4) The Moon rises in the east and sets in the west.
5) The stars of Orion’s belt rise in the east and set in the west.
6) No one on Earth can see the constellation Orion in June.
7) Planets show retrograde motion.
8) The stars visible just after sunset are different from those visible just before sunrise.
9) If Earth’s axis had no tilt, would we still have seasons? Why or why not?
10) Do all the planets exhibit retrograde motion as seen from Earth?
11) What are the names of the two angles used to describe the location of an object in your local
sky, where, for example, an object on your north horizon would be described by the angles (0°,
0°)?
12) Why does the Milky Way appear as a band of light in the sky?
13) Consider the following statement, and explain whether or not it is sensible: Although all the
known stars appear to rise in the east and set in the west, we might someday discover a star that
will appear to rise in the west and set in the east.
14) At what altitude and in what direction in your sky does the north or south celestial pole
appear?
15) During an annular solar eclipse, is the Moon nearer or farther from Earth compared to its
average distance?
16) The ancient Greeks, in attempting to test a Sun-centered model of the solar system, would
not have expected to see parallax, because they believed that the stars were all affixed to the
celestial sphere. But they did look (unsuccessfully) for another change affecting closely
separated stars. What was that?
17) Answer each of the following questions for our local sky.
A. Where is the north celestial pole in our sky?
B. Is Polaris a circumpolar star in our sky? Explain.
C. Describe the meridian in our sky.
D. Describe the celestial equator in our sky.
18) Consider the following statement, and explain whether or not it is sensible: If you lived on
the Moon, you’d see full Earth when we see new moon.
19) Suppose you lived on the Moon near the center of the face that we see from Earth. During
the phase of full moon, what phase would you see for Earth? Would it be day or night at your
home?
20) What is the azimuth of the zenith?
21) If your computer screen had a width of 20° and you moved it ten times further away, what
would be its new angular width?
22) Given that the Moon and Sun are about the same angular width in the sky, what can you say
about their relative physical widths and distances?
23) What would you see if you were on the near side of the Moon during a lunar eclipse?
24) Why is the Moon not completely invisible (it appears as a very deep red color) to the naked
eye during a total lunar eclipse?
25) What would you see on Earth if you were on the near side of the Moon during a solar
eclipse?
26) Suppose the distance to the Moon were twice its actual value. Could we still have solar
eclipses? If so, what type(s)?
27) Consider the following statement, and explain whether or not it is sensible: Last night I saw
Mars move eastward through the sky in its apparent retrograde motion.
2.5 Mastering Astronomy Reading Quiz
1) About how many stars are visible to the naked eye on a clear, dark night away from city
lights?
A) a few dozen
B) approximately two thousand
C) several million
D) a few hundred billion
2) What do astronomers mean by a constellation?
A) A constellation is a region in the sky as seen from Earth.
B) A constellation is a group of stars related through an ancient story.
C) A constellation is any random grouping of stars in the sky.
D) A constellation is a group of stars that are all located in about the same place in space.
3) What is the ecliptic?
A) the path the Sun appears to trace around the celestial sphere each year
B) the Sun’s daily path from east to west in our sky
C) the path traced by the Moon’s shadow on Earth during a solar eclipse
D) a half-circle extending from your horizon due north, through your zenith, to your horizon due
south
4) What is the celestial sphere?
A) The celestial sphere is a representation of how the entire sky looks as seen from Earth.
B) The celestial sphere is a model that shows the true locations in space of the Sun and a few
thousand of the nearest stars.
C) The celestial sphere is a model of how the stars are arranged in the sky relative to our Sun,
which is in the middle of the sphere.
D) It represents a belief in an Earth-centered universe, and hence is no longer considered to have
any use.
5) As Earth goes around the Sun each year, Earth’s rotation axis in the North points
A) tipped toward the Sun, 23-1/2 degrees.
B) in a direction that traces a cone of radius 23-1/2 degrees, crossing through Polaris and Vega.
C) tipped toward the galactic center, 23-1/2 degrees.
D) in the direction of the celestial pole, near Polaris, throughout the year.
6) Which of the following statements does not use the term angular size or angular distance
correctly?
A) The angular distance between those two houses in the distance is 30 degrees.
B) The angular distance between those two bright stars in the sky is about 2 meters.
C) The angular size of the Sun is about the same as that of the Moon.
D) You can use your outstretched hand against the sky to estimate angular sizes and angular
distances.
7) Which of the following correctly describes the meridian in your local sky?
