101 Astronomy Online Lunar Phases and Eclipses Lab
Name Nate Christensen
Introduction: Your project for the semester involves tracking the phases of the Moon to determine what is known as the synodic period or the time it takes the Moon to go through all of its phases. In this lab, you will use Starry Night and an animation on the web to reinforce what you learned in the lessons, seeing how the different lunar phases relate to the positions of the Earth, Moon, and Sun. We'll also use Starry Night to look at some simulated eclipses. Procedure: Start up Starry Night. Open the "Find" dialog box to find the list of objects in the solar system. Double-click on the sun to center and lock it (allow Starry Night to change the time, if necessary). Use the pull-down menu next to the sun entry and select "Go There". You should now find yourself at 0.019 au from the Sun (recall that an au is an Astronomical Unit, where the average distance from the Earth to the sun is 1 au). Doubleclick on Earth in the Planets List to center and lock on to Earth (again, allow Starry Night to reset the time if it needs to). Zoom in until the field of view is 1' x 1' (1' = 1 arcminute, 1/60 of a single degree). Notice that the time is now expressed in UT - universal time. UT is the time in Greenwich, England, the location of the Prime Meridian. Set the time to 18:00 UT and hit the stop button. 1. Which part of the Earth is experiencing daylight? (Give a geographical description.) The Western Hemisphere 2. For which part of the Earth is it night? The Eastern Hemisphere 3. What time is it in Illinois (valid choices here are "midnight", "sunrise", "noon", or "sunset")? Noon 4. What time is it in Mandalay, Burma (almost exactly on the opposite side of Earth from Illinois; use the same choices as in question 3)? Midnight Set the time step to 3 minutes. Click on the play button and watch the Earth. 5. With the north pole near the top of the image you see, is the Earth rotating clockwise or counter-clockwise? Counter-clockwise 6. What time of day is it at each of the positions a, b, c, and d in the figure at the right? Use the terms "midnight", "noon", "sunrise" and "sunset". Assume that you are looking down at the north pole of the Earth. A. Sunset
B. Noon C. Sunrise D. Midnight The Earth's Moon: The Moon is roughly 1/4 the size of the Earth. However, the EarthMoon distance is much larger, about 60 times the size of the Earth. You may have noticed that at a 1' field of view, the Moon is not likely to be visible. Since it is impractical to make a scale model of the Sun/Earth/Moon system, we'll just have to make due with an out of scale model. Go to the following website: http://www.astro.uiuc.edu/projects/data/MoonPhases/index.html If you don't see the image with the Sun on the left, Earth in the middle, and the Moon on an orbit around the Earth, you may not have a flash player installed on your computer. Click on the 'FAQ/HELP' link at the top of the page and follow the instructions given there. Click on the 'Start' button and watch the Moon go through its phases as it orbits the Earth. Once you've watched at least one full set of phases, click on the 'Stop' button. Click on the 'Set New Moon' button to return the Moon to its starting position. 7. Run the animation again, stopping it as needed. Watch for the following phases to appear: New Moon, Waxing Crescent, Waning Crescent, First Quarter, Third Quarter, Waxing Gibbous, Waning Gibbous, and Full. The diagram below is labeled with the positions of the Earth, Sun, and several different positions for the Moon, labeled 1 - 8.
