Deck 3: Eclipses and the Motion of the Moon

Question 1

Which way will the "horns," or sharp ends of the crescent, of the Moon point in the sky when the Moon is above the western horizon at sunset, at a phase 3 days after new moon? (Hint: Think about what causes the crescent phase of the Moon; Figure 3-2 of Universe, 11th ed., may help.)
​
​

A)The horn points toward the Sun, westward.
B)The Moon is not crescent shaped at this phase.
C)The horn points at a right angle to direction of the Sun, northward.
D)The horn points away from the Sun, eastward.

Answer 1

D

Question 2

When will the first quarter moon rise, approximately? (You may want to examine Figure 3-2 of Universe, 11th ed., and think about where you would need to stand on Earth to see the first quarter moon rising.)
​

A) 6 A.M.
B) noon
C) 3 A.M.
D) 6 P.M.

Answer 2

B

Question 3

If on a particular day the Sun is at one of the solstices and the Moon is at one of the equinoxes, then the lunar phase on that day is:

A)not predictable from this information alone.
B)full.
C)new.
D)either first or last quarter.

Answer 3

D

Question 4

The waxing gibbous phase of the Moon occurs when the Moon passes:

A)from third quarter to new moon.
B)between the two positions when the Moon and the Sun are at right angles to each other during which new moon occurs.
C)from new moon to first quarter.
D)from first quarter to full moon.

Question 5

The waning gibbous phase of the Moon occurs when the Moon passes:

A)from third quarter to new moon.
B)between the two positions when the Moon and the Sun are at right angles to each other during which a new moon occurs.
C)from full moon to third quarter.
D)from first quarter to full moon.

Question 6

If the Moon is located at the vernal equinox on September 20, what is the phase of the Moon?

A)new
B)third quarter
C)first quarter
D)full

Question 7

When does the third quarter moon rise? (You may want to examine Figure 3-2 of Universe, 11th ed., and think about where you would need to stand on Earth to see the third quarter moon rising.)
​

A) about 6 A.M.
B) close to noon
C) about 6 P.M.
D) close to midnight

Question 8

Is the Moon ever visible during the daytime (on a clear day)?

A)It is only during solar eclipses, when the sky is dark.
B)No, the Moon is never visible during the daytime.
C)Yes, but only if the Sun is very close to the horizon (just after sunrise or just before sunset).
D)Yes, whenever the Moon is above the horizon and it is not close to new moon.

Question 9

The Moon would NOT go through phases if:

A)it were tilted on its axis, like Earth.
B)it did not rotate.
C)it took 1 year to go around Earth.
D)(in addition to the Moon going around Earth) the Sun went around Earth instead of Earth around the Sun.

Question 10

Which one of the following affects the rate at which the Moon goes through its phases?

A)the rotation period of the Moon about its axis
B)the rotation period of Earth about its axis
C)the period of Earth's motion around the Sun
D)the period of the Moon's motion around Earth

Question 11

If an observer on Earth sees the Moon to be full, then at the same time an observer on the Moon would see Earth to be at what phase?

A)full
B)new
C)third quarter
D)Earth does not appear to go through phases when observed from the Moon.

Question 12

If an observer on Earth sees the Moon to be at first quarter, then at the same time, an observer on the Moon would observe Earth to be at what phase?

A)first quarter
B)third quarter
C)full
D)Earth does not appear to go through phases when observed from the Moon.

Question 13

If the Moon is now in its waxing crescent phase, 2 weeks from now it will be:

A)waxing gibbous.
B)full.
C)waning gibbous.
D)waning crescent.

Question 14

If the Moon is now in its waxing crescent phase, 1 week ago it was:

A)new.
B)waning crescent.
C)waxing gibbous.
D)full.

Question 15

If the Moon is now in its waxing crescent phase, 1 week from now it will be:

A)new.
B)waning crescent.
C)waxing gibbous.
D)full.

Question 16

Suppose the Moon orbited Earth with the same period it has now but in the opposite direction. Which one of the following would NOT change?

