A221 Lab #2 : The Night Sky

Handed out: September 9, 2009

Due (in class): December 7, 2009


The rules: All aspects of this project should be completed individually. While everyone is required to make their own notes and write their own report, you may make arrangements with your classmates to meet as a group for the observing sessions. Questions about this policy (and about the lab itself) should be addressed to the AI or to the professor.

NOTE: You must have at least 7 observations for part (3) to be considered for full credit for this lab (at least 4 observations are necessary to receive partial credit).

The goal: This laboratory exercise will require you to track the motions of the stars during the course of the semester. The first part of the lab is an obligatory trip to Swain Hall's rooftop for an evening observing session. We will provide an orientation to the night sky at that time. Subsequent observations will be done on your own (or with other students).

(1) [15 pts] Attend one of the two roof top observing sessions scheduled for mid-September (keep track of the weather! We will only re-schedule if both nights are rained out). During the observing session, sketch Scorpio, Cygnus, and Casseopia.

(2) [15 pts - must be done in both September and again in November for full credit] Find the north star. Make a sketch of the Big Dipper and Little Dipper at the time of your observation. Make certain to note the cardinal directions (and general orientation information) on your sketch and date and time of day (night) of the observation.

(3) [50 pts] Monitor the rise and set of the constellations. Decide on a constellation to track early in the semester [NOTE: both of the Dippers are excluded from this part of the assignment since you are tracking them in (2)]. Ideal constellations are: Andromeda, Pegasus, Casseopia, Cygnus. Arrange to observe the night sky approximately every two weeks at approximately the same time of night each session. Sketch the location and orientation of the constellation for each observing session. How does its location change as a function of time?

(4) [20 pts] Imagine that you are an astronomer in 47 B.C. Give 2 different (scientific) reasons for why you think the earth is round. How would you measure the radius of the earth using "current" (for 47 BC) technology? How would you measure the radius of the earth today (2009 A.D.)?