For each position of the Moon in the diagram, write down the phase of the Moon and a brief description of how it appears from the Earth. For the description, include one of the following terms: 'left side illuminated' 'right side illuminated', 'no illumination', 'less than
half illuminated', 'half illuminated', 'more than half illuminated', and 'fully illuminated'. Be sure also to state whether the illumination is on the right or left side of the Moon. Position Phase Description 1 New Moon No illumination 2 Waning Crescent Left side illuminated/Less than half 3 Third Quarter Half illuminated/left side 4 Waning Gibbous Left side illuminated/More than half 5 Full moon Fully illuminated 6 Waxing Gibbous Right side illuminated/More then half 7 First Quarter Half illuminated/right side 8 Waxing Crescent Right side illuminated/Less than half 8. Notice now that as the Moon orbits the Earth, approximate rise and set times are given. Fill in the chart below, using the following terms: "sunrise", "noon", "sunset", "midnight". Phase New Moon First Quarter Full Moon Third Quarter Rise 6:00 A.M. 12:00 A.M. 6 P.M. 12:00 P.M. 6 P.M. 12:00 P.M. 6 A.M. 12:00 A.M. Set
Determine the time of day at which each of the following events will occur. For each answer, choose one of the following: "between sunrise and noon", "between noon and sunset", "between sunset and midnight", or "between midnight and sunrise". Crescent Waxing Moon Rises Waning Crescent Moon Sets Waxing Gibbous Moon Sets Waning Gibbous Moon Rises Between sunrise and noon Between sunset and midnight Between midnight and sunrise Between noon and sunset
Eclipses: The sun is the light source for all objects in the solar system. When one object passes in front of another such that the sunlight is blocked, we say that an eclipse is occurring. A solar eclipse occurs when the Moon blocks light from the Sun from reaching the Earth. A lunar eclipse occurs when the Earth blocks light from the Sun from reaching the Moon. 9. During which phase of the Moon can a solar eclipse occur? New Moon During which phase of the Moon can a lunar eclipse occur? Full Moon
Let's return now to Starry Night and start with a lunar eclipse. Click on the Home button to return to Earth. Use the pull-down menu next to your location to set the location to "Champaign, USA (with reset)." (Note: If you haven't already set the home location to Champaign, just choose whatever it has as the default but make sure that whatever location you choose includes the "with reset" option.) Set up the following conditions: Date: 3/3/2007 Time: 10:00:00 PM Daylight Savings Time: Off Location: Velletri, Italy Time Step: 1 minute Time Flow: Stopped Zoom in so that the field of view is 1 x 1 . Open the "Find" dialog box again (if it isn't still open) and double-click on the Moon to center and lock on to it. Click the play button and run it until it reaches approximately 4:30 in the morning. 10. Describe what you have just seen. A total lunar eclipse The darkest part of the shadow is known as the umbra. The lighter shadow around the umbra is called the penumbra. 11. At what time did the leading edge of the Moon enter the umbra? Between 10:35 and 10:40 12. At what time did the Moon completely leave the umbra? At about 2:15 13. How long was the Moon completely within the umbra? (Hint: This is not the same as the amount of time between questions 11 and 12.) Right around an hour As you've probably already guessed, the event you just witnessed was a total lunar eclipse. If only part of the Moon moves through the umbra, we call it a partial lunar eclipse. If the Moon only passes through the penumbra, we call it a penumbral eclipse. Now, set up the following parameters: Viewing Location: 14 N, 28 E, Time Zone: +2 Date: 10/3/2005 Time: 7:15:00 AM Daylight Savings Time: On Hide Daylight not selected (you want to see the daytime sky here) Make sure that your view is zoomed out to the largest field of view. Scroll around the sky so that you are looked due east. Just south of due east, you should find the sun and Moon. Put the cursor over the sun and right click. Select the option to 'Centre'. Click on the play button and watch the sun move across the sky.
14. Describe what you have just watched. Was there any noticeable change in the light level due to the motion of the Moon? The moon totally covered the sun and the suns light was not as intense making it more dim. Now, take a more detailed look at what you've just witnessed. Change the time to 1:28 PM. In the "Find" window, double-click on the Moon. Zoom in so that your field of view is now 4 x 4 . 15. What kind of eclipse is this? Be specific (remembering that there are several kinds of lunar and solar eclipses). Partial solar eclipse In the "Find" window, use the pull-down menu next to "The Moon" and select "Show Info". Open up the information for "Position in Space" and record the moon's "Distance from observer". 16. What is the distance to the Moon in kilometers? 390,028 km Now, change the viewing location to 21 N, 14 E, Time Zone +1. Use the "Find" window again. Double-click on the Moon and zoom again to a field of view of 4 x 4 . 17. How do the Moon and sun appear now? How is it possible that the view appears so different when your viewing position has changed by such a small amount? The moon now does not completely cover the sun anymore because although it seems as if we only traveled a small amount the conditions were just not right at that location. Reset the date to 3/29/2006. Set the time to 7:30 AM. Zoom out as far as you can. Use the "Find" menu again to center on the sun. Click the play button and watch as the sun moves across the sky. 18. Describe what you have just watched. Was there any noticeable change in the light level due to the motion of the Moon? I just witnessed a total eclipse, and when the moon was completely in front of the sun all you could see was a ring of light making it pretty much completely dark out. Reset the time to 12:02 PM and set your field of view to 4 x 4 . 19. What specific kind of eclipse is this? Total Eclipse Use the pull-down menu for the Moon to pull up its information. 20. What is the distance to the Moon in kilometers? 354468 21. Compare your answers for 15/16 with your answers for 19/20. Do your answers make sense based on what you have learned about the different types of eclipses? Explain. Yes because were closer to the moon so it completely covers the sun rather than partially.