A)the length of a synodic month
B)the length of a sidereal month
C)the frequency of solar eclipses
D)the frequency of lunar eclipses

Question 17

Suppose the Moon rotated on its axis with the same period it has now but in the opposite direction. Which of the following would change?

A)the length of a synodic month
B)the length of a sidereal month
C)the frequency of lunar eclipses
D)None of these would change.

Question 18

How does the Moon rotate to keep one face pointed toward Earth at all times, as can be seen in Figure 3-4 of Universe, 11th ed.?
​
​

A)It rotates once per month.
B)It rotates once per year.
C)It rotates once per day.
D)It does not rotate at all.

Question 19

To observers on the near side of the Moon, Earth:

A)rises in the east and sets in the west.
B)rises in the west and sets in the east.
C)appears overhead at all times.
D)is not visible at any time.

Question 20

If you were standing on the Moon in darkness on the opposite side from Earth at a particular time, which of the following conditions would be true?

A)You would never see the Sun from that position.
B)You would see Earth in about 7 days.
C)It would take about 1/4 year (3 months) before you would see Earth from that position.
D)You would never see Earth from that position.

Question 21

Which of the following statements about the Moon's position and motion is NOT correct?

A)The Moon does not rotate at all, since it keeps one face toward Earth at all times.
B)The Moon's rotation period is equal to its orbital period.
C)The time from full moon to full moon is longer than the Moon's orbital period.
D)The time from full moon to full moon is longer than the Moon's rotation period on its axis.

Question 22

As seen by a distant observer who is fixed with respect to the stars, approximately how long does it take for the Moon to rotate once around its own axis?

A)1 month
B)Forever, since one side of the Moon always faces toward Earth, the Moon does not rotate.
C)1 day
D)1 year

Question 23

The approximate rotation period of the Moon is:

A)1 day.
B)1 week.
C)1 month.
D)infinite, since the Moon does not rotate, but keeps one face toward Earth at all times.

Question 24

During a month we see only approximately half of the moon's surface. Which one of the following changes would allow us to see all of the Moon's surface during 1 month?

A)reversing the direction of the Moon's rotation about its axis
B)changing the period of Earth's motion around the Sun
C)reversing the direction of Earth's motion around the Sun
D)reversing the direction of Earth's rotation about its axis

Question 25

The Moon is now in its waxing crescent phase. If you could view the far side of the Moon it would be:

A)full.
B)waxing crescent.
C)waning gibbous.
D)dark, as always.

Question 26

You are standing at the equator of the Moon and a particular star is overhead at that time. How long will it be before that star is approximately overhead again?

A)The star will always remain overhead since the Moon does not rotate on its axis.
B)29 1/2 days
C)365 1/4 days
D)27 1/3 days

Question 27

If astronauts landed on the Moon near the center of the visible surface at full moon, how many Earth days would pass before the astronauts would experience darkness on the Moon?

A)1 week
B)2 weeks
C)1 month
D)They would never experience darkness.

Question 28

If Earth orbited the Sun in half the time it does now, how would the length of time between full moons change?

A)It would not change at all.
B)It would double.
C)It would be halved.
D)It would increase but not double.

Question 29

Approximately how long will it take for the dark-light dividing line on the Moon, the terminator, to move through 90° of lunar longitude?

A)91 days or 1/4 year
B)6 hours or 1/4 day
C)The dark-light line never moves around the Moon since the Moon does not rotate on its axis.
D)7 days

Question 30

One day from sunrise to sunrise for a space explorer at her lunar base will be how many Earth days long? (A diagram might help.)

A)365 1/4 days
B)29 1/2 days
C)1 day
D)27 1/3 days

Question 31

The fact that the Earth-Moon system orbits the Sun (covering 30° per month) in a clockwise direction viewed from the celestial north pole while the Moon orbits Earth, also in a clockwise direction, means that the time between successive full moons, the synodic month, compared to one lunar orbital (sidereal) period is:

A)about twice as long.
B)about 2 days longer.
C)about 2 days shorter.
D)about 2 weeks longer.

