Astronomy 16 – Astrophysics: Stars, ISM, and Galaxies
Archive of Assignments
Homework assignment 1 [pdf] is now posted. It's due on Wednesday at 5pm.
When you have a chance, read over this Word document containing some follow-up notes about our first lab.
Read the assignment for class 2 [pdf]. Note that you have to solve the last two problems of the four pages I handed out in class on Tuesday. Here are scans of the readings from the textbook: pp. 29-34, pp. 50-53 and 74-75, p. 73, pp. 61-62, and pp. 78-80 [all pdfs]. And here is the handout/problem we did in class [pdf] (drawing a circular orbit superimposed on a highly eccentric orbit) along with my solution [pdf].
We'll discuss on Thursday in class the actual methods and chronology of the human discovery of the scale of the Solar System. As mentioned in Tuesday's class, the ancient Greeks measured the size of the Moon relative to the Earth by looking at the shadow of the Earth on the Moon during lunar eclipses and noting the relative radii of curvature, as shown in the single image of a lunar eclipse and more easily seen in a time-lapse:
You can see from these images that the Earth is between three and four times the size (radius) of the Moon. Also note that as Venus orbits the Sun, it has visible (with a telescope) phases and that it never strays too far from the Sun.
To prepare for our first class, on Tuesday, read assignment 1 [pdf] and think about the points I raise in it. There are three very short things for you to read in that assignment: Bennet pp. 90-92, 98 [pdf], first approximate derivation of the expression for centripetal acceleration, second derivation.
Read the information about lab 1: imaging at the Peter van de Kamp Observatory [pdf]. Reading related to the lab: Ryden and Peterson, first few pages of Ch. 1 [pdf] and A short introduction to astronomical image processing.
There is a short (two problems) homework assignment [pdf] due on Monday by 5 pm. That's the day before our first class meeting. To help you think about the material in this assignment, watch this short (34 second) video.
Look over these images and movies of the recent solar eclipse and think about this: When we say the Moon and Sun appear to be the same size, what is it, exactly, that's the same about their sizes? Certainly not their diameters or radii in kilometers.
credit: Richard Sparkman
An assignment to help you prepare for the first class meeting will be posted here about a week before classes start.
Do what you can to see the solar eclipse on August 21. It will be partial in Philadelphia but the path of totality stretches from Oregon to South Carolina.
Return to the main class page.
This page is maintained by David Cohen
dcohen1 -at- swarthmore.edu
Last modified: September 16, 2017