A) a half-circle extending from your horizon due east, through your zenith, to your horizon due
west
B) a half-circle extending from your horizon due east, through the north celestial pole, to your
horizon due west
C) a half-circle extending from your horizon due north, through your zenith, to your horizon due
south
D) the point directly over your head
8) The point directly over your head is called ________.
A) the meridian
B) the zenith
C) the north celestial pole
D) the North Star
9) Stars in the local sky that never cross below the horizon during the year are called ________.
A) bright
B) seasonal
C) circumpolar
D) celestial
10) We describe a location on Earth’s surface by stating its ________.
A) altitude and direction (or azimuth)
B) meridian and longitude
C) latitude and direction
D) latitude and longitude
11) If you are located in the Northern Hemisphere, how can you learn how far you are from the
North Pole?
A) The altitude of the north celestial pole equals your latitude.
B) The altitude of the celestial equator equals your latitude.
C) The altitude of the north celestial pole equals your longitude.
D) The longitude of the north celestial pole is circumpolar, and therefore crosses your zenith at
the meridian.
12) Which of the following best describes why we have seasons on Earth?
A) The tilt of Earth’s axis causes different portions of the Earth to receive more direct sunlight
and more hours of sunlight at different times of year.
B) Earth’s elliptical orbit means we are closer to the Sun and therefore receive more intense
sunlight at some times of year than at others.
C) The tilt of Earth’s axis causes the northern hemisphere to be closer to the Sun than the
southern hemisphere in summer, and vice versa in winter.
D) The varying speed of Earth in its orbit around the Sun gives us summer when we are moving
fastest and winter when we are moving slowest.
13) Each choice below describes how a few astronomical phenomena are related to time periods.
Which list is entirely correct? (Careful: some lists are partially correct.)
A) Earth’s rotation defines a day.
The cycle of the Moon’s phases takes about a month.
Earth’s orbit defines a year.
Earth’s cycle of axis precession takes 26,000 years.
B) Earth’s rotation defines a day.
The cycle of the Moon’s phases takes about a week.
Earth’s orbit defines a year.
Earth’s cycle of axis precession defines a month.
C) Earth’s rotation defines a day.
The Sun’s rotation defines a week.
The Moon’s rotation defines a month.
Earth’s orbit defines a year.
D) Earth’s rotation defines a day.
The saros cycle of eclipses defines a month.
Earth’s orbit defines a year.
Earth’s cycle of axis precession takes 26,000 years.
14) If we have a new moon today, when will we have the next full moon?
A) in about two weeks
B) in about 1 week
C) in about 1 month
D) in about 6 months
15) The Moon’s angular width is
A) 1/2 degree.
B) 1/2 arcminute.
C) 1/2 arcsecond.
D) it changes, growing larger at the horizon.
16) Lunar eclipses can occur only during a ________.
A) new moon
B) first quarter moon
C) full moon
D) third quarter moon
17) What is the saros cycle?
A) the 26,000-year cycle of the Earth’s precession
B) the roughly 18-year cycle over which the pattern of eclipses repeats
C) the roughly one-month cycle of lunar phases in the sky
D) the annual cycle of the seasons
18) During the time that a planet is in its period of apparent retrograde motion, ________.
A) the planet moves backwards (clockwise as viewed from above Earth’s north pole) in its orbit
of the Sun
B) the planet appears to rise in the west and set in the east, rather than the usual rising in the east
and setting in the west
C) over many days or weeks, the planet moves westward relative to the stars, rather than the
usual eastward relative to the stars
D) the planet is getting closer to the Sun in its orbit
19) What is stellar parallax?
A) It is the daily rise and set of the stars.
B) It describes the fact that stars are actually moving relative to one another, even though to our
eyes the stars appear fixed in the constellations.
C) It is the slight back-and-forth shifting of star positions that occurs as we view the stars from
different positions in Earth’s orbit of the Sun.
D) It is the change in the set of constellations that we see at different times of year in the evening
sky.
20) The ecliptic crosses the celestial equator on the celestial sphere at points called
A) the equinoxes.
B) the solstices.
C) the nodes.
D) aphelion and perihelion.
2.6 Mastering Astronomy Concept Quiz
1) Which of the following statements about the celestial sphere is not true?
A) The Earth is placed at the center of the celestial sphere.
B) When we look in the sky, the stars all appear to be located on the celestial sphere.
C) The “celestial sphere” is another name for our universe.
D) The celestial sphere does not exist physically.
2) If the Earth’s rotation axis were tilted by 45 degrees instead of 23.5 degrees, what are some of
the implications, and why?
A) The seasons would be more extreme, because the Sun’s rays would be more direct in summer,
and less direct in winter.
