715, as Maunder suggests? Or were people just not watching closely enough? The fact that scientific papers on the subject of sunspots appeared during this time indicates that they did indeed attract attention and would have been written about if they had been observed. Contemporary reports state that observers had been searching in vain for years to see even a single spot on the Sun. Further, other indicators of the Sun’s magnetic field also were weak or absent during much of that time. For example, records show that the Sun’s corona (the hot, outer atmosphere of the Sun. visible during solar eclipses) was not strong when seen at eclipses during that interval
Why does the author pose the questions at the beginning of paragraph 5?
Rhetorical Purpose Questions修辞目的题
ATo suggest that evidence challenging Maunder’s observations has not been discovered yet
BTo argue that Maunder’s data should not have been disregarded for so long
CTo introduce reasons why scientific papers of the 1600s agreed with Maunder
DTo introduce information that suggests that Maunder was correct
7
In the 1980s. astronomers established that several other stars also have solar activity cycles. These observers followed a certain feature of the color spectrum of light that is typical of solar activity yet is visible from the around. and noticed that the strength of this feature varied in nearby solar-type stars with cycles ranging from a few years to 15 years or so. Some stars may have longer cycles, but more years of observation are needed to be sure of that. They also found some solar-type stars that appeared to be in a “Maunder minimum” phase of very low activity. Enough observations of this type could establish how much of the time the Sun is in an extended minimum of activity, by determining what fraction of the solar-like stars are in such a state at any given time
Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
Sentence Simplification Questions句子简化题
AThese observers noted that in most stars like the Sun, features of the color spectrum are difficult to follow because they are not visible from the ground for up to 15 years at a time
BOver a period of 15 years, these observers followed a certain feature of the color spectrum in sun-like stars that is visible from the ground and typical of solar activity.
CObservers noted that in nearby solar-type stars, the strength of a color spectrum feature that is typical of solar activity has cycles that are from a few years to about 15 years long
DObservers followed a certain feature of the color spectrum in a nearby star and the Sun for up to 15 years and observed similar changes in both stars
8
In the 1980s. astronomers established that several other stars also have solar activity cycles. These observers followed a certain feature of the color spectrum of light that is typical of solar activity yet is visible from the around. and noticed that the strength of this feature varied in nearby solar-type stars with cycles ranging from a few years to 15 years or so. Some stars may have longer cycles, but more years of observation are needed to be sure of that. They also found some solar-type stars that appeared to be in a “Maunder minimum” phase of very low activity. Enough observations of this type could establish how much of the time the Sun is in an extended minimum of activity, by determining what fraction of the solar-like stars are in such a state at any given time
According to paragraph 6, which of the following could help determine how often the Sun is in a state of minimum activity?
Factual Information Questions事实信息题
ADetermining the average length of solar activity cycles for stars that are similar to the Sun
BDiscovering how the activity cycles of nearby stars affect the Sun
CDetermining the percentage of other Sun-like stars that are in a state of minimum activity at any given time
DUnderstanding why the Sun experiences a “Maunder minimum” while other stars do not
9
Scientists are unable at present to predict how strong a cycle will be in terms of sunspot number. For example, a set of papers in the late 1990s tried to predict how high the peak of the cycle would be in the year 2000. Of the set, one paper predicted that it would be higher than average, another predicted that it would be lower than average, and a third predicted that it would be average. It has also been suggested that there are other cycles that last longer than 11 years, and these cycles are superimposed on the 11-year cycle. [■] The evidence for these longer cycles is still marginal, and unless we can find a way to extend the historical sunspot record back before 1610.we will just have to wait longer to obtain higher statistical certainty for such cycles.[■]
In the meantime, the 11-year sunspot cycle is very obvious. [■] What drives the sunspot cycle is a cycle in the intensity of the Sun’s magnetic field strength. [■] These magnetic fields, generated inside the Sun, create a large assortment of dynamic effects that are collectively called the solar activity cycle. The sunspot cycle is the most easily observed manifestation of the activity cycle.
Look at the four squares [■] that indicate where the following sentence could be added to the passage
It is also clear that the sunspot cycle is only a sign of a more general solar activity cycle.Insert Text Questions句子插入题
Where would the sentence best fit？Click on a square sentence to the passage.
10
Sunspots are areas of the Sun’s surface that are darker than surrounding areas.
Prose Summary Questions概要小结题
Select 3 answers
AFirst noticed in the 1600s, sunspots occur due to extreme changes in temperatures on the surface of the Sun, which often rise and fall by thousands of degrees Kelvin.
BSeveral centuries ago, there was a period during which very few sunspots occurred, and it seems that the Sun’s magnetic field was very’ weak or absent at that time
COther, similar stars also have solar activity cycles, and studying them may help answer important questions about the Sun’s cycles.
DThe cycle in the intensity of the Sun’s magnetic field produces different effects, and the 11-vear cycle in the number of sunspots is one of these effects.
EThough evidence is limited, both Galileo’s and Maunder’s observations suggest that temperatures on Earth may be cooler when sunspots are more frequent.
FSince several more years of observation will be needed to understand sunspots, astronomers are shifting their focus toward more easily measurable signs of solar activity.