Question 32

The Moon rises later each day because each day it has moved farther along its orbit around Earth (except for observers at polar latitudes, for whom the Moon can remain above or below the horizon for 24 hours each day). On average, how much later does it rise each day (you might attempt to verify this by observation)? (Hint: What fraction of a month does a day take up?)

A)4 minutes
B)20 minutes
C)2 hours
D)1 hour

Question 33

How fast does the Moon move across our sky against the background of stars? (Hint: Through what angle does the Moon move around the sky in 1 month?)

A)15° per hour
B)1° per day
C)its own diameter per day
D)13° per day

Question 34

In 1 hour, the motion of the Moon across our sky as seen against the background of stars is: (Hint: Through what angle around the sky does the Moon move in 1 month?)

A)its own diameter or 1/2°
B)4°
C)1/10°
D)13°

Question 35

Earth and the Moon both move eastward in their orbits. Suppose the Moon moved westward instead, at the same rate as its actual eastward movement. What consequence would this have?

A)1 synodic month would be the same length it is now.
B)1 sidereal month would be the same length it is now.
C)Both synodic and sidereal months would be shorter than they are now.
D)Both synodic and sidereal months would be longer than they are now.

Question 36

The Moon moves eastward in its orbit. It always keeps the same face toward Earth. This means that it:

A)does not rotate.
B)rotates toward the east.
C)rotates toward the west.
D)rotates toward the east half of the time and toward the west the other half of the time.

Question 37

Earth rotates eastward on its axis. The Moon moves to the east in its orbit around Earth. The Moon also rises about 1 hour later each night. Suppose the Moon moved westward instead. What consequence would this have?

A)The Moon would still rise about 1 hour later each night.
B)The Moon would rise about 1 hour earlier each night.
C)The Moon would rise earlier each night, but only be about half an hour.
D)The Moon would rise later each night, but only be about half an hour.

Question 38

The gravitational pull of the Sun on the Moon causes each one of the changes listed below EXCEPT ONE. Which one is the EXCEPTION?

A)The length of a sidereal month varies slightly from one orbit to the next.
B)The length of a synodic month varies slightly from one orbit to the next.
C)The Moon's orbit changes slightly from one month to the next.
D)The appearance of the Moon seen from Earth varies significantly from one month to the next.

Question 39

During a total lunar eclipse (as viewed from Earth) you are standing on the Moon looking back at Earth. What do you see?

A)The Moon's shadow is visible as a small spot on Earth's surface.
B)The Moon's shadow covers the entire Earth.
C)Earth just covers the disk of the Sun with the solar atmosphere showing around the edges.
D)Earth appears as a black disk with only a faint glow around the edges.

Question 40

In a period of 1 month, the Moon moves across the sky:

A)parallel to the horizon.
B)precisely along the ecliptic plane.
C)precisely along the celestial equator.
D)along a plane that is neither the ecliptic plane nor the celestial equator, nor is it parallel to the horizon.

Question 41

If the Moon in its orbit around Earth moves between Earth and the Sun and then 2 weeks later it moves to the other side of Earth as seen from the Sun, why then do we not see both a solar and a lunar eclipse every month?

A)The Moon's orbital plane is at right angles to the ecliptic.
B)Earth's orbital plane is slightly inclined to the ecliptic.
C)The Moon's orbital plane is slightly inclined to the ecliptic.
D)The Moon's orbital plane is inclined slightly to the celestial equator.

Question 42

You travel to an exotic place to observe a total solar eclipse in December and someone on this trip tells you that the next eclipse to occur on Earth will be a lunar eclipse in March. Is this likely to be true?

A)It could be true, since such an eclipse can occur when the Sun's position with respect to the celestial equator is changing rapidly.
B)Yes, but only once about every 1000 years.
C)No, it is not likely to be true.
D)Yes, it is likely to be true.

Question 43

What is the declination of the Moon?

A)0°
B)+5°
C)-5°
D)a number that changes significantly over 1 month

Question 44

What is the right ascension of the Moon?