B) The seasons would be less extreme, because the Sun’s rays would be less direct in summer,
and more direct in winter.
C) The seasons would be less extreme, because the surface of the Earth would be farther from
the Sun in the summer, and closer to the Sun in the winter.
D) The seasons would be more extreme, because the surface of the Earth would be closer to the
Sun in the summer, and farther from the Sun in the winter.
3) Tonight, your telescope shows you RXJ1800, a galaxy, very near in the sky to the bright star
Vega. What can you conclude from this observation?
A) RXJ1800 and Vega will drift apart from each other on the sky, over a matter of nights.
B) Vega and RXJ1800 must be very close to each other, less than a few light-years.
C) Vega orbits the center of mass of RXJ1800.
D) RXJ1800 and Vega will set in the west, at very similar times.
4) When traveling north from the United States into Canada, you’ll see the North Star (Polaris)
getting ________.
A) brighter
B) dimmer
C) higher in the sky
D) lower in the sky
5) Suppose you use the Southern Cross to determine that the south celestial pole appears 40
degrees above your horizon. Then you must be located at ________.
A) latitude 40 degrees north
B) latitude 50 degrees south
C) latitude 40 degrees south
D) longitude 40 degrees
6) Suppose you are facing north and you see the Big Dipper close to your northern horizon, with
Polaris (and the Little Dipper) above it. Where will you see the Big Dipper in six hours?
A) to the right of Polaris; that is, 90 degrees counterclockwise from its current position
B) to the left of Polaris; that is, 90 degrees clockwise from its current position
C) directly above Polaris
D) still in the same place, below Polaris
7) In any particular place on Earth, certain constellations are visible in the evening only at certain
times of the year because ________.
A) our evening view of space depends on where Earth is located in its orbit around the Sun
B) during some times of year, some constellations drop below the southern horizon
C) some constellations are circumpolar
D) on any particular night, we can only see stars that are directly opposite (180 degrees away
from) the Sun in the sky
8) The Greeks rejected the notion that the Earth orbits the Sun. Why?
A) They could not measure how big the Earth was.
B) They could not measure a change in stars’ positions on the sky.
C) They were not as smart as we are.
D) They believed that the Sun is a God.
9) Your friend tells you that last night, they saw Mars high in the sky at midnight. You conclude
that
A) Mars must be in retrograde.
B) your friend must be mistaken: Mars can never be seen at midnight.
C) Mars must be at its farthest distance from the Earth.
D) Mars must be at its closest distance from the Sun.
10) If our year were twice as long (that is, if Earth took twice as many days to complete each
orbit around the Sun), but Earth’s rotation period and axis tilt were unchanged, then ________.
A) stars would take twice as long to rise and set
B) the cycle of precession would take 13,000 years instead of 26,000 years
C) the four seasons would each be twice as long as they are now
D) the Earth would not have seasons
11) How does Earth’s varying distance from the Sun affect our seasons?
A) It doesn’t. Earth’s orbital distance plays no significant role in the seasons.
B) It makes summer warmer in the Northern Hemisphere than in the Southern Hemisphere.
C) It is responsible for the fact that the seasons are opposite in the Northern and Southern
hemispheres.
D) It causes the seasons to be more extreme than they would be if the Earth’s distance from the
Sun were always the same.
12) Suppose you live in the United States and you see a crescent moon in your evening sky
tonight. What will a friend in South America see tonight?
A) Your friend will see a gibbous moon.
B) Your friend will also see a crescent moon.
C) Your friend will see a first quarter moon.
D) Your friend won’t see the Moon tonight, because it is up only in the morning.
13) During a lunar eclipse the Moon’s phase must be
A) full.
B) new.
C) 1st quarter.
D) 3rd quarter.
14) If the Moon is 3rd quarter phase, what shape does it have in the sky?
A) a quarter circle
B) a full circle
C) a half circle
D) nothing (It is impossible to view a 3rd quarter moon.)
15) Earth’s distance from the Sun varies during the year
A) not at all.
B) by 3%.
C) by 10%.
D) by 30%.
16) Which of these (hypothetical) modifications would cause lunar eclipses to happen once per
month?
A) Make the Moon orbit the Earth twice as fast.
B) Relocate the Moon to twice its current distance from the Earth.
C) Change the Moon’s orbital plane so it tilts the opposite way.
D) Change the orbital plane of the Moon so it lies in the same plane as Earth’s orbit around the
Sun.
17) The Moon is nearly tidally locked to the Earth, which means the Moon’s rotation period is
almost the same as its orbital period. If you were camped at the equator of the Moon, you would
experience (approximately)
A) 14 hours of darkness followed by 14 hours of sunshine.
