Objectives: The purpose of this lab is to get you to understand the phases of the moon and the relationships between the Sun, Earth, and Moon.
I. Night and Day
For the first section of this lab you will be pretending that your head is the Earth (the North Pole will be the top of your head, and the South Pole will be under your chin), and a light bulb will be the Sun.
SETUP: (Yes you really need to do this — but don’t worry, it’s fun, and easy!) You will need a fairly dark room (the darker the better!) with one bright lamp at about head level while you are standing or sitting. A single bright, uncovered light bulb works best.
1.
Stand (or sit) facing the light bulb (Sun). The diagram below illustrates this setup as seen from above your head, so from above the North Pole of the Earth. Which of the lettered locations indicates the position of a person who lives on the end of your nose?
abcdef
2.
Which of the lettered locations indicates the position of a person who lives on your left ear?
A
B
C
D
E
F
Not visible from this vantage point
3.
Let’s say you wanted to shade in the night side of Earth in the above diagram. Which of the numbered diagrams below shows the night side of Earth properly shaded in?
1
2
3
4
4.
As seen from above the North Pole, the Earth rotates counter-clockwise. Refer to the lettered locations in the first diagram at the top. Indicate the places on your head where it is the following times of day:
noon
sunset
midnight
sunrise
no time — this is the lightbulb, not a location on your head
5.
What time of day would it be for a person that lives on the end of your nose when you are directly facing the light bulb?
12am midnight
3am
6am (sunrise)
9am
12pm noon
3pm
6pm (sunset)
9pm
6.
Turn your body in place a quarter circle to the left (counterclockwise as viewed from the top down), but do not move the lightbulb. Now the light bulb should be off your right ear. Now what time is it for someone who lives on the end of your nose?
12am midnight
3am
6am (sunrise)
9am
12pm
noon
3pm
6pm (sunset)
9pm
7.
Turn your body another quarter turn to the left. Now the light bulb will be directly behind you. Now what time is it for someone who lives on the end of your nose?
12am midnight
3am
6am (sunrise)
9am
12pm
noon
3pm
6pm (sunset)
9pm
8.
Turn your body another quarter turn to the left. Now the light bulb will be off your left ear. Now what time is it for someone who lives on the end of your nose?
12am midnight
3am
6am (sunrise)
9am
12pm
noon
3pm
6pm (sunset)
9pm
II. Moon Phases
Now we are going to examine the phases of the moon. Hold up a small ball to represent the moon at about head level, taking care not to block your view of the side of the ball facing you with your fingers. (Ideally, if you have access to a small styrofoam ball with a small hole in it, place this ball on the tip of an upright pen or pencil, so none of the ball’s surface is blocked.) You will be holding the Moon out at arm’s length and describing its appearance at different points in its orbit. You will turn around in place, keeping the moon at arm’s length, to simulate the orbit of the Moon (the ball) around Earth (you). The light from the lightbulb will simulate sunlight. Stand as far away from the lightbulb as possible, still staying within your otherwise dark room, and make sure you can turn in place all the way around without hitting anything with your outstretched arm.
Below is a diagram, as seen from above your head (above the Earth’s North Pole), of the Moon’s orbit around the Earth. (Note: it is NOT drawn to scale.) In this diagram the Earth rotates (spins) counter-clockwise in place, and the Moon orbits the Earth in a counter-clockwise direction. Each of these motions are shown with arrows. To represent that the sun is very far away, the sunlight is represented as arrows coming in from off the side of the diagram. You will notice eight different numbered positions in the moon’s orbit that we will be examining in this exercise: Each location corresponds with a different “phase” of the moon, as listed immediately below the diagram.
9.
Copy the diagram above onto a blank piece of paper. Make it nice and large so you have plenty of room to annotate it. Now shade the “night” side of the Earth as seen from space high above the North pole of the Earth, which is the perspective of the diagram. Leave the “day” side of Earth blank. Which of the lettered diagrams below shows how the Earth should be shaded?
Type the letter of your answer in the box here:
10.
Now label the “noon”, “midnight”, “sunrise”, and “sunset” points on the Earth in your diagram. This is a summary of what you should have already figured out in the questions in Part I, above.
