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Astronomy: A Beginner's Guide to the Universe, 7e (Chaisson/McMillan)
Chapter 1 The Copernican Revolution: The Birth of Modern Science
1) According to Newton's third law, when the Voyager probes passed Jupiter in 1979, they exerted exactly the same force on Jupiter as the giant planet did on them.
Answer: TRUE
Diff: 3
Section Ref.: 1.4
2) Compared to when it was on the surface, a satellite in an orbit whose radius is about 4 times the Earth's radius will experience about 1/16 the force due to the Earth's gravity.
Answer: TRUE
Diff: 3
Section Ref.: 1.4
3) According to Newton's second law, if you double the force acting on a body, the acceleration will double.
Answer: TRUE
Diff: 2
Section Ref.: 1.4
4) According to Newton's first law, an object traveling in a circle does not have a force acting on it.
Answer: FALSE
Diff: 1
Section Ref.: 1.4
5) Kepler's third law allows us to find the average distance to a planet from observing its period of rotation on its axis.
Answer: FALSE
Diff: 2
Section Ref.: 1.3
6) According to Kepler's third law, if you know the planet's orbital period, you can find its average distance from the Sun.
Answer: TRUE
Diff: 2
Section Ref.: 1.3
7) A planet (or comet) will speed up as it approaches the Sun.
Answer: TRUE
Diff: 2
Section Ref.: 1.3
8) Kepler found the orbits of planets are ellipses, not circles.
Answer: TRUE
Diff: 1
Section Ref.: 1.3
9) Kepler relied heavily on the telescopic observations of Galileo in developing his laws of planetary motion.
Answer: FALSE
Diff: 2
Section Ref.: 1.3
10) Kepler's third law relates the square of the planet's orbital period in years to the cube of its average distance from the Sun in astronomical units.
Answer: TRUE
Diff: 1
Section Ref.: 1.3
11) Among Galileo's discoveries with his telescope were sunspots.
Answer: TRUE
Diff: 1
Section Ref.: 1.2
12) Galileo's observations of the entire phase cycle of Venus proved that Ptolemy's epicycles could not be correct in keeping Venus between us and the Sun.
Answer: TRUE
Diff: 1
Section Ref.: 1.2
13) According to Copernicus, retrograde motion occurs at opposition for the outer planets.
Answer: TRUE
Diff: 2
Section Ref.: 1.1
14) In Ptolemy's geocentric model, the planet's motion along its deferent is all that is needed to understand retrograde motion.
Answer: FALSE
Diff: 1
Section Ref.: 1.1
15) Copernicus believed the Earth was the center of all celestial motion.
Answer: FALSE
Diff: 1
Section Ref.: 1.1
16) In Ptolemy's geocentric model, retrograde motion occurs when the planet is closest to us, on the inside portion of the
A) deferent.
B) ellipse.
C) epicycle.
D) equant.
E) ecliptic.
Answer: C
Diff: 1
Section Ref.: 1.1
17) In Ptolemy's geocentric model, the normal eastward motion of the planets was along
A) a deferent.
B) an epicycle.
C) a retrograde loop.
D) an ellipse.
E) the equant.
Answer: A
Diff: 1
Section Ref.: 1.1
18) Copernicus' Heliocentric theory explains that
A) planetary orbits are elliptical in shape.
B) the Sun lies at one focus of an ellipse.
C) Venus retrogrades when she overtakes us at inferior conjunction.
D) all planets lie between the Sun and Earth.
E) Mars will retrograde when it reaches a certain position on its epicycle.
Answer: C
Diff: 2
Section Ref.: 1.1
19) According to Copernicus, retrograde motion for Venus must occur around
A) inferior conjunction, when it passes between us and the Sun.
B) quadrature, when the planet is 90 degrees away from the Sun.
C) greatest elongation, when the planet is farthest from the Sun.
D) superior conjunction, when the planet is on the far side of the Sun.
E) opposition, when the planet lies opposite the Sun in the sky.
Answer: A
Diff: 2
Section Ref.: 1.1
20) According to Copernicus, the retrograde motion for Mars must occur
A) at inferior conjunction, when Mars laps the Earth and passes between us and the Sun.
B) at superior conjunction, when Mars lies on the far side of the Sun.
C) at quadrature, when Mars lies exactly 90 degrees east or west of the Sun.
D) at greatest elongation, when Mars can get up to 47 degrees from the Sun.
E) at opposition, when the Earth overtakes Mars and passes between Mars and the Sun.
Answer: E
Diff: 2
Section Ref.: 1.1
21) A fatal flaw with Ptolemy's model is its inability to predict the observed phases of
A) the Sun during an eclipse.
B) the Moon in its monthly cycle.
C) Mercury and Venus.
D) Mars and Jupiter.
E) Jupiter and Saturn.
Answer: C
Diff: 2
Section Ref.: 1.2
22) Which of these was NOT seen telescopically by Galileo?
A) sunspots
B) Venus' phase cycle
C) Four moons around Jupiter
D) stellar parallax
E) craters and mare on the Moon
Answer: D
Diff: 1
Section Ref.: 1.2
23) Which of these observations of Galileo refuted Ptolemy's epicycles?
