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# Until recently many astronomers believed that asteroids travel about

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Intern
Joined: 06 Jul 2015
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06 Jul 2015, 14:41
3
Discussed here
https://gmatclub.com/forum/until-recent ... 58590.html

Until recently many astronomers believed that asteroids travel about the solar system unaccompanied by satellites. These astronomers assumed this because they considered asteroidsatellite systems inherently unstable. Theoreticians could have told them otherwise: even minuscule bodies in the solar system can theoretically have satellites, as long as everything is in proper scale. If a bowling ball were orbiting about the Sun in the asteroid belt, it could have a pebble orbiting it as far away as a few hundred radii (or about 50 meters) without losing the pebble to the Sun’s gravitational pull.

Observations now suggest that asteroid satellites may exist not only in theory but also in reality. Several astronomers have noticed, while watching asteroids pass briefly in front of stars, that something besides the known asteroid sometimes blocks out the star as well. Is that something a satellite?

The most convincing such report concerns the asteroid Herculina, which was due to pass in front of a star in 1978. Astronomers waiting for the predicted event found not just one occultation, or eclipse, of the star, but two distinct drops in brightness. One was the predicted occultation, exactly on time. The other, lasting about five seconds, preceded the predicted event by about two minutes. The presence of a secondary body near Herculina thus seemed strongly indicated. To cause the secondary occultation, an unseen satellite would have to be about 45 kilometers in diameter, a quarter of the size of Herculina, and at a distance of 990 kilometers from the asteroid at the time. These values are within theoretical bounds, and such an asteroid-satellite pair could be stable.

With the Herculina event, apparent secondary occultations became “respectable”—and more commonly reported. In fact, so common did reports of secondary events become that they are now simply too numerous for all of them to be accurate. Even if every asteroid has as many satellites as can be fitted around it without an undue number of collisions, only one in every hundred primary occultations would be accompanied by a secondary event (one in every thousand if asteroidal satellite systems resembled those of the planets).

Yet even astronomers who find the case for asteroid satellites unconvincing at present say they would change their minds if a photoelectric record were made of a well-behaved secondary event. By “well-behaved” they mean that during occultation the observed brightness must drop sharply as the star winks out and must rise sharply as it reappears from behind the obstructing object, but the brightness during the secondary occultation must drop to that of the asteroid, no higher and no lower. This would make it extremely unlikely that an airplane or a glitch in the instruments was masquerading as an occulting body.

1. According to the passage, the attitude of astronomers toward asteroid satellites since the Herculina event can best be described as

(A) open-mindedness combined with a concern for rigorous standards of proof
(B) contempt for and impatience with the position held by theoreticians
(C) bemusement at a chaotic mix of theory, inadequate or spurious data, and calls for scientific rigor
(D) hardheaded skepticism, implying rejection of all data not recorded automatically by state-ofthe-art instruments
(E) admiration for the methodical process by which science progresses from initial hypothesis to incontrovertible proof

2. The author implies that which one of the following was true prior to reports of the Herculina event?

(A) Since no good theoretical model existed, all claims that reports of secondary occultations were common were disputed.
(B) Some of the reported observations of secondary occultations were actually observations of collisions of satellites with one another.
(C) If there were observations of phenomena exactly like the phenomena now labeled secondary occultations, astronomers were less likely then to have reported such observations.
(D) The prevailing standards concerning what to classify as a well-behaved secondary event were less stringent than they are now.
(E) Astronomers were eager to publish their observations of occultations of stars by satellites of asteroids.

3. The information presented in the passage implies which one of the following about the frequency of reports of secondary occultations after the Herculina event?

(A) The percentage of reports of primaryoccultations that also included reports of secondary occultations increased tenfold compared to the time before the Herculina event.
(B) Primary occultations by asteroids were reported to have been accompanied by secondary occultations in about one out of every thousand cases.
(C) The absolute number of reports of secondary occultations increased tenfold compared to the time before the Herculina event.
(D) Primary occultations by asteroids were reported to have been accompanied by secondary occultations in more than one out of every hundred cases.
(E) In more than one out of every hundred cases, primary occultations were reported to have been accompanied by more than one secondary occultation.

