PSAT Reading Practice Question 564

Question: 564

This passage is adapted from a 2013 article about Halley's Comet.
Much like Old Faithful at Yellowstone
National Park—by far the most well-known
of the American geysers—Halley's Comet
is neither the most visually brilliant nor the
05largest of its kind; its renown derives from
the dependable frequency with which it can
be observed. Halley's falls into a category
called Great Comets, which are those that
become bright enough during their passage
10near Earth to be observed by the naked eye.
Predicting whether or not a comet will be
great has proven to be a treacherous task
even for the most talented of astronomers
and astrophysicists. The comet must pass
15through a relatively small expanse of space
near enough to the Sun to reflect a large
amount of light but remain close enough
to Earth for the light to reach and penetrate
our atmosphere. Moreover, it is thought
20that a Great Comet must possess a large and
active nucleus, though the exact physics of
comet nuclei—which consist of dust, ice, and
perhaps particulate minerals—are still poorly
understood. Even so, comets meeting these
25criteria have on occasion failed to achieve
greatness. To date, the most recent Great
Comet was C/2006 P1, which appeared in
January 2007 and was the brightest in more
than 40 years.
30The intrinsic difficulty of predicting a
comet's greatness makes the consistency
of Halley's visibility all the more remarkable.
Most Great Comets will pass near Earth
only once every several thousand years,
35while Halley's does so on a cycle of about 75
years—making it the only Great Comet with
the potential to appear twice in a human
lifetime. With an eccentricity of 0.967, the orbit
of Halley's Comet is extremely elliptical; at
40one end of its major axis, Halley's is roughly
the same distance from the Sun as Pluto. At
the other end, it passes between the orbits
of Mercury and Venus. The highly elliptic
character of Halley's orbit means that, apart
45from having one of the highest velocities of
any body in our solar system, it passes near
Earth both during its approach and its return
from the Sun. Though becoming visible during
only one of these passes, the two near
50points of the orbit make Halley's the parent
body of two annual meteor showers: the Eta
Aquariids in early May and Orionids of late
October.
Though humans have likely marveled at
55the spectacle of Halley's Comet for thousands
of years (the Talmudic astronomers of
the 1st century describe a star that appears
once every 70 years to wreak havoc on nautical
navigation), it was little more than 300
60years ago that Edmond Halley—a friend of Sir
Isaac Newton's—used Newton's newly conceived
laws of gravity to explain the motion
and predict the periodicity of comets. By
using these equations in tandem with historical
65records, Halley surmised that the comets
observed in 1531 by German Humanist
Petrus Apianus, in 1607 by Johannes Kepler,
and by himself and Newton in 1683 were one
and the same. Moreover, he predicted its
70return in 1758. Halley passed away in January
1742 at the age of 85, nearly 16 years to the
day short of seeing his prediction confirmed
firsthand. Yet, in an almost poetic cyclicity,
Halley's Comet—the periodicity of which
75Halley had derived from the observations of
two German astronomers—was observed
and documented by German farmer and
amateur astronomer Johann Palitzsch on
Christmas Day, 1758. The confirmation of
80Halley's theory constituted the first occasion
in which Western science had proven that
any bodies apart from planets orbit the Sun.
Halley's Comet has been visible in our sky
just three times since Palistzch's observation,
85but it will return again sometime in the summer
of 2061.

Which choice provides the best evidence for the answer to the previous question?

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