Lunar Phases PDF

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Solved Assignment Lunar Phases...

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ASTR 120 – Fall 2020

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Lab 2 - Lunar Phases Part 1 – Lunar Phases and Eclipses Procedure: During the course of a month, the appearance of the moon changes, from fully illuminated (full moon) to completely dark (new moon) and back again. This sequence of lunar phases can be explained if we make the following assumptions: • • • •

The Moon is spherical in shape. The Moon is visible only by reflected Sunlight. The Moon circles the Earth once per month. The Moon’s orbit around the earth in which one full revolution of the moon around the earth takes 29.5 days from new moon to new moon.

The major phases of the lunar cycle are considered to be: • The full moon (100% of the moon’s face appears lit to Earthlings) • The new moon (None of the moon’s face appears lit to Earthlings) • The quarter moons (during which half of the moon’s face appears illuminated). The quarter moon following the new moon is called the first quarter moon (To Earthlings, it appears lit on the right side) and the quarter moon following the full moon is called the third quarter moon (To Earthlings it appears lit on the left side). 1.

Sketch & Label – Using the worksheet, “Phases of the Moon Worksheet”, sketch all four of the major phases of the moon. Full New 1st quarter 3rd quarter Show which sides of the moon are sunlit and which side is in shadow for each of the four phases. Shade in the darkened sides of the Moon with a pencil. Note that the Earth is already shaded for day/night. Note: Be sure that you are shading in the dark areas as viewed from above the solar system. A common mistake is for students to give the “Earth view” of the phases on this diagram, when what is asked for is the “Top view” (view from space).

2. Is the full moon between the earth and sun or on the other side? No, the full moon is on the other side.

3. Where is the position of the moon during new moon compared to its position during full moon? The New moon is between the Earth and sun, and the full moon is up there

4. Imagine the Moon is directly between the Earth and the Sun, is this event a lunar eclipse or solar eclipse? Solar Eclipse

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5.

What is the phase of the moon during this event? Full Moon

6. If a total lunar eclipse occurs when the moon passes through the Earth’s shadow, what is the phase of the moon during a total lunar eclipse? Full Moon

7. Now consider the 1st Quarter phase and how it appears to you on Earth. Which of the following images best represents the appearance of the moon during first quarter (as viewed from the Northern Hemisphere of the Earth)? Circle your choice and explain your reasoning.

The First Quarter Moon is often called a Half Moon because we can see exactly 50% of the Moon's visib surface illuminated. The First Quarter Moon is a primary Moon phase when we can see exactly half of the Moon's visible surface illuminated.

The other lunar phases (crescent, gibbous): At any point between the four major lunar phases, the name of the moon’s phase is determined by how its appearance as seen from earth is changing. Between New and Full Moon, the illumination is increasing from night to night, so the Moon is said to be waxing. Similarly, between Full and New Moon, the illumination is decreasing or waning. Between third quarter and first quarter, less than half of the Moon is illuminated, so the Moon is crescent-shaped. Between first quarter and third quarter, more than half of the Moon is illuminated, so the Moon has a gibbous shape. 8. Using the model of the moon’s phases we have developed, determine where the moon is halfway between 3rd quarter and new moon and sketch here what the moon will look like during this time below:

Waning Crescent

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Waning 8. What is this phase called? (_________ + _________) Crescent

(Choose from: waning, waxing, full, new, first quarter, last quarter, crescent, gibbous.)

11. About how many days between a new moon and the next new moon? Is there a unit of time about this long? 29.5 days

12. About how many days between a new moon and the 1st quarter moon? Is there a unit of time about this long? 7 days

13. Does a lunar eclipse happen every month/every full moon? (Yes or No.) Why or why not? Explain. No, because the Moon's orbit is tilted five degrees from Earth's orbit around the Sun. Without the tilt, lunar eclipses would occur every month. Lunar and solar eclipses occur with about equal frequency.

Part 2 – Rising and Setting Times Objective:

To develop a geometric top-view model for how the rising and setting times of the moon are related to the phases of the moon. To be able to figure out and predict the times of moonrise, moonset, and transit (passage overhead) for different phases of the moon based on the model for the moon’s orbit developed during Part 1.

1) Modeling A Typical Day on Earth For the moment, consider just the Earth and Sun in this model. As the Earth rotates (counterclockwise as seen from above the North Pole), you should see that someone on earth will see the Sun rise and set during one rotation of the earth (a period of time commonly referred to as a “day”).

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Sunrise

Midnight

Noon

Sunset

1. Sketch & Label - In the figure above, label the points on the earth where someone is currently experiencing the following: • • • •

“noon” (when the Sun appears directly overhead). “midnight” (when we are facing directly away from the Sun). “sunrise.” “sunset.

2) Which Direction is Which At Various Times of Day? E Sunrise

Horizon line W

2. Sketch - In the diagram above draw and label a small “stick figure” representing a person at the sunrise position. Make sure that your stick figure has his/her feet on the Earth and is not standing on his/her head.

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3. Sketch – Draw a horizon line. A horizontal line between the feet of the person and the surface of the Earth, i.e. a tangent line. 4. Sketch - Label E and W indicating the directions of east and west for the person in the above diagram.

5. How did you determine the direction of east? Of west? Because in the morning, pointing with the left arm to the sun is East, and pointing with the right arm is West.

3) Modeling the Rising and Setting Times of the Moon midnight 6. If the full moon is “transiting” (passing overhead), what time is it? __________

Hint: In order to figure out when the moon is rising, find the spot on Earth where that moon is overhead. Then back up the clock by six hours. Noon 7. When the full moon is “rising,” what time is it? _________

8. When the full moon is “setting,” what time is it? _________ Sets at sunrise 6:00 am West 9. Where in the sky (east or west) is the full moon at around sunset? _________

around sunrise? _________ East

6:00 am 10. When the new moon is “rising,” what time is it? _________

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*** Phases

of the Moon Worksheet *** Diagram of the Moon’s orbit (as viewed from over the North Pole: TOP VIEW)

FULL MOON

1ST QUARTER

3RD QUARTER

NEW MOON...