A) the complete cycle of Venus' phases
B) the rotation of sunspots across the Sun's surface
C) the revolution of Jupiter's moons around it
D) the craters on the Moon
E) the visibility of many more stars with the telescope
Answer: A
Diff: 2
Section Ref.: 1.2
24) Galileo found the rotation period of the Sun was approximately
A) a day.
B) a week.
C) a month.
D) three months.
E) a year.
Answer: C
Diff: 3
Section Ref.: 1.2
25) Tycho Brahe's contribution to Kepler's Laws of Planetary Motion were
A) his detailed and accurate observations of the planets' positions.
B) his observations of Jupiter's moons.
C) a mathematical explanation of epicycles.
D) a precise lunar calendar.
E) the correct explanation of lunar phases.
Answer: A
Diff: 1
Section Ref.: 1.3
26) Kepler's first law worked, where Copernicus' original heliocentric model failed, because Kepler described the orbits as
A) elliptical, not circular.
B) much larger than Copernicus had envisioned.
C) around the Sun, not the Earth.
D) being on equants instead of epicycles.
E) complex, with epicycles to account for retrograde motions.
Answer: A
Diff: 1
Section Ref.: 1.3
27) When a planet's orbit takes it closest to the Sun, it's called
A) vernal equinox.
B) aphelion.
C) perihelion.
D) crossing the ecliptic.
E) none of these; a planet's distance from the Sun never changes.
Answer: C
Diff: 2
Section Ref.: 1.3
28) A planet whose distance from the Sun is 3 AU would have an orbital period of how many Earth-years?
A) 3
B) 
C) 
D) 9
E) 81
Answer: B
Diff: 3
Section Ref.: 1.3
29) The force of gravity varies with the
A) product of the two masses.
B) inverse of the distance separating the two bodies.
C) inverse square of the distance separating the two bodies.
D) Both A and B are correct.
E) Both A and C are correct.
Answer: E
Diff: 1
Section Ref.: 1.4
30) A circular orbit would have an eccentricity of
A) 0.
B) between 0 and 0.5.
C) between 0.5 and 1.
D) exactly 1.0.
E) infinity.
Answer: A
Diff: 1
Section Ref.: 1.4
31) How much stronger is the gravitational pull of the Sun on Earth, at 1 AU, than it is on Saturn at 10 AU?
A) 5
B) 10
C) 25
D) 100
E) 250
Answer: D
Diff: 3
Section Ref.: 1.4
32) If the distance between two asteroids is doubled, the gravitational force they exert on each other will
A) also be doubled.
B) be half as great.
C) be one fourth as great.
D) will be 1/16 as great.
E) be four times greater.
Answer: C
Diff: 3
Section Ref.: 1.4
33) Because he failed to observe stellar ________, Aristotle wrongly concluded we could not be in orbit around the Sun.
Answer: parallax
Diff: 1
Section Ref.: 1.1
34) The mean distance between the Earth and Sun is called the ________.
Answer: astronomical unit
Diff: 1
Section Ref.: 1.1
35) Ptolemy's model was ________, with the Earth fixed in the center of the universe.
Answer: geocentric
Diff: 1
Section Ref.: 1.1
36) The model of ________ used circular deferents and epicycles in a geocentric universe to explain planetary motions.
Answer: Ptolemy
Diff: 1
Section Ref.: 1.1
37) The time for a planet to revolve around the Sun is its ________.
Answer: orbital period or year
Diff: 2
Section Ref.: 1.1
38) When Earth overtakes Mars, the outer planet retrogrades near ________.
Answer: opposition
Diff: 2
Section Ref.: 1.1
39) The "guest star" observed by the Chinese in 1054 is now known to have been a ________.
Answer: supernova
Diff: 2
Section Ref.: 1.1
40) Galileo's discovery of four moons orbiting ________ provided new support for the ideas of Copernicus.
Answer: Jupiter
Diff: 2
Section Ref.: 1.2
41) For Galileo, the observation of the phases of ________ proved that Ptolemy's geocentric model with epicycles was wrong.
Answer: Venus
Diff: 2
Section Ref.: 1.2
42) The ________ hypothesis is that the Earth does not occupy any special place in the universe.
Answer: Copernican
Diff: 3
Section Ref.: 1.2
43) The three laws of planetary motion by ________ allowed us to predict planetary motion.
Answer: Kepler
Diff: 1
Section Ref.: 1.3
44) While both Ptolemy and Copernicus assumed all orbits were ________, Kepler's first law corrected this and made planetary motion predictable.
Answer: circles
Diff: 1
Section Ref.: 1.3
45) Kepler's theories were based on the very accurate observations made by ________.
Answer: Tycho Brahe
Diff: 2
Section Ref.: 1.3
46) According to Newton's laws, the planets orbit the Sun due to ________.
Answer: gravity
Diff: 1
Section Ref.: 1.4
47) According to Newton, the gravity of the ________ is needed to explain planetary orbits.
Answer: Sun
Diff: 1
Section Ref.: 1.4
48) In Newton's first law, the ________ of a body causes it to resist changes in its motion
Answer: inertia
Diff: 1
Section Ref.: 1.4
49) According to Newton's second law, when the same force acts on two bodies, the body with the larger mass will have the ________ acceleration.
