In 1979, John A. Eddy of the High Altitude Observatory and Aram A. Bo

Question

In 1979, John A. Eddy of the High Altitude Observatory and Aram A. Boornazian, a mathematician in Boston, concluded that the sun is contracting at a considerable rate, based on daily measurements of the sun’s image. They estimated the reduction of the sun’s horizontal diameter to be about two seconds of arc, or about 0.1 percent, per century. These findings sparked renewed debate over solar measurement and the possibility that our sun may be shrinking.

Heliologists contend that the brilliance of the sun’s disk, and the imperfect and variable transparency of the earth’s atmosphere, make observations from the earth’s surface unreliable. A better source of data regarding solar shrinkage is the duration of total solar eclipses, while a second statistically independent check is provided by the time the planet Mercury is visible against the solar disk. These observations allow a monitoring of changes in the sun’s diameter at reasonably regular intervals back to about the start of the 18th century, or roughly twice the number of years covered by the data used by Eddy and Boornazian.

When the observations of total solar eclipses over the past three centuries are analyzed in conjunction with the evidence of the transits of Mercury, the data indicate only a negligible change in the sun’s diameter. The percentage of decrease per century has been calculated to be only 0.007, with a 0.0008 percent margin of error.   1 
 1. The author argues that Eddy and Boornazian have

a. misrepresented experimental results in order to gain support for their conclusions
b. incorrectly surmised that the sun's diameter is independent of Mercury's orbit
c. probably drawn an incorrect conclusion due to their reliance on unreliable data
d. made several noteworthy breakthroughs in the field of solar measurement
e. wilfully ignored the existence of data pertaining to the duration of solar eclipses

2 
 2. According to the author, evidence that the sun is shrinking only at a negligible rate is based on

I. measurement of the length of solar eclipses
 II. measurement of the time during which Mercury can be observed crossing the sun's path
 III. daily measurements of the sun's image
 
a. I only 
b. II only 
c. III only 
d. I and II only 
e. I, II and III

3 
 3. It can be inferred from the passage that all of the following cast doubt on Eddy and Boornazian's conclusion EXCEPT

a. the non-uniformity of atmospheric clarity
b. the calculations used to determine the sun's horizontal diameter
c. atmospheric distortion even during periods of clear skies
d. the sheer intensity of the sun's radiance
e. the comparatively brief period of time their study covers

4 
 4. Which of the following, if true, would most seriously undermine the argument put forth by Eddy and Boornazian?

A. The apparent image size of the sun is distorted by atmospheric moisture, which can fluctuate from year to year.
B. Eddy and Boornazian's theory is corroborated by data collected during solar eclipses.
C. Not all heliologists agree that the duration of solar eclipses provides information pertinent to measuring the sun's diameter.
D. Mercury's orbit is erratic and has changed radically on several occasions over the last two centuries.
E. Image measurements of the moon taken from the earth's surface indicate that its size has not changed in the last 200 years.

5 
 5. The passage suggests that which of the following statements, if true, would be most useful in corroborating solar image measurements?

A. Image measurements are taken simultaneously from two different locations.
B. Image measurements are recorded while wearing special goggles that cut down on the sun's brilliance.
C. Light refraction measurement tables for atmospheric gases are developed.
D. Climatic variations are minimized by citing image measurement stations in the desert.
E. Image measurements are made by solar radiation-proofed instruments on satellites orbiting above the earth's atmosphere.

6 
 6. Which of the following statements, if true, would best support the conclusion that the sun's shrinkage is less than Eddy and Boornazian had reported?

A. Solar eclipses occur on a irregular basis, providing less frequent data collection opportunities than image measurement does.
B. A third statistical check, the amount of UV hitting the earth's surface, corroborates the findings of eclipse duration.
C. Solar eclipses are a phenomenon that have been recorded by modern scientists and ancient astronomers alike.
D. Although Mercury's transit has been recorded for centuries, earlier scientific instruments lacked the precision necessary to make accurate observations.
E. Eddy and Boornazian developed a sophisticated computer model to compensate for atmospheric variations during image measurements.

RC Butler 2021  -  Practice Two RC Questions Everyday.   
Passage # 252 Date: 25-Jun-2021
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roadrunner · Answer

1. The author argues that Eddy and Boornazian have

a. misrepresented experimental results in order to gain support for their conclusions
b. incorrectly surmised that the sun's diameter is independent of Mercury's orbit
 c. probably drawn an incorrect conclusion due to their reliance on unreliable data 
d. made several noteworthy breakthroughs in the field of solar measurement
e. wilfully ignored the existence of data pertaining to the duration of solar eclipses

2. According to the author, evidence that the sun is shrinking only at a negligible rate is based on

I. measurement of the length of solar eclipses
II. measurement of the time during which Mercury can be observed crossing the sun's path
III. daily measurements of the sun's image

a. I only
b. II only
c. III only
 e. I and II only 
f. I, II and III
 Only I and II is used to support that sun is shrinking at a negligible rate

3. It can be inferred from the passage that all of the following cast doubt on Eddy and Boornazian's conclusion EXCEPT

a. the non-uniformity of atmospheric clarity
 b. the calculations used to determine the sun's horizontal diameter 
c. atmospheric distortion even during periods of clear skies
d. the sheer intensity of the sun's radiance
e. the comparatively brief period of time their study covers
 Author never questioned calculations, but input data of those calculations.

MaheshDuggirala · Answer

can anyone explain how to eliminate Option D in the 3rd question.

aragonn · Answer

P1 - a theory is given by 2 guys.
P2 - a flaw in theory and how to improve.
P3 - final verdict far less then estimation.