4. The primary purpose of the passage is to

(A) cast doubt on existing reports of secondary occultations of stars
(B) describe experimental efforts by astronomers to separate theoretically believable observations of satellites of asteroids from spurious ones
(C) review the development of ideas among astronomers about whether or not satellites of asteroids exist
(D) bring a theoretician’s perspective to bear on an incomplete discussion of satellites of asteroids
(E) illustrate the limits of reasonable speculation concerning the occultation of stars

Senior Manager
Joined: 02 Oct 2009
Posts: 381
GMAT 1: 530 Q47 V17
GMAT 2: 710 Q50 V36

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06 Jul 2015, 20:21
1
Pretty decent Passage. good for Practice. Got all the questions correct.
Intern
Joined: 22 Jul 2014
Posts: 14
Concentration: Social Entrepreneurship, Sustainability

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17 Sep 2015, 23:01
(1) A
A. The opening line of the passage tells us that the astronomers were skeptical about astroid satellite systems ( "until recently many...."). In the 2nd para, the existence of such system became "respectable" (post Herculina). This marks a change in attitude. However, astronomers are not completely convinced. They are willing to change their minds if more proof is available.
B. The astronomers show no dislike for theoreticians or with the position held by theoreticians. In fact, astronomical observations are cross checked with theoretical values to provide more verifiable conclusion.
C. The astronomers are not bemused at the chaotic mix of theory. What was stated by the theory is in fact observed the the astronomers & the collective output of both parties have led to a change in the astronomer's attitude. However, some of them call for more scientific data.
D. As stated in (A), skepticism transitioned into open mindedness. Therefore, choice D is wrong.
E. As stated in the last para, the astronomers call for verifiable scientific data to consider the hypothesis as true. Incontrovertible proof is yet to be established.

(2) C
A. Theories were eventually backed by observations as true. Secondary occultations gave support to the hypothesis developed by theoreticians.
B. Nothing has been mentioned to link secondary occultations to collisions.
C. Para e begins, "Observations NOW suggest....exist not only in theory....also reality" meaning prior observations of such occultations were less likely to have been reported.
D. Prior to Heruclian, "well-behaved" secondary event standards did not exist, therefore there were no "prevailing standards"
E. Astronomers observed secondary occultations..this changed their views on asteroid-satellite system..Were they eager to publish it? We cannot infer.

(3) D
A. % Increased 10X compared to the time prior to Herculina. Not implied. Especially since we have not been given any no. of Sec.Occ. prior to Herculina or post.
B. The only time 1/1000 case is mentioned is in para 2...to existence of asteroid satellite system if it resembles those of the planets.
C. As stated in (A), we do have have any "10X" or "absolute" number
D. Para 2 clearly states ...1/100 asteroid would be accompanied by a secondary event.
E. "more than one secondary occultaion'? No such thing has been mentioned. Para2

(4) C
A. Firstly, reports of secondary occultations are recent findings not existent. Secondly, such findings have not be subjected to doubt but accepted with some reservations
B. Separate theoretical hypothesis to spurious ones? Experimental efforts? Astronomers simply found new revelations that gave some traction to the hypothesis
C. The concept of asteroid-satellite system has seen incremental gains. The author reviews these development.
D. The passage weighs in the astronomers' views on the topic...and introduces the theoretical view..The discussion on the topic has never been incomplete but rather different due to the lack of verifiable data. Subsequent lines show that with the findings of such data..the discussion leads to a more substantial , if not conclusive, end.
E. In the 3rd para, astronomers seek data from experimental observation to consider the hypothesis as true. But this alone is not the primary purpose of the passage.
Tuck School Moderator
Status: Valar Dohaeris
Joined: 31 Aug 2016
Posts: 301
GMAT 1: 700 Q49 V37

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15 Feb 2019, 09:56
1
its a LSAT passage. Please modify the tags.
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Re: Until recently many astronomers believed that asteroids travel about   [#permalink] 15 Feb 2019, 09:56
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