Answer: smaller
Diff: 1
Section Ref.: 1.4
50) Newton found that gravity varied with the ________ of the distance between the two bodies pulling on each other.
Answer: inverse square
Diff: 2
Section Ref.: 1.4
51) How did Ptolemy explain the retrograde motion of Venus?
Answer: The epicycle for both Mercury and Venus is always centered on the Earth-Sun line, so they always orbit between us and the Sun.
Diff: 3
Section Ref.: 1.1
52) How did Ptolemy explain the retrograde motion of Mars?
Answer: Mars will retrograde on the inner portion of its epicycle, when it is closest to us and its motion on the epicycle is more obvious than its motion along its deferent.
Diff: 3
Section Ref.: 1.1
53) What "imperfections" on the Moon were visible to Galileo's telescopes?
Answer: Impact craters, mountains, and dark lava flows, or mare.
Diff: 2
Section Ref.: 1.2
54) What is meant by the astronomical unit?
Answer: The astronomical unit, or AU, is the mean distance between the Earth and Sun.
Diff: 2
Section Ref.: 1.2
55) How did Tycho's detailed observations of Mars' brightness help show that its orbit could not be circular?
Answer: Tycho noted that at some oppositions, Mars was much brighter than at others, suggesting that Mars must be closer to us when it was brighter.
Diff: 3
Section Ref.: 1.1
56) What did Galileo discover through his telescope when he looked at Jupiter, and how did it refute the Ptolemaic model?
Answer: That Jupiter had four moons in orbit about it, so Earth was not the center of all things. Ptolemy contended that all things move around the Earth.
Diff: 3
Section Ref.: 1.2
57) The speed of light (and radio waves) is 300,000 km/s. How far away is a spacecraft if its radio signal takes 10 minutes to reach Earth?
Answer: 180,000,000 km
Diff: 3
Section Ref.: 1.2
58) What did Galileo discover when looking at the Sun with his telescope, and how did this support Copernicus?
Answer: Sunspots, which rotated across the Sun's face, showing that the Sun was not perfect and it (and Earth) could rotate on its axis.
Diff: 3
Section Ref.: 1.2
59) Explain how the eccentricity describes the shape of an ellipse.
Answer: The higher the eccentricity, the more elongated the oval; a circle has an eccentricity of zero, while very stretched-out comet orbits approach an eccentricity of one.
Diff: 3
Section Ref.: 1.3
60) According to Newton's first law, if a body is moving in the absence of any net external force, describe the continuing motion of the object.
Answer: in a straight line at constant speed forever
Diff: 1
Section Ref.: 1.4
61) How do the two factors (mass and distance) in Newton's law of gravitation each affect the force on the two bodies?
Answer: The greater the masses of the two bodies, the larger their gravity. The farther apart the bodies, the weaker this force, by the inverse square of this distance.
Diff: 2
Section Ref.: 1.4
62) Why do Newton's Laws show a force must be acting on the planets?
Answer: The planets are moving in elliptical orbits (not a straight line). According to First Law, if no force acts on the body, it must move in a straight line. Since the planets do not, there must be a force acting on them.
Diff: 3
Section Ref.: 1.4
63) Why was Copernicus' model much simpler than Ptolemy's?
Answer: To duplicate retrograde motion, Copernicus merely had the planets lapping each other as they revolved around the Sun at varying speeds. Ptolemy needed a complex set of deferents and epicycles to explain retrograde motion in his geocentric model.
Diff: 2
Section Ref.: 1.1
64) Why argument did the Aristotelian school present to reject the concept of Aristarchus that the Earth could be revolving around the Sun? Why was it wrong?
Answer: Aristotle correctly concluded that if the heliocentric model were valid, we should be able to see the closer stars show parallax shift over a six-month interval as we went from one side of the Sun to the other. He failed to detect any such shifting, and thus concluded we could not be moving. Now, with powerful telescopes, we do measure the parallax shifts of the nearby stars, but this is much too tiny to be detected with the naked eye by the ancient Greeks.
Diff: 3
Section Ref.: 1.1
65) How would Ptolemy explain the rising of the Sun? Contrast this to Copernicus' explanation of the same event.
Answer: Ptolemy would say that the celestial sphere rotated westward, carrying the Sun over our eastern horizon. Copernicus said that we, the Earth, rotate eastward once a day, and we turn to see the Sun on our eastern horizon at sunrise.
Diff: 3
Section Ref.: 1.1
66) Explain how the telescopic discoveries of Galileo could be used in support of Copernicus.
Answer: He found spots on the Sun, which moved across its face as the Sun spins; if the Sun could rotate on its axis, so could the Earth. He found craters and mare on the Moon, imperfect against the perception of heavenly perfection described by the Greeks. He noted that Venus showed an entire cycle of phases as it revolved completely around the Sun, not confined to Ptolemy's epicycles always between us and the Sun. He found four moons around Jupiter, moving fastest when closest, and slower farther out in their orbits; this was a model of the Copernicus solar system. He resolved the Milky Way into many faint, distant stars, showing the "Celestial Sphere" of the Greeks was much vaster than Ptolemy had envisioned.
