In the space below, write an explanation for why we observe phases of the moon, based upon your current knowledge:

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1 IDS 102 Phases of the Moon PART II In the space below, write an explanation for why we observe phases of the moon, based upon your current knowledge: As you discovered yesterday, when we observe the Earth from a spaceship directly above the North Pole, we will see the Moon move around the Earth in a -wise direction. This is an important perspective for the animations we will be using simulating the Earth and Moon positions. Earth N Moon To investigate the Phases of the Moon, we will use two approaches: 1) A light bulb (optional), a ball that is white on one side and black on the other and a partner to help you. Assume that your head is the Earth and the ball is the Moon. Your partner will move the white/black ball around you so that the white part of the ball is always toward the light bulb (the Sun), or a direction you designate to be the sun s direction. The dark part is always away from the light. This is the unlit side of the moon. As the Earth, you slowly spin on your axis. How long does it take Earth to make one rotation? 2) A computer animation from the University of Nebraska:

2 Make sure you can see Moon Phase, Horizon Diagram, and the time tickmarks (should look like the image above) In the upper right corner of the screen is the phase panel. This will illustrate how the Moon appears from the Earth. Notice that when the web page first opens, the Moon phase is a New Moon. In the lower right corner in the Horizon Diagram, which is a Celestial Sphere view of the moon and sun relationships as they move across the sky. You can click on start animation or you may click on days and hours to move the Moon around the Earth. TAKE SOME TIME TO GET TO KNOW THIS WEBSITE!!! PLAY AROUND BEFORE YOU BEGIN ANSWERING QUESTIONS PAY ATTENTION TO CHANGES ON ALL PARTS OF THE WINDOWS AS THE MOON ORBITS THE EARTH ASK QUESTIONS IF YOU ARE CONFUSED ABOUT WHAT YOU ARE SEEING

3 Move the Moon to the first quarter phase as noted on the web site. How many days after the new Moon is the first quarter? Sketch below how the Moon appears from the Earth- in other words, what you would see in the sky (shade the dark area of the Moon). Move the Moon in the animation to the last quarter phase. How many days after the first quarter phase is the last quarter phase? Again, draw the appearance of the Moon from your point of view on Earth. Get your partner to help you determine position of the Sun, Earth and Moon for the first quarter phase and the last quarter phase using the ball and light. For these two phases, what is the difference in the appearance of the Moon from the Earth? Complete the orbit of the Moon around the Earth. Using both the days and hours button, determine how long it takes the Moon to orbit the Earth once. How long does this orbit take?

4 ECLIPSES Eclipses are all about shadows in space. The Moon casts a shadow on the Earth or the Earth casts a shadow on the Moon. A solar eclipse occurs when the Moon casts a shadow on Earth, and we cannot see the Sun. A lunar eclipse is when the Moon is in the shadow cast by the Earth. During which Moon phase must a solar eclipse happen? During which lunar phase does a lunar eclipse happen? Eclipses are scheduled to happen this year on: June 1 Partial Solar eclipse (E. Asia, northern N. America, Iceland) June 15 Total Lunar eclipse (S. America, Europe, Africa, Asia, Australia) July 1 Partial Solar eclipse (S. Indian Ocean) Nov 25 Partial Solar eclipse (S. Africa, Antarctica, Tasmania, New Zealand) Dec 10 Total Lunar eclipse (Europe, E. Africa, Asia, Australia, Pacific, N. America) The next Total Solar Eclipse will be on Nov. 13 th, 2012 and will be visible from N. Australia and the South Pacific. Totality will last for 4 min. 02 sec. Notice that eclipses do not happen every time the Moon orbits the Earth. What ideas do you have to explain this? Talk to an instructor about your ideas before continuing.

5 The orbit of the Moon is not in the same plane as the plane of the Earth s orbit around the Sun (the Plane of the Ecliptic), therefore only sometimes do the Sun, Earth and Moon happen to be in the same line, not every time the Moon orbits the Earth. Often the full or new moon is above or below the Plane of the Ecliptic. Draw the arrangement of the Sun, Earth and Moon in the space below for the full Moon phase. (Notice that we are seeing only half of the Moon during a full Moon phase, but this is the full surface that we can see from Earth.) Draw the arrangement of the Sun, Earth and Moon for the new Moon phase. Use the white/black ball and light to confirm that you understand the difference between a full Moon and a new Moon. A couple of important definitions: Waxing Moon: the appearance of the Moon between the new Moon phase and the full Moon phase. The lit part of the Moon appears to get larger each successive day with a waxing Moon. Waning Moon: the appearance of the Moon from the full Moon phase to the new Moon phase. The lit part of the Moon appears to get smaller each successive day with a waning Moon.

6 In the arrangement of the Sun, Earth and Moon illustrated below, where would one see a waxing Moon? A waning Moon? Label these areas on the diagram. Sun E Determine which of the Moon illustrations below is waxing and which is waning: (We suggest using the light, ball, and your partner to help you on this question). Waxing or waning? Waxing or waning? What logic did you use to determine your answers? As you use the animation, you will notice times that the Moon appears to be a thin sliver (called a crescent Moon) and times when the Moon is larger than a quarter Moon, but smaller than a full Moon (called a gibbous Moon). Draw on the illustration below (we are looking at the north pole of the Earth) the positions of the waxing crescent, waning crescent, waxing gibbous, and waning gibbous Moons. Sun E

7 For review and to insure that you understand the positions of the various phases, 1. List the eight phases we have described thus far, beginning with the New Moon. List the phases in the order in which we would see them over the course of one revolution of the Moon about the Earth: 2. locate the positions of those eight phases in the drawing below (again, our view of the Earth is directly at the North Pole). E Sun Check with an instructor before proceeding!

8 End of module Questions: When the Moon looks like this draw the position of the Sun, Earth, and Moon in the space below: When the Moon looks like this draw the position of the Sun, Earth, and Moon in the space below:

9 How much of the Moon is being illuminated by the Sun when the Moon appears like the illustration below? Explain why we see the Moon as illustrated above: waxing or waning waxing or waning How could you tell the difference? Is the following Moon waxing or waning?

10 For each of the Moons below, determine the position of the Moon, Earth, and Sun, the phase of the Moon, and what the Moon would look like 7 days later: position of Sun, Moon, and Earth waxing or waning name for this phase what will the Moon look like 7 days later? When we observe the Moon, we always see the same side of the Moon. (Our first observation of the far side of the Moon was when a satellite took photographs of the surface in the 1960 s). Does the Moon rotate on its axis? Explain your reasoning.

11 The following statements are either true or false. If the statement is true, defend your choice in the space below. If the statement is false, state why the statement is false. 1. A waxing gibbous Moon phase will be a few days before the full Moon phase. 2. When the Moon appears as it does below, it is possible to have a lunar eclipse: 3. The time of day we expect to see the following phase of the Moon is in the early morning, such as 5 or 6 AM.