A)0 hours
B)20 minutes
C)23 hours 40 minutes
D)a number that changes significantly over 1 month

Question 45

When in total lunar eclipse, the Moon shows a reddish color because:

A)light from the northern and southern lights (the aurora) on Earth, which is predominantly red, illuminates the Moon.
B)this is the color of the residual thermal glow from a still-warm Moon, after the abrupt removal of the heat of the Sun.
C)the Moon is illuminated only by the residual glow from the dark side of Earth, which is predominantly red.
D)the red part of the solar spectrum, predominantly, is deflected onto the Moon by Earth's atmosphere.

Question 46

One eclipse year is the time needed for:

A)three saros intervals.
B)the line of nodes of the Moon's orbit to go from alignment with respect to the Sun-Earth line to the next identical alignment.
C)365 successive eclipses.
D)two consecutive identical alignments of the Sun, the Moon, and the line of nodes.

Question 47

The saros is the period of time between:

A)successive solar eclipses in a series of similar eclipses at about the same latitude on Earth.
B)two successive total lunar eclipses, seen from the same point of Earth.
C)two successive passages of the Sun through the vernal equinox.
D)two successive eclipse seasons, about 6 months.

Question 48

Total solar eclipses seen at approximately the same latitude occur in a sequence with a time interval, the saros, of 223 lunar sidereal months. How many eclipse years is this?

A)19
B)16.7
C)18
D)17.6

Question 49

The time interval between one total solar eclipse and the next total solar eclipse, visible from the same location on Earth, must be all of the following EXCEPT ONE. Which is the EXCEPTION?

A)a whole number of lunar months
B)a whole number of sidereal months
C)a whole number of eclipse years
D)a whole number of saros intervals

Question 50

How does the duration of a total solar eclipse compare with the duration of a total lunar eclipse?

A)The solar eclipse is always longer.
B)The lunar eclipse is always longer.
C)They are the same length.
D)Depending on where the Moon and Earth are in their orbits, either eclipse might be longer.

Question 51

Which significant observation led the Greeks to accept the idea that Earth was a sphere?

A)The shape of the darkening across the Sun's disk during a solar eclipse always appeared circular.
B)The shape of Earth's shadow on the Moon during a lunar eclipse was always circular.
C)The Sun disappears below one horizon each day and reappears above the opposite horizon.
D)The shape of the eclipse shadow on Earth during a solar eclipse was always circular.

Question 52

The Greek astronomer who first measured the radius of Earth reasonably accurately was:

A)Archimedes.
B)Eratosthenes.
C)Aristotle.
D)Ptolemy.

Question 53

Eratosthenes, an ancient Greek astronomer, is famous for:

A)measuring the diameter of Earth by comparing the direction to the Sun at noon at two different points on Earth.
B)measuring the diameter of Earth by timing how long it took the Moon to traverse Earth's shadow during a lunar eclipse.
C)measuring the relative distances to the Sun and the Moon by timing the exact moments when the Moon was at first and third quarter.
D)measuring the distance to each of the known planets by timing how long it took the planet to orbit the Sun.

Question 54

Eratosthenes measured the radius of Earth by:

A)timing the disappearance of the Sun at sunset for two different positions on Earth on the same day of the year.
B)estimating the size of the shadow of Earth on the Moon during a lunar eclipse.
C)measuring the angular position of the pole star from several positions on Earth.
D)noting the different angles of the Sun at midday on the same day of the year at different positions on Earth.

Question 55

Eratosthenes, an astronomer in ancient Greece, measured the radius of Earth by making observations of:

A)the Sun's direction at midday at two positions on Earth, on the same day of the year.
B)the tidal ebb and flow of ocean waters.
C)the deviation of magnetic north, as seen from a compass, from true north.
D)relative times of arrival of the Sun due south of an observer at two positions on Earth.

Question 56

The ancient Greek astronomer Aristarchus is famous for devising a method for measuring the:

A)length of an eclipse cycle.
B)diameter of Earth.
C)relative distances of the Sun and the Moon.
D)precise distance between Alexandria and Syene in ancient Egypt.