Diff: 3
Section Ref.: 1.2
67) While the Copernican model was simpler than Ptolemy's, it was no more accurate in predicting planetary behavior at first. How did Kepler improve it?
Answer: Like Ptolemy, Copernicus believed all orbits to be perfectly circular; Kepler's ellipses, combined with the heliocentric model, made planetary motion much more predictable.
Diff: 2
Section Ref.: 1.3
68) Explain how Kepler's laws allow us to use the motion of an asteroid to find its average distance from the Sun.
Answer: By watching it long enough to find its period of revolution around the Sun, we can use Kepler's third law to get the average distance by squaring the period in years, then finding the cube root of this value for the average distance of the asteroid from the Sun in astronomical units.
Diff: 3
Section Ref.: 1.3
69) According to Newton's third law, the Voyager probes pulled just as hard on Jupiter as it did on them when they flew past it. Why were they accelerated enough to leave the solar system but Jupiter still is in orbit about the Sun?
Answer: Jupiter was much more massive than the Voyagers, so by the second law, they slowed Jupiter down a tiny bit, but it accelerated the probes so much they escaped the gravity of the Sun itself.
Diff: 3
Section Ref.: 1.4
70) How can astronomers determine the mass of the Sun?
Answer: Using Newton's Laws, we know that gravity keeps the Earth in orbit around the Sun. Since the Earth's path is nearly circular, we can determine the size of the force keeping it on this path. Combining this equation (for centripetal force) with the gravity equation allows astronomers to calculate the Sun's mass.
Diff: 3
Section Ref.: 1.4
Astronomy: A Beginner's Guide to the Universe, 7e (Chaisson/McMillan)
Chapter 0 Charting the Heavens: The Foundations of Astronomy
1) Right ascension in the sky is very similar to latitude on the Earth.
Answer: FALSE
Diff: 1
Section Ref.: 0.1
2) Latitude and right ascension are coordinate systems used to find objects on the celestial sphere.
Answer: FALSE
Diff: 1
Section Ref.: 0.1
3) The celestial sphere is divided into 88 modern constellations.
Answer: TRUE
Diff: 1
Section Ref.: 0.1
4) In the sky, declination is measured in degrees north or south of the celestial equator.
Answer: TRUE
Diff: 1
Section Ref.: 0.1
5) The south celestial pole is located at a declination of -90 degrees.
Answer: TRUE
Diff: 1
Section Ref.: 0.1
6) In general, the brightest star in a given constellation is designated as alpha.
Answer: TRUE
Diff: 1
Section Ref.: 0.1
7) Constellations are close clusters of stars, all at about the same distance from the Sun.
Answer: FALSE
Diff: 1
Section Ref.: 0.1
8) The closest terrestrial analog to hours of right ascension is angle of longitude.
Answer: TRUE
Diff: 2
Section Ref.: 0.1
9) Over 20,000 stars are visible to the naked eye on the darkest, clearest nights.
Answer: FALSE
Diff: 2
Section Ref.: 0.1
10) A star with a right ascension of 2.6 hrs will rise 2.6 hours after the vernal equinox.
Answer: TRUE
Diff: 3
Section Ref.: More Prec. 0.1
11) A tropical year is the same as a sidereal year.
Answer: FALSE
Diff: 1
Section Ref.: 0.2
12) The sidereal day is determined by the Earth's rotation with respect to the stars.
Answer: TRUE
Diff: 1
Section Ref.: 0.2
13) The vernal equinox marks the beginning of spring in the northern hemisphere.
Answer: TRUE
Diff: 1
Section Ref.: 0.2
14) There are 3,600 arc seconds in a degree.
Answer: TRUE
Diff: 2
Section Ref.: More Prec. 0.1
15) An hour of right ascension corresponds to 60 degrees in the sky.
Answer: FALSE
Diff: 2
Section Ref.: 0.2
16) From Earth, the Sun and Moon have about the same angular diameter.
Answer: TRUE
Diff: 1
Section Ref.: 0.2
17) At the solstices, the Sun's declination will be 23.5 degrees from the equator.
Answer: TRUE
Diff: 2
Section Ref.: 0.2
18) At the equinoxes, the declination of the Sun must be zero degrees.
Answer: TRUE
Diff: 2
Section Ref.: 0.2
19) As it orbits the Earth, the Moon appears to move its own diameter (0.5 degrees) eastward every hour against the background stars.
Answer: TRUE
Diff: 3
Section Ref.: 0.3
20) From full moon to third quarter moon takes about a week.
Answer: TRUE
Diff: 1
Section Ref.: 0.3
21) Only people in the Moon's umbral shadow can see a total solar eclipse.
Answer: TRUE
Diff: 1
Section Ref.: 0.3
22) If we are the Moon's penumbra, then we will see a partial lunar eclipse.
Answer: FALSE
Diff: 1
Section Ref.: 0.3
23) There is a solar eclipse of some kind every new moon.
Answer: FALSE
Diff: 1
Section Ref.: 0.3
24) Eighteen days past new moon, the Moon's phase is waning gibbous.
Answer: TRUE
Diff: 2
Section Ref.: 0.3
25) A total solar eclipse will only occur when the new moon is both on the ecliptic and at its greatest distance from Earth.
