The Moon's Orbit: Worksheet #1

Fall 2005

ASTR 110L, Sec. 2

Name: ________________

Date	First side	Second side	Total diameter	Average diameter

09/07/05	________________	________________	________________
	________________	________________	________________
	________________	________________	________________	________________

09/14/05	________________	________________	________________
	________________	________________	________________
	________________	________________	________________	________________

10/05/05	________________	________________	________________
	________________	________________	________________
	________________	________________	________________	________________

10/12/05	________________	________________	________________
	________________	________________	________________
	________________	________________	________________	________________

10/19/05	________________	________________	________________
	________________	________________	________________
	________________	________________	________________	________________

11/09/05	________________	________________	________________
	________________	________________	________________
	________________	________________	________________	________________

11/16/05	________________	________________	________________
	________________	________________	________________
	________________	________________	________________	________________

12/07/05	________________	________________	________________
	________________	________________	________________
	________________	________________	________________	________________

(see other side for instructions)

INSTRUCTIONS

As explained in the handout, you measure from the midpoint of the scale to each side of the Moon's disk, and add these values to get the total diameter. The form on the other side of this page has places to record the measurements to each side separately. Do the measurements and write down the two separate values in the spaces provided; you can add them up later.

Repeat your measurement three times! Repeated measurements yield better accuracy; they also give you a better chance of spotting any errors you may have made.

The example below shows how to fill in the blanks on the other side, using measurements made for the observation shown in Fig. 1 of the handout. Note that the sums listed in the table are all in pretty good agreement, even though the individual measurements to the two sides are not. Getting three total diameters this close requires good technique -- if conditions are not favorable, it may be quite hard to make such accurate measurements.

Date	First side	Second side	Total diameter	Average diameter

02/20/03	5.8	5.7	11.5
	4.6	6.8	11.4
	6.4	5.2	11.6	11.5

Finally, take the average of your three total diameters for each night to get an average value. If all three measurements are good, this average is probably the most accurate value. On the other hand, if one of your measurements is obviously wrong, exclude it and just average the other two.

Joshua E. Barnes (barnes@ifa.hawaii.edu)

Last modified: September 7, 2005
http://www.ifa.hawaii.edu/~barnes/ASTR110L_F05/moonorbit_WS1.html