Astronomy Lab Report PHSC 1001C: Earth Science       Name: ________________________   Date: _________________________   Instructor: ______________________       Purpose: To explore why Earth experiences seasons and why we see phases…

Astronomy Lab Report
PHSC 1001C: Earth Science

Name: ________________________

Date: _________________________

Instructor: ______________________

Purpose: To explore why Earth experiences seasons and why we see phases of the moon.

Astronomy Lab Part 1: Why does Earth experience seasons?

1. Open up the Seasons interactive.

Take a few minutes to familiarize yourself with the different components of this interactive animation.

• At the top of your screen, you should see a diagram of Earth’s orbit around the sun. A white “X” on the rotating Earth indicates the location of someone standing at 45 degrees north latitude.

• In the lower right corner of the orbit window is a diagram showing the angle of sunlight that hits Earth at that time of year at that latitude.

• To the far right of the orbit window is a thermometer indicating the average temperature at that time of year at that latitude. 

• Finally, below the orbit window, you should see an image of the landscape at that same latitude at the time of year on the orbit window.

   

1. Allow the animation to run for one full orbit of the Earth around the sun without changing any of the initial settings (the angle of inclination should be zero degrees).

1. Looking at the landscape view, describe the path of the sun in the sky throughout the year (you can click on “Trace Sun’s Path” in the control panel to make this easier to discern).

2. Describe any changes in sunlight angle in summer, spring, winter, and autumn.

3. Describe any changes in average daily temperature in summer, spring, winter, and autumn.

    

1. Change the inclination angle to 23 degrees (this is Earth’s actual angle of inclination). Let the animation run for a full orbit of the Earth around the sun.

1. Describe the path of the sun in the sky throughout the year (again, you can click on “Trace Sun’s Path” in the control panel to make this easier).

    

2. Describe the changes in sunlight angle in summer, spring, winter, and autumn.

3. Describe the changes in average daily temperature in summer, spring, winter, and autumn. 

4. Do these simulated observations correspond with your real-life experience of average temperatures in these seasons? Why or why not?

1. Leave the inclination angle at 23 degrees but move the Earth (you can “drag” it with your cursor) to its winter solstice position. As you move the Earth around its orbit, you will see labels appear in the lower left-hand side of the orbit window. Hit “stop” when you are in the winter solstice position. Using the landscape window, approximate the number of hours of sunlight and night.

1. Sunlight hours:

2. Night hours:

1. Leave the inclination angle at 23 degrees but move the Earth to its summer solstice position (see lower left of orbit window for that label). Using the landscape window, approximate the number of hours of sunlight and night.

1. Sunlight hours:

2. Night hours:

1. Leave the inclination angle at 23 degrees but move the Earth to its autumnal and then spring equinox positions (see lower left of orbit window for that label). Using the landscape window, approximate the number of hours of sunlight and night during each of those days.

1. Autumnal equinox sunlight hours:

2. Autumnal equinox night hours:

3. Spring equinox sunlight hours:

4. Spring equinox night hours:

1. Do these simulated observations of day/night hours correspond with your own real-life observations of day/night length at different points in the year? Why or why not?
2. If you lived in the southern hemisphere on Earth, how would these observations change?

1. Now change the inclination to 35 degrees. What do you observe throughout the year?

1. Move Earth to its winter solstice position.  Change the inclination angle until you find the smallest angle for which a full day passes with no sunlight. What angle is this?

Analysis: Many people believe that seasons on Earth are caused by Earth being closest to the sun in summer and farthest from the sun in winter. In at least 2 paragraphs and citing resources to support your arguments, explain why this is not the case and what actually causes us to experience seasons on Earth.

Astronomy Lab Part 2: Why does the moon go through phases?

Open up the Lunar Phases interactive.

Take a few minutes to familiarize yourself with the different components of this interactive animation.

o   On the left side of your screen, you should see a top-down view of the Earth-moon system from far above the North Pole. The sun is off-screen to your right. 

o   An observer is positioned on the surface of Earth.  For all of the activities below, you are to pay attention to what the observer can see.  The observer can only see what is above him/her in the sky.

o   On the right part of your screen is a view of the landscape for that observer on the surface of Earth.

o   Below this landscape panel are a clock and a calendar indicating the time and date.

1. Pause the time and then change the time to noon. Describe the position of the observer relative to the sun. Does this position make sense to you? Why or why not?
2. Now change the time to midnight. Describe the position of the observer relative to the sun. Does this position make sense to you? Why or why not?
3. Let the interactive move forward in time for a full month. (Note that the dates change on the calendar as 24 hours pass.) During this time, watch the moon move around the Earth. About what percentage of the total moon is always in shadow (shaded blue)?
4. Position the moon such that it appears to be a full moon for the observer on Earth (lunar phases, as they change, are noted at the top of the screen). 

1. How much of the total moon is in shadow (shaded blue)?

1. How much of the lit part of the moon is visible to the observer?

1. Approximately when does the full moon rise and set in the sky?

1. Position the moon such that it appears to be a new moon for the observer on Earth.

1. How much of the total moon is in shadow (shaded blue)?

2. How much of the lit part of the moon is visible to the observer?

3. Approximately when does the new moon rise and set in the sky?

    

1. Position the moon such that it appears to be a first quarter moon for the observer on Earth.

1. How much of the total moon is in shadow (shaded blue)?

2. How much of the lit part of the moon is visible to the observer?

3. Approximately when does the first quarter moon rise and set in the sky?

1. Position the moon such that it appears to be a third quarter moon for the observer on Earth.

1. How much of the total moon is in shadow (shaded blue)?

2. How much of the lit part of the moon is visible to the observer?

3. Approximately when does the third quarter moon rise and set in the sky?

    

    

   Analysis: Many people believe that the phases of the moon are caused by the Earth blocking some of the light from the moon. In at least 2 paragraphs and citing resources to support your ideas, explain why this is not the case and what actually causes us to see the phases of the moon.