Answer: FALSE
Diff: 2
Section Ref.: 0.3
26) The larger the parallax shift, the closer an object is to us.
Answer: TRUE
Diff: 1
Section Ref.: 0.4
27) The parallax shift for all stars is very small.
Answer: TRUE
Diff: 1
Section Ref.: 0.4
28) Increasing the baseline will increase the parallax angle.
Answer: TRUE
Diff: 3
Section Ref.: 0.4
29) In the scientific method, it is not necessary to test your theory.
Answer: FALSE
Diff: 1
Section Ref.: 0.5
30) Drawing on Eratosthenes' method, if two observers are due north and south of each other and are separated by 400 km, what is the circumference of their spherical world if they see the same star on their meridian at altitudes of 23 degrees and 47 degrees respectively, and at the exact same time?
A) 2,000 km
B) 4,000 km
C) 6,000 km
D) 8,000 km
E) 12,000 km
Answer: C
Diff: 3
Section Ref.: 0.4
31) The star Wolf 1061 has a parallax of 2.34 arc seconds, while the star Ross 652 has a parallax of 1.70 arc seconds. What can you correctly conclude?
A) Both stars are outside the Milky Way galaxy.
B) Wolf 1061 must have a larger proper motion than Ross 652.
C) Ross 652 must have a larger proper motion than Wolf 1061.
D) Ross 652 is closer to Earth than Wolf 1061.
E) Wolf 1061 is closer to Earth than Ross 652.
Answer: E
Diff: 2
Section Ref.: 0.4
32) The greatest distance above or below the ecliptic the Moon can move is
A) 5.2 degrees.
B) 23.5 degrees.
C) 27.3 degrees.
D) 29.5 degrees.
E) 30 degrees.
Answer: A
Diff: 3
Section Ref.: 0.3
33) In an annular eclipse,
A) the Sun is totally blocked by the Moon.
B) the Moon is totally blocked by the Earth.
C) the Moon appears as a thin, bright ring.
D) the Sun appears as a thin, bright ring.
E) the Sun is partially blocked by the Earth.
Answer: D
Diff: 2
Section Ref.: 0.3
34) If you are in the Earth's umbra on the Earth's surface, then
A) it must be a total solar eclipse.
B) it must be a lunar eclipse of some type.
C) it is night time.
D) the Sun is always visible.
E) the Moon is always visible.
Answer: C
Diff: 2
Section Ref.: 0.3
35) The synodic month is
A) 29.5 days.
B) about two days shorter than the sidereal month.
C) based on the Moon's position relative to the stars.
D) the basis of the year we use in our modern calendar.
E) caused by both the Earth's and Moon's rotations.
Answer: A
Diff: 2
Section Ref.: 0.3
36) If the Moon appears half lit, and is almost overhead about 6:00 AM, its phase is
A) waxing crescent.
B) first quarter.
C) full.
D) third quarter.
E) waning crescent.
Answer: D
Diff: 2
Section Ref.: 0.3
37) If new moon fell on March 2nd, what is the Moon's phase on March 14th?
A) waxing crescent
B) first quarter
C) waxing gibbous
D) full
E) waning crescent
Answer: C
Diff: 2
Section Ref.: 0.3
38) A solar eclipse can only happen during a
A) new moon.
B) solstice.
C) first quarter moon.
D) full moon.
E) perihelion passage of the Sun.
Answer: A
Diff: 2
Section Ref.: 0.3
39) What will occur when the full moon is on the ecliptic?
A) a total lunar eclipse
B) a total solar eclipse
C) a partial solar eclipse
D) an annular lunar eclipse
E) a partial lunar eclipse if the Moon is at perigee
Answer: A
Diff: 1
Section Ref.: 0.3
40) If you are in the Moon's umbral shadow, then you are witnessing
A) nighttime.
B) a total solar eclipse.
C) a total lunar eclipse.
D) a partial solar eclipse.
E) some kind of lunar eclipse.
Answer: B
Diff: 1
Section Ref.: 0.3
41) The time for the Moon to orbit Earth, relative to the stars is
A) 23 hours, 56 minutes.
B) about 7 days.
C) 27.3 days.
D) 29.5 days.
E) 18 years, 11.3 days.
Answer: C
Diff: 1
Section Ref.: 0.3
42) The interval from new Moon to first quarter is about a(n)
A) hour.
B) day.
C) week.
D) month.
E) year.
Answer: C
Diff: 1
Section Ref.: 0.3
43) The star Thuban in Draco
A) lies as the center of the precession cycle.
B) was an excellent north pole star in 3,000 BC.
C) is brighter than Polaris.
D) lies halfway between the bowls of the Big and Little Dippers.
E) is used to locate the vernal equinox.
Answer: B
Diff: 3
Section Ref.: 0.2
44) If Scorpius is now prominent in the summer sky, in 13,000 years it will be best seen
A) at the same season; the heavens do not change.
B) in the autumn.
C) in the winter sky.
D) in the spring sky.
E) It will not be visible then at all. All of its stars will have vanished by then.