Which of the lettered locations on the zoom-in diagram of Earth below best represents each of those times?
Type one letter for each:
Noon:
Midnight:
Sunrise:
Sunset:
11.
Does the number of moons shown in the diagram correspond to the number of moons that are orbiting the Earth in real life? EXPLAIN in one or two sentences.
12.
In the diagram you have drawn on your paper, shade in the “night” side of the MOON, leaving the day side blank, for each of the numbered positions 1-8 of the moon in its orbit, as seen from space above the Earth and Moon. Use the same perspective as the diagram here (repeated from the top of this page), which you should have previously copied onto your paper.
For each numbered circle, indicate which of the lettered options below best matches how you shaded that circle, using the same perspective as the diagram above.
Type one letter for each 1: 2: 3: 4: 5: 6: 7:8:
Letters may be repeated or not used at all.
13.
Now comes the main part — and the fun part! — of this exercise, where you will actually SEE the phases of the moon directly.
Using your head (Earth), ball (Moon), and light bulb (Sun) model, you will simulate the Moon at different places in its orbit and see what the phases look like directly. Starting with the Moon at position 1, follow the Moon through one orbit around the Earth by physically turning your body counterclockwise (left) in place, and see what the moon looks like at each position. (Make sure the shadow of your head doesn’t fall on the moon at position 5 — that would be an eclipse! That doesn’t happen most months.) Here is a video clip of a person demonstrating.
Shade in the dark portion of each circle so it matches the appearance of the Moon as seen from the Earth at the eight positions in the diagram.
For each circle, indicate which of the lettered options above (A through N) best matches how you shaded that circle to represent how you saw it in your physical simulation.
Type one letter for each 1: 2: 3: 4: 5: 6: 7: 8:
Letters may be repeated or not used at all.
14.
In a few sentences, describe how the apparent shape of the moon changes during one orbit as seen from the Earth. Include in your explanation: (a) Which side of the Moon (left or right) is illuminated during the various stages? (b) How does the apparent amount of illumination change over time? (c) Do the physical size and shape of the Moon change during its orbit?
III: Times of Visibility
Now you will investigate what times of day the different phases are visible from Earth. The diagram you have been creating on paper will be your most useful tool for answering the questions that follow. If you have not done it already, be sure you have the day/night shadows drawn on Earth and Moon, the times of day labeled at the different locations of Earth, and the names of the different phases labeled on the diagram. A quick glance at this diagram will tell you immediately what time of day (or night) a given phase is high overhead. For the phase in question, just look at the time of day it is on the location on Earth directly under that phase. That is the time when that phase is high overhead, because an observer standing at that location would have to look nearly straight up to see that phase of the moon. Several hours later, the moon will still be in that phase, but the Earth (and the observer standing on it) will have rotated counterclockwise, so the moon will not be high overhead for that observer anymore. As viewed by that observer, the moon will have appeared to move lower in the sky, on its way to setting. For help visualizing this, or with any of the questions that follow, experiment with the interactive animation at http://astro.unl.edu/naap/lps/animations/lps.html. You can advance the animation by pressing “start/pause animation”, or you can increment the animation one hour (or minute, or day) at a time.
15.
Approximately how long does it take for the moon to complete one orbit around the Earth? Pick one:
1 hour
1 day (24 hours)
1 week
1 month (a “moonth”)
16.
How many phases will the Moon go through in that time?
17.
About how long does it take the Earth to spin once on its axis? Pick one:
1 hour
1 day (24 hours)
1 week
1 month (a “moonth”)
18.
How many phases will the Moon go through in that time? AND How far will the moon have moved in its orbit? Explain in one sentence or so.
19.
As viewed from Earth, what is the one PRIMARY reason that the moon rises and sets in our sky? Explain in one sentence.
20.
Between one rising and subsequent setting, approximately how long is the moon visible in the sky at a time? Pick one:
A) 1 hour
B) 12 hours
C) 24 hours
D) 1 week
E) 2 weeks
F) 1 month
21.
