Name:
TG
Ivanhoe Girls’ Grammar School
Unit 1 Astronomy – Moon Observation Activity
This exercise is designed to help you make some observations of your own and from them draw some
conclusions about the moon’s appearance and its motion through the sky. You can use binoculars or
a telescope if you have one. However, naked eye observations will be more than adequate to complete
this exercise.
Please do not refer to any books or computer programs. Consider yourself to be an amateur
astronomer who is doing this for the first time.
All of your analysis/conclusions must be based upon your own observations.
http://www.atnf.csiro.au/research/AboriginalAstronomy/
(Aboriginal moon phase rock carving at Ngaut Ngaut, SA)
Use the following chart and descriptions to assist you with your observations.
Describing the Moon’s phases.
Crescent Moon
when we can see only a sliver of the moon's disk (the side of the moon facing us)
Full Moon
when the moon's disk is light because the Earth is between the sun and the moon
Gibbous Moon
when we can see roughly three-quarters of the moon's disk
Half Moon
(also called quarter moon) when we can see one half of the moon's disk (this is onequarter of the entire moon's surface)
New Moon
when the moon's disk is dark (and invisible to us) because the moon is between the sun
and the Earth
Quarter Moon
(also called half moon) when we can see one half of the moon's disk (this is one-quarter
of the entire moon's surface)
Waning Moon
when the moon seems to be getting smaller, going from full to gibbous to half to
crescent to new
Waxing Moon
when the moon seems to be getting bigger, going from new to crescent to half to
gibbous to full
Over the next five weeks you will need to make regular observations of the moon’s position in the sky and
of its appearance.
To assist you with your observations you could consult the newspaper for the moons rise and set times.
Directions to students:
Step 1
As part of your observations you will need to record the date and time of each observation. In the
appearance circle sketch your view of the moon. This includes how much of it is illuminated, and the angle
that the illuminated portion is at.
On the second diagram place a cross for where you think the Moon’s position is in the sky relative to the
Earth and Sun. Also draw a tangent line on the Earth to represent your position at the time the observation
was made. The ‘S’ indicates the South Pole.
Below is an actual observation provided as an example for you.
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Step 2
When you get to a full moon in your observations, use the angulator to determine an approximate value for
the angular size of the Moon. You should make your measurement when the Moon is high in the sky, not
low on the horizon.
Moon’s angular size:
o
Why should this measurement be made when the Moon is high in the sky and not low on the horizon?
Questions
Question 1
Can the Moon only be seen at night?
Question 2
What evidence did you observe that proves that the Moon is a source of reflected light and that it is not a
luminous body?
Question 3
Based on your observations, in what direction does the Moon go around the Earth?
Question 4
Based on your observations, approximately how long did it take for the Moon to complete one orbit around
the Earth?
Question 5
What can you say about the position of the Sun, Earth and Moon when there is a full moon? Include a
sketch as part of your answer.
Question 6
What can you say about the position of the Sun, Earth and Moon when there is a new Moon? Include a
sketch as part of your answer.
Question 7
Did the appearance of the significant features on the Moon’s surface change/move during the course of your
observations?
Question 8
Based on your answer to Questions 7 and 3 what two things can you say about the Moon’s rotation about its
own axis?
Conclusion
Write a brief summary of what you have learned from this activity.
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