LunaPhasesLab

Name: Lunar Phase Simulator – Student Guide Part I: Background Material Go to NAAP labs and open “ Lunar Phases” then answer the following questions after reviewing the “Background Material” pages for the simulator. Page 1 – Introduction to Moon Phases Is there a dark side of the moon? (Note: this question can be effectively answered either yes or no, so it is important to explain your reasoning.) Yes, one side of the moon is always shaded (2pts) How long does it take the moon to complete one cycle of phases, in days? ___29 and a half days (29.53)_____(1pt) If the moon is full today, what phase do you expect it to be at in a week? ____3rd quarter_____(1pt) How about one month later? ________full moon_____ (1pt) Many words in astronomy also non-astronomical uses as well. Using your knowledge of how the terms on the left are used in astronomy match them with the non-astronomical uses on the right. (2pts) waning convex, rounded -- also hunch-backed, having a hump gibbous to increase in size, quantity, volume, intensity, etc. waxing decrease in magnitude, importance, brilliancy, intensity, etc.

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Page 3 – The Time of Day Go to NAAP labs which you downloaded on your computer. Open Lunar Phases and under Simulators, use “Moon Phases and the Horizon Diagram” to determine the direction of the earth’s rotation when viewed from above the North Pole. (Hint: rotate the observer – the stickfigure – to the noontime position, then sunset position, then midnight position, and finally back to sunrise position. The earth has made one complete rotation and the observer has experience one daily (diurnal) cycle of day and night.) When viewed from above the North Pole, does the earth rotate clockwise or counter- clockwise? __________________ (1pt) Page 4 – Rising and Setting 1. When the moon crosses the western side of the horizon plane it is rising / setting (circle). When it crosses the eastern side of the horizon plane it is rising / setting (circle). (1pt) 4

Page 5 – The Horizon Diagram Describe the location of the moon in the sky of the horizon diagram at bottom (Moon Phases and the Horizon Diagram- Simulation Page). Use direction words (like north, west, etc.) and estimate its altitude in degrees. (2pts) Part II: Visualizing Phases Question 1: We can determine the appearance of the moon based on the orientation of the moon and sun with a simple heuristic. In the figure below, bisect the moon twice . a) Draw a line (perpendicular to the direction of sunlight) that shows the half of the entire moon that is illuminated and shade the shadowed region. b) Draw a line (perpendicular to the Earth-moon line) that shows the half of the moon visible for an observer on earth. c) Mark the region that is both visible from earth and illuminated by the sun. That region will be the phase of the moon we on earth see. (2pts) We normally draw the phases of the moon with the terminator (the dividing line between light and shadow) from the north pole to the south pole of the moon. This is how the moon would be seen if it were on the observer’s meridian. We can use the drawing above to determine the amount of illumination and whether it is on the left or right hand side of the moon. Use the drawing above to draw the appearance of the moon in the box below. 5 Moon Earth sunlight

● The sun and moon on the globe can be dragged around. ● In the Diagram Options panel, the show angle option shows the earth-moon-sun angle. The phases are technically defined in terms of this angle. ● In the Diagram Options panel, the show lunar landmark option draws a point of reference to more easily observer lunar rotation and revolution. ● In the Diagram Options panel, the show time tickmarks option displays the time of day of the observer. Earth – Moon – Sun Geometry Question 2: Click on the option labeled show angle – which graphically displays the angle between the direction of the sun and moon. Now drag the moon around the sun to a variety of different locations and note the appearance of the Moon Phase. Describe how the value of the angle correlates with the appearance of the moon. (2pts) Question 3: Each row on the following table shows diagram of the earth-moon system. For each diagram, find the age of the moon at that position (that is, the time 7

passed since new moon), its phase, and its percent illumination. Finally, make a sketch of its general appearance. You may use Microsoft word feature to paint the sketch or print the page, use a pencil to sketch then take a picture or scan and paste. You will need to take into account the orientation of the sunlight – it is different in each diagram from the orientation in the applet. The first row is completed for you. You may need to rotate your paper and hold it up to the screen to check your answers. The last one has been done for you as an example. (8pts) Moon Geometry Age Phase Percent Illumination Sketch 8

e) third quarter f) waning crescent Question 5: If a moon is between 50% and 100% illuminated it is a… a) crescent moon. b) gibbous moon. c) new moon. d) full moon. Question 6: During a new moon what percent of the moon’s entire surface (irrespective of how much we can see) is illuminated by the sun? a) 0% b) 25% c) 50% d) 75% e) 100% Question 7: What is the phase of the moon depicted here? a) new b) first quarter c) third quarter d) full Question 8: If the moon is at its highest point at 12 AM… a) it rose at about 6 AM and will set at about 6 PM. b) it rose at about 6 PM and will at about 6 AM. c) it did not rise earlier, it was always in the observer’s sky that day. d) it rose earlier at 12 PM and will set the following 12 PM. Question 9: What is the time of day depicted in the figure to the right? a) 12 AM b) 6 AM c) 12 PM d) 6 PM Question 10: If it is noon and a new moon for a particular observer a second observer on the opposite of the earth 10 sun

a) will see a full moon. b) will see a new moon. c) won’t see any moon in the sky at all. Question 11: During the course of an evening… a) the moon basically stays at the same phase. b) the moon will go through 2 phases. c) the moon will go through 3 phases. d) the moon will go through all 8 phases. Question 12: Approximately how much time has elapsed between moon 1 and moon 2 in the figure above? a) 3 hours b) 6 hours c) 1 day d) 4 days e) 7 days f) 14 days Question 13: Over the course of a month, about how much of the moon’s surface can be photographed? a) 25% b) 50% c) 75% d) 100% 11