B) sunshine all the time, except when the Earth blocks the Sun.
C) (14 × 24) hours of darkness followed by (14 × 24) hours of sunshine.
D) sunshine (day) all the time.
18) During the period each year when we see Mars undergoing apparent retrograde motion in our
sky, what is really going on in space?
A) Mars is moving around the Sun in the opposite direction from which Earth is moving around
the Sun.
B) Earth and Mars are getting closer together.
C) Earth is catching up with and passing by Mars in their respective orbits.
D) Earth and Mars are on opposite sides of the Sun.
19) Which of the following conditions must exist for a solar eclipse to occur?
A) The only condition is that the phase of the Moon must be new.
B) The only condition is that the phase of the Moon must be full.
C) Moon phase is new, and the Moon is passing through the Earth’s orbital plane.
D) Moon phase is full, and the Moon is passing through the Earth’s orbital plane.
20) RXJ1800, a galaxy, lies very near in the sky to the bright star Vega. What is the best
explanation for them appearing close together?
A) Their random motions have caused RXJ1800 and Vega to drift to within a few light-years of
each other.
B) They coincidentally lie along the same line of sight.
C) Vega orbits the center of mass of RXJ1800.
D) Vega must have recently formed in RXJ1800 and been ejected.
21) You are standing on Earth’s equator. In which direction is Polaris, the North star?
A) The answer depends on what time of day (or night) it is.
B) The answer depends on whether it is winter or summer.
C) It is on the northern horizon.
D) It is directly overhead.
22) You observe a full moon rising at sunset. What will you see 6 hours later?
A) a full moon on or near your meridian
B) a waning gibbous moon
C) a first quarter moon
D) a third quarter moon
23) Why is it summer in the Northern Hemisphere when it is winter in the Southern Hemisphere?
A) The Northern Hemisphere is “on top” of Earth and therefore receives more sunlight.
B) The Northern Hemisphere is tilted away from the Sun and receives more indirect sunlight.
C) The Northern Hemisphere is tilted toward the Sun and receives more direct sunlight.
D) It isn’t: both hemispheres have the same seasons at the same time.
E) The Northern Hemisphere is closer to the Sun than the Southern Hemisphere.
24) Today the Sun is in the middle of the constellation Virgo. Therefore, tomorrow the Sun will
be in the constellation
A) Libra.
B) Virgo.
C) Leo.
D) Sagittarius.
25) If Earth’s rotation axis was tilted by 45 degrees instead of 23.5 degrees, what are some of the
implications, and why?
A) The seasons would be more extreme, because the Sun’s rays would be more direct in summer,
and less direct in winter.
B) The seasons would be more extreme, because the surface of the Earth would be closer to the
Sun in the summer, and farther from the Sun in the winter.
C) The seasons would be less extreme, because the Sun’s rays would be less direct in summer,
and more direct in winter.
D) The seasons would be less extreme, because the surface of the Earth would be farther from
the Sun in the summer, and closer to the Sun in the winter.
26) The phenomenon where Earth’s rotation axis slowly makes a circle in the celestial sphere
over 26,000 years is called
A) spin-coupling.
B) osculation.
C) contortion.
D) precession.
27) If Earth rotated once every 48 hours, and everything else was the same, which of the
following statements would not be true?
A) There would still be summer and winter in the temperature zones.
B) The length of the year would be longer.
C) The daytime temperatures would be higher on average.
D) High tide would happen less frequently.
E) The length of a day would be longer.
28) Polaris is 10 degrees above your horizon. Where are you?
A) Latitude 10 degrees north
B) Latitude 10 degrees south
C) Latitude 80 degrees north
D) Latitude 80 degrees south
29) We see two stars separated by one degree on the celestial sphere. What can we infer about
these stars?
A) They are very close together in space.
B) They have similar luminosities.
C) They rise and set at about the same time.
D) They were born about the same time.
30) The parallax angle of two stars is reported in a star catalog. Which star is farther?
A) The one with the larger parallax angle
B) You can’t tell, since parallax angle has nothing to do with distance.
C) The one with the smaller parallax angle
31) If Earth’s rotation slowed down so that it completed exactly one rotation about its axis in 100
hours, what would be the typical time interval between sunrise and sunset?
A) 24 hours
B) 25 hours
C) 50 hours
D) 100 hours
32) When the Moon’s phase is a first quarter moon, it rises
A) just before sunset.
B) just after sunset.
C) around noon.
D) close to sunrise.