ASTRO 101 Lab: Moon Phases

Objective: Determine the relationship between the positions of the Earth, Moon, and Sun over several observations. Pre-Lab Questions: 1. What do you expect will happen to the Moon’s appearance over your observation period? As a result of how the Earth and Moon orbit the Sun, as well as the fact that the Earth rotates once every 24 hours, the Moon's appearance and position fluctuate over time . The Moon, in fact, is spinning even though we always see the same side of it. 2. How does the location of the Earth, Moon, and Sun at any given time relate to the phase of the Moon seen? Because the moon is illuminated by the Sun, the moon's appearance is influenced by the Sun's position in relation to the Earth. The Moon, Earth, and Sun are all roughly on the same line when a new Moon occurs. They are all on the same line at a full Moon, but because the Moon is on the other side of the Earth, the sun illuminates the entire moon sidefacing us. When only a section of the bright moon is reflected, waxing and/or crescent moons occur. Procedure: 1. Over the next two weeks, observe the Moon on at least 5 different days. 2. For each observation, make a sketch on the lab sheet showing how the Moon appears in the sky and label it with the name of the phase. 3. For each observation, record the date and time of day (including am or pm) the observation was made, as well as the number of days since the previous observation. 4. For each observation, describe approximately where in the sky the Moon is located. (For example, “low in the sky in the southeast”, “on the western horizon”, or “high in the sky towards the south”.) Also give a basic description of any features visible on the Moon and note any changes from previous observations. 5. For each observation, include additional notes that are relevant or of interest (weather conditions, apparent size on sky, etc.). 6. For each observation, place the Moon on the diagram in the appropriate location and label it with the date of the observation. 7. Study the sketches, notes, and diagrams you have completed and then answer the questions at the end of the lab. SketchDate/TimeLocationNotes Date:____________ Time:____________ Circle one: am pmYour location (city, state): Moon location in Sky: Features: Other Notes: Date:____________ Time:____________ Circle one: am pm # Days Since Previous Observation:_______Your location (city, state): Moon location in Sky: Features: Other Notes: Date:____________ Time:____________ Circle one: am pm # Days Since Previous Observation:_______Your location (city, state): Moon location in Sky: Features: Other Notes: Date:____________ Time:____________ Circle one: am pm # Days Since Previous Observation:_______Your location (city, state): Moon location in Sky: Features: Other Notes: Date:____________ Time:____________ Circle one: am pm # Days Since Previous Observation:_______Your location (city, state): Moon location in Sky: Features: Other Notes: Questions 1. What was the total length of your observations (i.e., how many days between the first and last observations)? 5 days 2. Over the total time of your observations, describe how the appearance of the Moon changed (be specific). Over time of my observations, the appearance of the moon became less visible. The shadow of the moon grew closer to the half which would later become the last quarter 3. With references to your observation notes and the diagram you completed, explain how the location of the Moon relative to Earth and the Sun are related to what you observed. The Sun lights up different sides of the Moon as it orbits around Earth and it's the part of the Moon from which our eyes see reflected sunlight that determines the lunar phase. 4. Were any changes in the features on the Moon noted? Explain your observation, referring to the Moon’s orbit and rotation. Yes.

For each observation of the Moon that you make, mark the location of the Moon relative to the Sun and Earth (as looking down on the North Pole) by making a large dot on the outer circle in the appropriate location. Label the dot with the date of the observation. Phase Diagram