Project #2: Observing

ASTR 10, Vista College, Spring 2004

Instructors: Dr. Korpela

Project #2: Observing -- Due May 6, 2004

This assignment is worth 10% of your final grade. You must start early in order to fully complete this assignment. Although this assignment is not due until May 6, THERE WILL BE NO EXTENSION IF THE WEATHER IS UNCOOPERATIVE DURING APRIL, so it is essential that you begin NOW and take advantage of any good weather in March!

A critical part of the scientific process is making your own observations. From observations one must then draw appropriate conclusions and report their results. To help you gain an appreciation for this you can make simple observations of the stars and the Moon as a good example.

You will need to keep an observing log (which should be turned in with your writeup). You should collect these observations into a single notebook that you will hand in at the end of the project. Be careful to include all the information requested. Simple sketches are sufficient, but you may be as artistic as you want with the sketches and observations. You may also take photographs if you so desire (there is a danger here that they won't turn out).

Besides the observation notebook you should also turn in a discussion of your results. There are 3 main sections: Stars, Moon, and Saturn. In your discussion please make sure you answer all of the questions in each section below. Base your answers on your observations! Correct answers that conflict with your observations will not receive full credit.

If you are unable to find a safe location from which to make night observations, please see me soon.

Learning your way around the sky

Choose a location where you will have an un-obstructed view of the sky to the East, South, and West (roof of a tall building, peak of a hill or mountain, or a large clearing). Ideally, you should make your observations exclusively from this location for this assignment. But if you often find yourself far from this location, make your observation anyway, and note the different location in your observations. Be sure and discuss the effect this has on your results if you do this.

Take advantage of clear weather! It may not happen often, so you shouldn't pass up any clear skies.

Recall that you can (crudely) measure angles on the sky using your outstretched arms. Your fist (on outstretched arm) covers about 10 degrees on the sky, while a single finger covers about 1 degree, and your outstretched hand (fingers spread) covers about 18 degrees on the sky. To familiarize yourself with angles on the sky, do the following: Go out during the evening and find Orion the hunter (look for the 3 stars in a row in his belt). You might use the star chart on the back of your textbook to help you. If you need further assistance, please let me know.

Measure and record the angular width of Orion's belt. (In other words, estimate its size in degrees, and tell me how you did this and what the result was).
Measure and record the angle between the upper left star (Betelgeuse - red supergiant) and the lower right star (Rigel - blue supergiant) in Orion.
Measure the angle between the upper left star and Saturn (a fairly bright yellow star that is currently about as far above the top of Orion as the distance from Rigel to Betelgeuse).
Make a sketch of Saturn's location relative to the bright stars nearby (including those of Orion).

Observing the Moon

Starting now, shortly after sunset is a good time to observe the Moon. Beginning no later than March 22nd, you should observe the Moon at approximately the same time for 2 weeks (or until it is no longer visible at that time). Then you should alter your observing time appropriately. You should continue to observe the Moon until about April 25 (or until you have covered at least an entire lunar cycle). You should observe every-other day/night if you can. Each observation will only take you a few minutes. On at least one day/night you should observe the Moon twice, a few hours apart.

You should record the following things for each observation:

Location of Observation
Time (note PST or PDT) and Date of Observation (What do you think you should do about the change to Daylight Savings Time?)
Weather Conditions at that Time and Location (cloudy, foggy, clear, etc.)
Assuming you can see the Moon, record the Moon's position with respect to the compass directions on the horizon (North, East, South, and West), and its approximate altitude.
The Moon's phase with a sketch and a name (i.e. crescent, gibbous, quarter, etc.).
The Moon's position with respect to bright stars in the sky (the Sun counts as a bright star). Include a sketch and/or name the constellation in which the Moon is located (at night). Estimate the angle between the Moon and the Sun (if possible).

If the weather is foggy and you cannot make an observation at that time record that information.

In what direction (if any) does the Moon move with respect to the horizon in the course of a few hours?
In what direction (if any) does the Moon move with respect to the stars and constellations from day to day?
What physical motions causes each of these apparent motions?
Was the Moon always up at the time of your observations?
Did the Moon's phase change with its position in the sky (relative to the horizon) over the course of a single night?
Did the Moon's phase change with its position in the sky (relative to the stars) from night to night?
Is the Moon sometimes visible throughout the day? Explain using your observations to support your conclusion.
What time of day does the Full Moon rise?
What time of day does the First Quarter (western half lit) Moon set?
What causes the Moon's phases? Explain the variation in lunar phases with pictures and words.

Observing the Stars

On a clear night you should make the following observations:

Find the Big Dipper (look north). Remember that the second star in the handle (Mizar) is a binary star! Use the two end stars of the "bowl" as pointer stars. Extend the line between them to find Polaris, the North star. Polaris is (very roughly) about 30 degrees from the pointer stars (which are about 5 degrees apart).
Measure and estimate the altitude of Polaris. The altitude is the angle between Polaris and the horizon.
Sketch the relative positions of the Big Dipper and Polaris (relative to the horizon).
Go out a few hours later and repeat the previous two measurements.

In your writeup, consider the following:

Did the altitude of Polaris change between the two observations?
Did the relative positions of the Big Dipper and Polaris change between the two observations?
What physical motion causes this apparent motion in each case? If there is no motion, explain that.
The latitude of Berkeley is 38.8 degrees. How does this compare with the altitude of Polaris?
They should be the same. But observations are not always accurate! Please tell me two things about your observation that could potentially make your measurement of Polaris' altitude incorrect.

Saturn Revisited

During the last week or two of the assignment, repeat your earlier measurement of Saturn's position.

Measure the angle between the upper left star and Saturn (the brightest "star" in the sky right now).
Make a sketch of Saturn's location relative to the bright stars nearby (including those of Orion).

In your report, address the following questions:

Has the position of Saturn relative to the stars changed? If so, in what direction did Saturn move relative to the stars.
What physical motions explain this observation?

General Questions to Consider

What did you do about the change to Daylight Savings Time?
How did this affect your observations and/or conclusions?
If you could not always observe from the same location, discuss how this affected your observations and/or conclusions.
What did you learn in this project that you did not know before?