Answer: C
Diff: 3
Section Ref.: 0.2
45) If Taurus is now rising at sunset, which constellation will rise at sunset next month?
A) Scorpius
B) Aquarius
C) Gemini
D) Aries
E) Pisces
Answer: C
Diff: 3
Section Ref.: 0.2
46) The fact that the Earth has moved along its orbit in the time it took to rotate once is the reason for
A) the difference between solar and sidereal time.
B) precession.
C) seasons.
D) the position of the Celestial Equator.
E) Earth's 23.5-degree tilt.
Answer: A
Diff: 3
Section Ref.: 0.2
47) When the Moon is directly opposite the Sun in the sky, its phase is
A) new.
B) waxing or waning crescent.
C) first or third quarter.
D) waxing or waning gibbous.
E) full.
Answer: E
Diff: 2
Section Ref.: 0.2
48) You note that a particular star is directly overhead. It will be directly overhead again in
A) 1 hour.
B) 12 hours.
C) 23 hours 56 minutes.
D) 24 hours.
E) 24 hours 4 minutes.
Answer: C
Diff: 2
Section Ref.: 0.2
49) As you watch a star, you see it move 15 degrees across the sky. How long have you been watching it?
A) 1 hour
B) 3 hours
C) 15 minutes
D) 15 seconds
E) 1 minute
Answer: A
Diff: 2
Section Ref.: 0.2
50) That Polaris will not always be the pole star is due to
A) the sidereal day being shorter than the solar day.
B) precession shifting the celestial pole.
C) the Moon following the ecliptic, instead of the equator.
D) the Earth's revolution being slightly less than exactly 365.25 days.
E) the Solar winds blowing the Earth farther away from the Sun.
Answer: B
Diff: 2
Section Ref.: 0.2
51) From the horizon to the observer's zenith is an angle of
A) 30 degrees for observers at a latitude of 30 degrees North.
B) 90 degrees for everyone on the Earth.
C) 23.5 degrees for observers at the Tropics of Cancer and Capricorn.
D) 66.5 degrees for everyone on the Earth.
E) 0.0 degrees for an observer at the Earth's north pole.
Answer: B
Diff: 1
Section Ref.: 0.2
52) This diagram explains
A) the difference between solar time and sidereal time.
B) precession.
C) the solar day's relation to the Moon.
D) the sidereal day's relation to the seasons.
E) the reason for the solstices.
Answer: A
Diff: 1
Section Ref.: 0.2
53) The 26,000 year cycle that changes the poles and equinoxes is called
A) a retrograde loop.
B) the Earth's rotation.
C) precession.
D) regression.
E) revolution.
Answer: C
Diff: 1
Section Ref.: 0.2
54) The twelve constellations the solar system bodies move through are the
A) equatorial constellations.
B) signs of the zodiac.
C) nodes of the ecliptic.
D) galactic equator.
E) stages of heaven.
Answer: B
Diff: 1
Section Ref.: 0.2
55) A star with a right ascension of 1.0 hours will rise
A) 1.0 hours before the vernal equinox.
B) 13.0 hours before the vernal equinox.
C) 1.0 hours after the vernal equinox.
D) 11.0 hours after the vernal equinox.
E) at the same time as the vernal equinox.
Answer: C
Diff: 3
Section Ref.: 0.1
56) What are constellations?
A) Groups of galaxies gravitationally bound and close together in the sky.
B) Groups of stars making an apparent pattern in the celestial sphere.
C) Groups of stars gravitationally bound and appearing close together in the sky.
D) Ancient story boards, useless to modern astronomers.
E) Apparent groupings of stars and planets visible on a given evening.
Answer: B
Diff: 2
Section Ref.: 0.1
57) A star with a declination of +60.0 degrees will be
A) east of the vernal equinox.
B) west of the vernal equinox.
C) north of the celestial equator.
D) south of the celestial equator.
E) None of these answers are correct.
Answer: C
Diff: 2
Section Ref.: 0.1
58) Into how many constellations is the celestial sphere divided?
A) 12
B) 44
C) 57
D) 88
E) 110
Answer: D
Diff: 1
Section Ref.: 0.1
59) In general, what is true of the alpha star in a constellation?
A) It is the brightest star in the constellation.
B) It is the easternmost star in the constellation.
C) It is the westernmost star in the constellation.
D) It is the reddest star in the constellation.
E) It is the star that is closest to Earth.
Answer: A
Diff: 1
Section Ref.: 0.1
60) Like latitude on Earth, ________ in the sky is measured in degrees north and south of the equator.
Answer: declination
Diff: 1
Section Ref.: 0.1
61) The twelve constellations through which the Sun passes are signs of the ________.
Answer: zodiac
Diff: 1
Section Ref.: 0.2
62) The time interval of 365.242 days is defined as the ________.
Answer: tropical year
Diff: 1
Section Ref.: 0.2
63) The time for the Moon to orbit the Earth, relative to the distant stars is the ________.
Answer: sidereal month
Diff: 1
Section Ref.: 0.3
64) The apparent annual path the Sun takes through the sky is called the ________.
Answer: ecliptic
Diff: 1
Section Ref.: 0.3
65) If the Moon rises at sunset, then its phase must be ________.