Now you will put together everything you have learned from the previous sections in order to figure out when each moon phase rises, sets, and transits through its highest point in the sky. This is one of the biggest parts of this lab! It will take some time and effort to figure it out. Be sure to use the hints at the beginning of this section, and your answers to earlier questions. If you get stuck, please consult your instructor ASAP. Keep in mind that the moon rises and sets in our sky just like the sun does (as do the stars and galaxies we can see from Earth!) and for the same reason — because the Earth spins on its axis. So the Moon is visible for approximately 12 hours at a time on any given day, just like the sun is. However, WHICH 12 hours it is visible varies throughout the lunar cycle, as the moon is in different parts in its orbit with respect to the Sun and Earth, and is therefore often in a different part of the sky than the Sun.
At what time of the day would the New Moon be high overhead? (Technically the moon is never directly overhead — we are looking for the time of day when the moon is highest in the sky. For an observer in the northern hemisphere, it would be located toward the South.) We call this time the transit time for the Moon. At what time does the First Quarter Moon transit? The Full Moon? The Third Quarter Moon?
To answer these questions, hold the moon ball out in your hand at the position in question, say First Quarter. Then turn your head to determine what time the Moon rises and sets for a person who lives on the end of your nose (look at where the sun is to figure out the time, referring to your diagram if necessary). Record your answers to the transit questions in the table below, then fill out the rest of the table by determining the rise and set times of the four listed phases.
Your answer choices for all twelve boxes are “noon”, “sunset”, “midnight”, and “sunrise”. Spelling counts!
Lunar Phase | Moon rise time | Moon transit time | Moon set time |
First Quarter |
|
|
|
Full Moon |
|
|
|
Third Quarter |
|
|
|
New Moon |
|
|
|
22.
Could you see the First Quarter Moon at Sunrise?
yes
no
23.
Could you see the First Quarter Moon just before midnight?
yes
no
24.
Could you see the Third Quarter Moon at Sunset?
yes
no
25.
Could you see the Third Quarter Moon just after sunrise?
yes
no
IV: Eclipses
An eclipse can occur when the Sun, Earth, and Moon line up. A lunar eclipse is when the Moon passes into the Earth’s shadow, and a solar eclipse is when the Moon’s shadow falls on the Earth. Still using your head to represent Earth, ball to represent Moon, and lightbulb to represent Sun, act out both types of eclipses. Use your direct observations of simulating these two processes to answer the following four questions.
26.
At what moon phase(s) can a lunar eclipse occur? Check all that apply.
A) new moon
B) first quarter
C) full moon
D) third quarter
E) none of these
27.
At what phase(s) can a solar eclipse occur? Check all that apply.
A) new moon
B) first quarter
C) full moon
D) third quarter
E) none of these
28.
Having simulated each of these types of eclipses with your model Moon, which type was easier to make? Based on this, which type do you think would be seen by more people on Earth? Explain why.
29.
Why don’t we see solar and lunar eclipses every month? Explain in several sentences. Need a hint? Check here.orhere.
V. Viewing the Earth from the Moon
Imagine for a moment that you are an astronaut standing on the surface of the Moon and you can see the Earth from where you are standing.
Refer to your diagram to help you visualize this situation for the questions below.
30.
Would the Earth appear to have phases as viewed by an astronaut on the Moon?
yes
no
31.
If an astronaut on the Moon currently observes a waxing gibbous Earth, what would someone on Earth see when observing the Moon? Describe in one sentence or so.
32.
If the Moon is in the first quarter phase as viewed from Earth, in what phase would an astronaut on the Moon observe for Earth?
A) new Earth
B) waxing crescent
C) first quarter
D) waxing gibbous
E) full Earth
F) waning gibbous
G) third quarter
H) waning crescent
33.
Develop an easy way to figure out the Earth’s phase given the lunar phase OR the lunar phase given the Earth’s phase. Describe your system below.
34.
If an observer on Earth is observing a total solar eclipse, what would an astronaut on the side of the Moon facing Earth see? Describe thoroughly in 1-2 sentences.
35.
If an observer on Earth is observing a lunar eclipse, what would an astronaut on the side of the Moon facing Earth see? Describe the whole event from start to finish, including everything the astronaut on the Moon would see and how long it would last. Aim for 2-3 full sentences.
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