Felicia Barrow: Practice Quiz #11 (Topic #5)

Summary of results:

Your score on this quiz is 80% (incorrect choices are highlighted in red).

#1. If you observe the Moon in the figure below, what phase will it have?

#2. If the Moon is located as shown in the figure below, where would it be located in the sky at 3am?

#3. If the waning gibbous Moon is rising on the eastern horizon, what time of the day or night is it?

#4. If the Moon is currently in the waning gibbous phase, what phase will it have in seventeen to eighteen days from now?

#5. If the waning crescent Moon rose nine hours ago, what time of the day or night is it?

Elapsed Time: 27 minutes

#1. If you observe the Moon in the figure below, what phase will it have?

full new
waning gibbous waxing crescent
third quarter first quarter
waning crescent waxing gibbous


The Moon is located on the same side of the Earth as the Sun. It does not appear illuminated from Earth, and thus is in the new phase.

      

#2. If the Moon is located as shown in the figure below, where would it be located in the sky at 3am?

rising on the eastern horizon
well above the eastern horizon, but not yet overhead
almost directly overhead (as high in the sky as it will get)
well above the western horizon, but no longer overhead
setting on the western horizon
hidden below the horizon


Wherever the Moon lies in the sky, it will always be visible from the half of the Earth pointing toward it and hidden from sight from the half of the Earth pointing away from it. Recall that our figure shows us looking down on the Earth and Moon from above the north pole; the Earth rotates once counterclockwise in place each day. We can thus use the fact that noon is defined as the time at which the Sun is highest in the sky, and midnight as the time when the Sun is most hidden, to place a 24 hour clock dial on top of the Earth. We label the times at which the Moon will be visible from Earth in green, from the time at which it starts to rise above the horizon to the time at which it starts to set below the horizon. We can thus see that at 3am the Moon will lie well above the horizon (and by 6am it will be setting).

      

#3. If the waning gibbous Moon is rising on the eastern horizon, what time of the day or night is it?

midnight (12am) noon (12pm)
early morning (3am) afternoon (3pm)
dawn (6am) dusk (6pm)
morning (9am) evening (9pm)


The Moon is in the waning gibbous phase when it appears mostly illuminated from Earth, in the days after a full Moon (with each passing night, a little bit less of the Moon will be illuminated). It will be located on the opposite side of the Earth from the Sun, coming out from behind the Earth and moving around to the side. When we are underneath this point we are on the side of the Earth hidden (shadowed) from the Sun, so it must be nighttime. The waning gibbous Moon will lie directly overhead when we have rotated an eighth of the way around past midnight. This occurs three hours later, at 3am. The Moon will rise six hours before it lies overhead. It thus rises six hours earlier, at 9pm.

      

#4. If the Moon is currently in the waning gibbous phase, what phase will it have in seventeen to eighteen days (five-eighth of a lunar month) from now?

full new
waning gibbous waxing crescent
third quarter first quarter
waning crescent waxing gibbous

The Moon orbits once around the Earth every lunar month (a lunar month is 29 days in length). With every orbit, it shifts through the entire sequence of phases. It thus takes three and one-half days (one-eighth of the lunar month) to change its appearance from one of the eight major phases to the next. In eighteen days, the Moon will shift through five major phases. It will then appear to us in the first quarter phase.

      

#5. If the waning crescent Moon rose nine hours ago, what time of the day or night is it?

midnight (12am) noon (12pm)
early morning (3am) afternoon (3pm)
dawn (6am) dusk (6pm)
morning (9am) evening (9pm)


The Moon is in the waning crescent phase when it appears partly illuminated from Earth, in the days before a new Moon (with each passing night, a little bit less of the Moon will be illuminated). It will be located on the same side of the Earth as the Sun, moving around from the side to in front of the Earth. When we are underneath this point we are on the side of the Earth illuminated by from the Sun, so it must be daytime. The waning crescent Moon will lie directly overhead when we are rotated an eighth of the way around before noon. This occurs three hours earlier, at 9am. The Moon will rise six hours before it lies overhead. It thus rises six hours earlier, at 3am. If the Moon rose nine hours ago, it is now noon.