Answer: full
Diff: 2
Section Ref.: 0.3
66) If the Moon is on the ecliptic, new, and at its farthest distance from Earth, we will get a(n) ________ solar eclipse.
Answer: annular
Diff: 2
Section Ref.: 0.3
67) Our seasons are a consequence of the Earth's 23.5 degree ________.
Answer: axial tilt
Diff: 1
Section Ref.: 0.3
68) Over the course of the year, the Sun's noon altitude varies by ________ degrees.
Answer: 47
Diff: 2
Section Ref.: 0.3
69) That we do not get eclipses every new and full Moon is due to the ________ degree tilt of the Moon's orbit, relative to the ecliptic.
Answer: 5.2 (or just 5)
Diff: 2
Section Ref.: 0.3
70) The apparent angular shift of any object across a distant background, when viewed from two different places, is called ________ shift.
Answer: parallax or parallactic
Diff: 1
Section Ref.: 0.4
71) Sirius has a parallax of 0.38", while Alpha Centauri's is 0.77." Alpha Centauri is about ________ as Sirius.
Answer: twice as close, or half as far
Diff: 1
Section Ref.: 0.4
72) If one star has a parallax ten times larger than another's, the first star is ________.
Answer: ten times closer than the second
Diff: 1
Section Ref.: 0.4
73) If two observatories on opposite sides of the Earth were to measure the position of a star to calculate its parallax, then the diameter of the Earth would be the ________.
Answer: baseline
Diff: 2
Section Ref.: 0.4
74) One of the requirements of the Scientific Method is that an experiment must be ________.
Answer: repeatable
Diff: 1
Section Ref.: 0.5
75) What do both latitude on Earth and declination in the sky measure?
Answer: Angular distance in degrees above or below the geographical and celestial equators.
Diff: 1
Section Ref.: 0.1
76) How is right ascension similar to longitude on Earth?
Answer: Both measure positions east or west from a fixed point; Greenwich on Earth, the vernal equinox in the sky.
Diff: 1
Section Ref.: 0.1
77) What are the minimum and maximum values for declination in the sky for both north and south?
Answer: From the equator at 0 degrees, to +90 degrees for the north celestial pole, and down to -90 degrees for the south celestial pole.
Diff: 1
Section Ref.: 0.1
78) How are right ascension in the sky and longitude on Earth different?
Answer: Right ascension is measured in units of time eastward from the vernal equinox, while longitude is measured in degrees east or west of the Greenwich meridian.
Diff: 2
Section Ref.: 0.1
79) Define the celestial sphere.
Answer: An imaginary hollow sphere, with Earth at its center, on which all the stars (and other celestial bodies) are fixed. As the sphere rotates around the Earth, the stars move across our sky.
Diff: 2
Section Ref.: 0.1
80) What are the minimum and maximum values for right ascension in the sky?
Answer: From 0 to 24 hours, going eastward from the vernal equinox.
Diff: 2
Section Ref.: 0.1
81) Which is longer, the sidereal or solar day? By how much?
Answer: The solar day is approximately four minutes longer than the sidereal day.
Diff: 1
Section Ref.: 0.2
82) At the solstice, what is the maximum angle the Sun can be above or below the equator?
Answer: +23.5 degrees in summer and -23.5 degrees in winter.
Diff: 1
Section Ref.: 0.2
83) How far above or below the ecliptic can the Sun move?
Answer: The Sun follows the ecliptic eastward across the sky, never leaving it.
Diff: 1
Section Ref.: 0.2
84) If intending to teach his students the constellations by season, why would an astronomy instructor be advised to always assign the stars in the current western sky at the beginning of each term?
Answer: As the Earth revolves around the Sun, the Sun appears to move one degree eastward per day. These stars are, therefore, soon lost in the Sun's glare.
Diff: 2
Section Ref.: 0.2
85) Which star shows the least motion in the northern sky over the course of an hour?
Answer: Polaris, the North Star, lies within a degree of the celestial pole, and does not move noticeably with the naked eye over an entire night.
Diff: 2
Section Ref.: 0.2
86) Pensacola, Florida lies at a latitude of 30 degrees north. Where is Polaris in its sky?
Answer: 30 degrees high in the north
Diff: 3
Section Ref.: 0.2
87) How far above or below the equator can the Sun appear to move? Why?
Answer: The Earth's axial tilt means the Sun's declination can reach 23.5 degrees north or south of the equator at the solstices.
Diff: 1
Section Ref.: 0.3
88) What happens on or about March 20th, and what does the name signify?
Answer: The vernal equinox, because the days and nights are approximately equal in length.
Diff: 1
Section Ref.: 0.3
89) Why are some solar eclipses total, and others annular?
Answer: The Moon's orbit is not a perfect circle. When the Moon is closer to Earth, it is big enough to cover the Sun completely; when it is too far away it appears smaller, so a ring of sunlight is still seen.
Diff: 2
Section Ref.: 0.3
90) What is the length of the sidereal month, and how is it determined?
Answer: It takes 27.3 days for the Moon to revolve around us and return to the same position against the background of stars.
Diff: 2
Section Ref.: 0.3
91) How long does the synodic month take, and how it this observed?
