ASTRONOMY MOON PHASE PROBLEMS

There are there variables dealing with the phases of the moon. They are: 1. Local Time 2. Phase 3. Position You will be given two of the variables and will have to solve for the third one.

Keep in mind that you always measure the moon to the East of the sun. The diagram represents the celestial sphere with the Earth in the center. The horizontal line is the horizon. The location of the moon and the sun are indicated on each diagram.

1. The moon is in waxing crescent phase and it is on the meridian. What is the local time? Answer: In the waxing crescent phase the moon has moved 45 degrees to the east of the sun. If the moon is on the meridian, the sun must be 45 degrees above the western horizon which make the local time 3:00PM.

2. The moon is in full phase and is 45 degrees above the western horizon. What is the local time? Answer: When the moon is in full phase the moon and sun are in opposite sides of the sky or 180 degrees apart. If the moon is 45 degrees above the western horizon, the sun must be 45 degrees below the eastern horizon which makes the local time 3:00AM.

3. The moon is in waning gibbous phase and the local time is 9:00PM. Where is the moon? Answer: At 9:00PM the sun is located 45 degrees below the western horizon. To be at the waning gibbous phase the moon must move 225 degrees to the east of the sun. That puts the moon on the eastern horizon or just rising. 4. The moon is in third quarter phase and the local time is 6:00AM. Where is the moon? Answer: At 6:00AM the sun is located on the eastern horizon or just rising. To be in third quarter the moon must move 270 degrees to the east of the sun. That puts the moon on the meridian.

5. The moon is just rising and the local time is 9:00AM. What is the phase of the moon? Answer: At 9:00AM the sun is located 45 degrees above the eastern horizon. If the moon is on the eastern horizon, the moon had to move 45 degrees to the east of the sun. This makes the phase to be waxing crescent.

6. The moon is on the meridian and the local time is 9:00PM. What is the phase of the moon? Answer: At 9:00PM the sun is located 45 degrees below the western horizon. If the moon is on the meridian, the moon had to move 135 degrees to the east of the sun. This makes the phase to be waxing gibbous.