Question 57

In about 280 B.C., Aristarchus devised a method of estimating the relative distance of the Sun and the Moon from Earth by:

A)measuring the angle between the Sun and Moon when the Moon is at first or third quarter.
B)calculating their orbital radii from their orbital periods around Earth, using Kepler's law.
C)noting the size of Earth's shadow on the Moon during a lunar eclipse.
D)estimating the positions of the Moon and Sun in the sky from different positions on Earth as they passed through the due south direction on the same day.

Question 58

Which of the following investigations did the Ancient Greeks NOT carry out?

A)determination that Earth's orbit around the Sun is an ellipse
B)determination that Earth is approximately spherical
C)measurement of the relative distances of the Moon and the Sun from Earth
D)measurement of Earth's radius

Question 59

How did the ancient Greek astronomer Aristarchus of Samos determine that the Moon's diameter was about 1/3 that of Earth?

A)by measuring the time it takes the Moon to cross the face of the Sun during a solar eclipse
B)by measuring the relative durations of lunar and solar eclipses
C)by measuring the time it takes the Moon to pass in front of a background star
D)by measuring the time it takes the Moon to move through Earth's shadow during a lunar eclipse

Question 60

What is the diameter of the Moon compared to that of Earth, as measured by the ancient Greek astronomer Aristarchus of Samos?

A)1/3 the diameter of Earth
B)1/20 the diameter of Earth
C)20 times the diameter of Earth
D)3 times the diameter of Earth

Question 61

One of the most significant achievements of the ancient Greeks was the:

A)logical thinking and mathematical reasoning that they applied to natural phenomena.
B)precision with which they measured the distances of the Sun and Moon from Earth.
C)acceptance that the Sun and not Earth was at the center of the universe.
D)strengthening of the belief in gods who controlled the behavior of the natural world.

Question 62

The attempt by Aristarchus to measure the relative distances to the Sun and to the Moon from Earth produced a result now known to be incorrect. The source of this error was that:

A)Aristarchus did not know the distance to the Moon to any great precision.
B)Aristarchus' hypothesis was fundamentally incorrect.
C)Aristarchus was unable to measure accurately the angle between the Moon and Sun at first or third quarter.
D)the Moon-Sun-Earth angle is not really a right angle at first and third quarters.

Question 63

During a total solar eclipse the Moon just covers the Sun as viewed from Earth. If you know both the diameter and distance of the Moon, what else can you determine from this information?

A)the diameter of the Sun but not its distance
B)the distance to the Sun but not its diameter
C)both the diameter and distance to the Sun
D)only the ratio of the Sun's diameter to its distance

Question 64

At the ancient Egyptian city of Syene, the Sun was directly overhead only at summer solstice. Thus, Syene must have been very close to:

A)the equator.
B)the Tropic of Cancer.
C)the Tropic of Capricorn.
D)the prime meridian.

Question 65

Aristarchus measured the Sun-Earth-Moon angle at quarter moon to be 87° and calculated that the Sun is 20 times as far away as the Moon. Actually, the Sun is almost 400 times as far away as the Moon. Thus the actual Sun-Earth-Moon angle at quarter moon must be:

A)less than 45°.
B)45°.
C)86.5°.
D)89.5°.

Question 66

In order to obtain the shadow lengths he did, Eratosthenes had to make his measurements on the:

A)vernal equinox.
B)summer solstice.
C)autumnal equinox.
D)winter solstice.

Question 67

Suppose Eratosthenes had measured the length of a shadow at Syene and then compared it with the shadow measured not at Alexandria, but at a location half way between Syene and Alexandria-both measurements being made at the summer solstice. What would he have found?

A)The difference in the lengths of these shadows would have been greater than that found by comparing Syene and Alexandria, suggesting a larger value for the circumference of Earth than what he actually found.
B)The difference in the lengths of these shadows would have been larger than that found by comparing Syene and Alexandria, suggesting a smaller value for the circumference of Earth than what he actually found.
C)The difference in the lengths of these shadows would have been smaller than that found by comparing Syene and Alexandria.
D)The difference in the lengths of these shadows would have been the same as that found by comparing Syene with Alexandria.