Set 4

SAMPLE READING TEST QUESTIONS

DIRECTIONS: The passage in this test is followed by several questions. After reading the passage, choose the best answer to each question and WRITE THE ANSWER IN YOUR NOTEBOOK. You may refer to the passage as often as necessary. To have the questions open in a new browser window, CLICK HERE After you have finished answering ALL of the questions, check your answers by clicking on the letter you have chosen. COUNT THE NUMBER OF ANSWERS YOU GOT CORRECT ON THE FIRST TRY, MARK IT DOWN, AND TELL ME THE SCORE

NATURAL SCIENCE: This passage is adapted from Mark
Littman's Planets Beyond: Discovering the Outer Solar System
(©1990 by John Wiley & Sons).

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[From the surface of the planet Pluto,] we look up at Charon in the sky, 20 times closer to Pluto than our Moon is to Earth. It is an impressive sight. Charon may rank twelfth in size among moons in the solar system, but it is so close to Pluto—only 11,650 miles (18,800 kilometers) above Pluto's equator—that it appears larger than any other moon appears from the surface of its planet. Charon covers almost 4 degrees in Pluto's sky—eight times as wide as our Moon appears from Earth. On our planet, you can hold a pea out at arm's length and completely eclipse our Moon. On Pluto, to block Charon from view, you would need a billiard ball.      It was no surprise that Charon rotates in the same period of time as it revolves so that it always presents the same hemisphere to Pluto. All the inner satellites and all the major satellites in the solar system have syn- chronous rotation and revolution because they are tidally coupled to their planets. A planet's gravity cre- ates a slight tidal bulge in its moons and pulls on that bulge so that the moons cannot turn it away from the planet. One side of the satellite always faces the planet and the other side always faces away while the planet rotates rapidly, so that the moon rises and sets for all parts of the planet.      But Pluto furnished a surprise. Pluto and Charon are so close to twins in size and so close together that Charon's gravity induces a bulge in Pluto. The bulge is great enough that Pluto is tidally coupled to Charon just as Charon is tidally coupled to Pluto. Thus, Pluto always shows the same face to Charon just as Charon always shows the same face to Pluto. It is the only example of mutual tidal coupling in the solar system. The result is that for an astronaut standing on Pluto, Charon is either always visible or never visible.      The shadows we see on Charon reveal an uneven, cratered landscape. Like Pluto, Charon is light gray, although somewhat darker and more even in color than Pluto, as was known from measurements made from Earth using the Pluto-Charon eclipses. The very slightly reddish brown hue of Pluto is missing from Charon—or at least from Charon's Pluto-facing side, that is the only side we get to see from the surface of Pluto. Missing too from Charon is the methane frost which partially covers Pluto. With Charon's smaller mass and therefore weaker gravity, whatever methane ice there was at the surface has evaporated. Perhaps this in part explains why Charon is less reflective. The escaping methane has exposed frozen water to view.      On Earth, we are used to the rising and setting of the Sun, Moon, and stars as our planet turns. On Pluto, the Sun rises and sets, if somewhat slowly, but Charon stays fixed in the sky. It never rises or sets, thanks to tidal coupling. As Charon revolves once around Pluto in 6.4 days, Pluto spins once around on its axis in that same period of time. The result is that Charon hangs almost stationary in the sky while the Sun and stars glide slowly past in the background. Because Charon is so large in the sky, stars are frequently blocked from view. These stellar occultations are the only eclipses visible during the 120-year gap between seasons of solar and lunar eclipses.      From the vantage point of Earth, Pluto and Charon pass in front of and behind one another very rarely. The Earth experiences solar and lunar eclipses at least four times and sometimes as many as seven times a year. Because of Pluto's axial tilt and Charon's position over Pluto's equator, the pair go for almost 120 years without their shadows ever falling upon one another. Then, in a period roughly six years long, Charon's orbit is nearly edge on to Earth and every 6.39-day orbit Charon makes carries it across the face of Pluto and then around behind Pluto. The result is an eclipse frenzy. Serendipitously, that eclipse season began in 1985, soon after Charon was discovered.      During an eclipse of the Sun on Pluto, Charon would look like a giant dark hole in the sky, marked only by the absence of stars. It would be dark but not black because it would be illuminated by reflected light from Pluto. The corona—the outer atmosphere of the Sun, which makes solar eclipses seen from Earth so beautiful—would be visible only just after the Sun van- ished and just before it reappeared. At mid-eclipse, the disk of Charon covers the entire orbit of the Earth. The corona is far too faint at that distance from the Sun to peer around the edges of Charon.

1.	The passage states that Charon never sets because of: A. an eclipse frenzy. B. stellar occultations. C. tidal coupling. D. escaping methane.

2.	The passage asserts that Charon's relationship with Pluto is unique in our solar system in regard to: F. frequency of eclipses. G. mutual tidal coupling. H. synchronous rotation. J. axial tilt.

3.

The main point of the first paragraph is that: A. Charon is more similar to Earth's moon than you might expect. B. Charon is surprisingly similar to Pluto. C. Charon's closeness to Pluto makes it appear huge from the surface of its planet. D. in terms of size, the Earth is to Pluto as a billiard ball is to a pea.

4.	As it is defined in the passage, the Sun's corona is:   I. the Sun's outer atmosphere.   II. illuminated by reflected light.   III. reflected light. F. I only G. III only H. I and III only J. I, II, and III

5.	The long spans of time that elapse between periods of eclipse frenzy on Pluto are the result of:   I. Pluto's axial tilt.   II. methane escaping Charon's surface.   III. Charon's position relative to Pluto's equator. A. I only B. III only C. I and II only D. I and III only

6.	The passage asserts that one feature of Pluto that is lacking on Charon is: F. escaping methane. G. noticeable gravity. H. a cratered landscape. J. methane frost.

7.	It can reasonably be deduced from the first paragraph that the number of degrees in the Earth's sky taken up by our Moon is roughly: A. 0.5 degree. B. 1.0 degree. C. 4.0 degrees. D. 8.0 degrees.

8.	The passage states that the methane ice on Charon evaporated because of that moon's:   I. smaller mass.   II. weaker gravity.   III. axial tilt. F. II only G. I and II only H. I and III only J. I, II, and III

9.

The passage states that all major satellites in our solar system have in common the fact that they have: A. axial tilt and somewhat noticeable mutual tidal coupling. B. closer proximity to their respective planets than our Moon has to Earth. C. synchronous rotation caused by tidal coupling to their planets. D. periods of eclipse that are frenzied and also serendipitous.

10.

The passage suggests that the discovery of Charon was made even more interesting for scientists because that discovery coincided with: F. the discovery of the synchronous rotation of satellites. G. a large number of eclipses occurring on Pluto. H. the realization that our Moon is identical to Charon. J. a demonstration of tidal coupling by Earth and its Moon.

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