Answer: The phase cycle of the Moon takes 29.5 days to return to exactly the same phase.
Diff: 2
Section Ref.: 0.3
92) How far above and below the celestial equator can the Sun move?
Answer: The Sun never appears more than 23.5 degrees above or the below the celestial equator.
Diff: 2
Section Ref.: 0.3
93) The first quarter moon rises about noon today; what will its phase be, and when will it rise tomorrow?
Answer: It will be waxing gibbous, and rise about 1 PM by the next day.
Diff: 2
Section Ref.: 0.3
94) The last quarter moon rises tonight about midnight; when will it rise, and what will its phase be tomorrow night?
Answer: It will rise about an hour later, about 1 AM, and be a waning crescent by then.
Diff: 2
Section Ref.: 0.3
95) If the Moon rises exactly at sunset, what will its phase be? Why?
Answer: The phase will be full because it is rising opposite the Sun.
Diff: 2
Section Ref.: 0.3
96) Why is Polaris not always the pole star, and when does it get another chance?
Answer: Precession of the Earth's axis of rotation takes around 26,000 years.
Diff: 3
Section Ref.: 0.3
97) If Sirius transits my local meridian tonight at 6:43 PM, when will it transit tomorrow?
Answer: At 6:39 PM tomorrow night, as the Earth spins once in a sidereal day.
Diff: 3
Section Ref.: 0.3
98) Compare and contrast latitude and declination. How does each relate to your position on Earth?
Answer: Both are measured in degrees north or south of the equator, and are used to find positions on the Earth or in the sky. If you are at latitude 30 degrees north, then the stars that pass through your zenith (directly overhead) will have a corresponding declination of +30 degrees.
Diff: 2
Section Ref.: 0.1
99) Compare and contrast longitude and right ascension.
Answer: Longitude is measured in degrees both east and west of the Greenwich meridian, but right ascension is measured in units of time as the Earth rotates, and goes only eastward from the vernal equinox.
Diff: 3
Section Ref.: 0.1
100) Compare hours of right ascension to time zones on the Earth.
Answer: Like time zones, hours of right ascension are 15 degrees wide, and they run eastward across the sky from the Vernal Equinox, much like the time zones originate from the Prime Meridian.
Diff: 3
Section Ref.: 0.1
101) The Sun and stars rise in the east, and set in the west. Contrast ancient and modern explanations for this observation.
Answer: The ancients thought there was a vast celestial sphere, spinning over our heads once a day, and that the stars, Sun, Moon, and planets are all carried along for the ride. We now recognize it is the Earth itself that rotates eastward, creating this apparent westward motion of celestial bodies.
Diff: 2
Section Ref.: 0.2
102) Contrast the sidereal and solar days.
Answer: The Earth rotates once on its axis every 23 hours, 56 minutes, and thus turns to face the same distant star in that interval. But we are also revolving around the Sun at one degree eastward per day, hence the Sun appears to have moved eastward from one day to the next, and it takes a full 24 hours to align with the Sun again.
Diff: 2
Section Ref.: 0.2
103) Why can many more people witness a total lunar eclipse than a total solar eclipse?
Answer: For a total solar eclipse to be seen, the observer must be in the Moon's umbra, a shadow only about a hundred miles across, while everyone on the night side of the Earth can look up to witness the full moon moving though our shadow.
Diff: 2
Section Ref.: 0.3
104) What conditions are necessary for a total solar eclipse?
Answer: The Moon must be at new phase (directly between Earth and the Sun), it must also be both at the closer distance in its orbit and on the ecliptic (crossing a node). Only people on those parts of the Earth where the Moon's umbral shadow passes will see a total solar eclipse.
Diff: 2
Section Ref.: 0.3
105) What is the astronomical significance of 26,000 years?
Answer: The Earth's rotational axis itself rotates over this precession cycle, which also changes the location of the poles, equinoxes, and solstices in the sky.
Diff: 2
Section Ref.: 0.3
106) Describe how Eratosthenes measured the circumference of our planet.
Answer: Using the fact that the noon solstice Sun was directly overhead at Syene, on the Tropic of Cancer, yet was 7 degrees south of the zenith in Alexandria, Eratosthenes realized this was due to the curvature of the Earth, and that the 7 degrees was about 1/50th of the Earth's total circumference, so the Earth must be about fifty times larger in circumference than the 800 kilometer separation between Alexandria and Syene, or about 40,000 kilometers around.
Diff: 3
Section Ref.: 0.3
107) Which is longer, the sidereal or synodic month? Why?
Answer: The synodic month takes an extra two days, because the Earth is also revolving around the Sun, so after 27.3 days the Moon returns to the same place among the stars, but the Earth has revolved about 27 degrees ahead of where it was last month; it takes the Moon two days to catch up to us.
Diff: 3
Section Ref.: 0.3
108) We get a new and full moon every month. Why don't we get two eclipses every month?
Answer: The Moon's orbit is tilted 5.2 degrees to the Earth's orbit (the ecliptic), and the disks of the Sun and Moon are only about .5 degrees wide. Most months the new and full moon pass too far from the ecliptic for the Earth's and Moon's shadows to make eclipses occur.
Diff: 3
Section Ref.: 0.3
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