Due: April 16 (but don't procrastinate)
You must do at least one lab, but can do more for extra credit (how much credit depends on how good a job you do, and is up to your TA). If you have a different project you would like to do, get approval from your TA.
In these labs you will get to watch the sky and see for yourself some of the phenomena we have been talking about in class. You will need to make observations on several clear days, so you will not be able to put this off until the last minute, because the weather may not cooperate. Therefore, strange as it seems, you must get started on this right away. When writing up the lab, first describe what you were trying to accomplish, and what you expected to see. Then describe your method, including how you collected your data, and give your result. Finally, describe what you saw. Explain clearly the astronomical events which caused the events you witnessed. Given what you know, do your results make sense? The part of the report where you explain why you saw what you saw constitutes half of the grade on this lab; the observations are the other half.
The Setting Sun
This requires that you to choose one place where you can see the sunset on at least 4 days (more are desirable) when the sun is visible while setting. One possibility is the bridge between Birge and LeConte. For best effect, a few days should pass between each observation (although it never hurts to have more observations). DO NOT look directly at the sun until it is at least three--quarters gone, and preferably only through sunglasses then. On each occasion make a sketch of the horizon with landmarks and indicate where the sun went down. Mark the time as well. Try to be as precise with both as possible. If you like, compare your time with the prediction in the paper. Don't forget to explain carefully why the sun appeared to move along the horizon. Was it going north or south? How would this vary at different times of the year?
The Sun's Path
In this experiment, you will need to measure a shadow cast by the Sun at the same time on at least 4 days (more are desirable). For best effect, a few days should pass between each observation (although it never hurts to have more observations). You can use a vertical stick (eg. flat--bottomed pen or pencil) to create a shadow on a flat piece of paper. Each time you observe the sun, mark on the sheet of paper where the tip of the shadow falls. You should be careful to line up the paper exactly the same each day. On at least one day, make measurements at several different, well separated times so you can trace the arc of the sun's shadow. How does the length of the Sun's shadow change at a given time of day, and from day to day? Give a careful explanation of why it is changing, and why it gets longer or shorter. How could you use the shadow of the Sun to find North? Optional: Is the shadow shortest exactly at noon by your watch (or the Campanile)? What happens when we go to Daylight Savings Time?
Phases and Positions of the Moon
The idea here is to follow the Moon along part of its orbit. Measure its position with respect to the sun or some stars on at least 3 nights (and these should be close to each other). Draw the phase as best you can each time. To measure the position, you have several possibilities. You can measure the angle of the moon above the horizon at a fixed time or the time when the Moon appears to pass a fixed reference (like a corner of a building or a tree branch). Or you can try to measure it with reference to a nearby star (say along the extension of the shadow line on the Moon). Finally, you could try to measure its angle with respect to the sun, either directly during the day, or by noting its position at sunset, or by noting the time difference between sunset and moonrise or moonset. Why do you see what you see? (Remember, the Moon is sometimes up during the day, sometimes at night. You should be able to figure out when to look by what phase it is.)
The Orbital Motion of the Earth
This is to be seen by measuring the change in the position of stars at a fixed time of night. You can either use the time when a star sets, or when it passes a fixed reference point attached to the ground (like a building or tree). Good choices would be the bright stars in Orion, Sirius, or Capella (see your book). The Earth turns 15 degrees per hour, and the stars rise 4 minutes earlier each day. Your measurement will have to be fairly precise, and it helps to have several days pass between measurements. Make at least 3 measurements. By what angle did the stars move per night? In which direction? Why do you see what you see?
The Orbital Motion of Mars
Mars is an early evening object in the West. Measure its position with respect to the ground, sun, or stars. Use the methodology of (3) or (4), and make at least 3 measurements. Is it moving apparently further from or closer to the sun? By how much per day? Is that rate constant (should it be)? Does the Earth's motion affect your results? Why do you see what you see? You should get started on this right away, as it will be setting earlier and earlier. See if you can find a place on the Web which helps you locate the planet (or use your CD-ROM).