1. The author argues that Eddy and Boornazian have

c. probably drawn an incorrect conclusion due to their reliance on unreliable data - yes

rest all the answer are too broad.
--------------------------------------------------
2. According to the author, evidence that the sun is shrinking only at a negligible rate is based on
P3
I. measurement of the length of solar eclipses - y
II. measurement of the time during which Mercury can be observed crossing the sun's path - y
III. daily measurements of the sun's image - not mentioned.

a. I only 
b. II only 
c. III only 
d. I and II only 
e. I, II and III
----------------------------------------------------
3. It can be inferred from the passage that all of the following cast doubt on Eddy and Boornazian's conclusion EXCEPT

a. the non-uniformity of atmospheric clarity - "the imperfect and variable transparency of the earth’s atmosphere"
b. the calculations used to determine the sun's horizontal diameter - not mentioned
c. atmospheric distortion even during periods of clear skies - "the imperfect and variable transparency of the earth’s atmosphere"
d. the sheer intensity of the sun's radiance - "the brilliance of the sun’s disk"
e. the comparatively brief period of time their study covers - as it mentioned in P2, they must observed for a longer duration.

MaheshDuggirala  - i have tried to explain Q3, let me know if you need more clarity.

teja@6091 · Answer

3. It can be inferred from the passage that all of the following cast doubt on Eddy and Boornazian's conclusion EXCEPT

a. the non-uniformity of atmospheric clarity--- the imperfect and variable transparency of the earth’s atmosphere Eliminated

b. the calculations used to determine the sun's horizontal diameter

c. atmospheric distortion even during periods of clear skies-- -the imperfect and variable transparency of the earth’s atmosphere Eliminated

d. the sheer intensity of the sun's radiance---- - the brilliance of the sun’s disk (eliminated )

e. the comparatively brief period of time their study covers

stuck between B and E.Kindly anyone help me in eliminating Answer E
AkshdeepS,workout--help me

aragonn · Answer

Lets observe following lines.
last sentence of P2 - roughly twice the number of years covered by the data used by Eddy and Boornazian.
or 1st sentence of P3 - When the observations of total solar eclipses over the past three centuries are analyzed

we can term for a longer duration observation in final study. This way we can eliminate E. B is the best answer.

quyanhle24 · Answer

You can eliminate choice D in question 3 by referring to the first sentence of the 2nd paragraph.

Heliologists contend that the brilliance of the sun’s disk, and the imperfect and variable transparency of the earth’s atmosphere, make observations from the earth’s surface unreliable.

"The brilliance of the sun's disk", refers to the intensity of the sun's radiance.

proudcrimson · Answer

Can someone help with question no. 6?

Posted from my mobile device

GAngstA · Answer

5th and 6th question please

Sajjad1994 · Answer

Explanation

6. Which of the following statements, if true, would best support the conclusion that the sun's shrinkage is less than Eddy and Boornazian had reported?

Difficulty Level:   700

Explanation

The only answer option C makes this question a hard one, all other three options are easy to eliminate. This question is based on paragraph 2. Let's read the answer choices one by one.

A. Solar eclipses occur on an irregular basis, providing less frequent data collection opportunities than image measurement does.

This answer choice is saying that the duration of solar eclipses is the wrong indication of solar measurement. It opposing to what is discussed in paragraph 2 hence this option is the opposite.

B. A third statistical check, the amount of UV hitting the earth's surface, corroborates the findings of eclipse duration.

This is supporting to what is written in the second paragraph, let's read it.

A  better source  of data regarding solar shrinkage is the  duration of total solar eclipses , while a  second statistically independent check  is provided by the time the planet Mercury is visible against the solar disk. These observations allow monitoring of changes in the sun’s diameter at reasonably regular intervals back to about the start of the 18th century

This option verifying that the duration of solar eclipses is a better way to measure the sun's diameter. This is correct.

C. Solar eclipses are a phenomenon that has been recorded by modern scientists and ancient astronomers alike.

This is a trap answer, this option only tells us that Solar eclipses are a phenomenon that has been recorded by modern scientists but it didn't tell us whether it is reliable or not. Hence this is incorrect

D. Although Mercury's transit has been recorded for centuries, earlier scientific instruments lacked the precision necessary to make accurate observations.

This is providing unrelated information having no connection with the question.

E. Eddy and Boornazian developed a sophisticated computer model to compensate for atmospheric variations during image measurements.

This is rather opposite indicating that Eddy and Boornazian's calculations are better and reliable.

Answer: B

Sajjad1994 · Answer

Explanation 5. The passage suggests that which of the following statements, if true, would be most useful in corroborating solar image measurements? Difficulty Level: 600 Explanation This is a comparatively easy question because of the answer choices other than the correct one, they are so indicating that they are wrong. Let's not forget what is question is asking for. Read the answer choices one by one. A. Image measurements are taken simultaneously from two different locations. Out of context. Nothing is there about the two locations. B. Image measurements are recorded while wearing special goggles that cut down on the sun's brilliance. Special googles? wow. Out of context. C. Light refraction measurement tables for atmospheric gases are developed. Out of context. D. Climatic variations are minimized by citing image measurement stations in the desert. It is very little better than the other three options but still out of context. E. Image measurements are made by solar radiation-proofed instruments on satellites orbiting above the earth's atmosphere. This is the answer not because it is perfect but because it is less flawed than the other four options. Answer: E For the explanation of question number 6 click on the link given below https://gmatclub.com/forum/in-1979-john ... l#p2812622 Thank you

In 1979, John A. Eddy of the High Altitude Observatory and Aram A. Bo

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In 1979, John A. Eddy of the High Altitude Observatory and Aram A. Bo

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