Physics 131: Survey of the Universe
Spring 2004

Prof. Michael S. Vogeley
Department of Physics
Office: 811 Disque Hall
Phone: 215-895-2710
Office hours: Tuesday 2:00-3:30 p.m. or by appointment

Teaching Assistant:
Heather Rave
Department of Physics
Office: 813 Disque Hall
Phone: 215-895-2720
Office hours: Wednesday 11:00 a.m. - 2:00 p.m., or by appointment

Course Meetings
Course Description and Philosophy
Textbook and Reading Assignments
Homework Assignments
Class Participation
Homework Hints
Homework Solutions
Midterm Solutions
Course Schedule


FINAL EXAM: Wednesday, June 9, 3:30-5:30 p.m. The exam is closed book and covers material from the entire course, though with more emphasis on the second half. A formula sheet will be provided. Bring a calculator.

Welcome to the home page for Physics 131: Survey of the Universe! Watch this space for important announcements and useful hints. Plan to use email to ask questions about homework assignments and the course readings so that we can give you timely feedback and send any relevant homework hints to everyone else in the class.

Course Meetings

Lecture times: Tuesday and Thursday 12:30-1:50 in Curtis 451 (a.k.a "Cardiac Heights")
If you will be unable to attend class, please notify us ahead of time or contact us as soon as possible. If you miss class, you are responsible for seeing one of your classmates for lecture notes.

Office hours: see above for office hours of the instructor and teaching assistant.


This web page is the syllabus. If you're reading a printed copy, you can find the web page at You should check this for updates!

Course Description and Philosophy

Using instruments that range from backyard telescopes to satellites launched by NASA, astronomers use light from distant objects to learn about our universe, and use physics and mathematics to interpret their observations and develop theories about the formation and evolution of planets, stars, galaxies and even the entire universe itself. Astronomy cannot tell us WHY we're here, but it helps to tell us WHERE we are, and gives us some clues to HOW we got here. How did the Earth, Sun, and Galaxy form? What is the future of our Universe?

This course is designed to introduce Astronomy to non-physics majors. Emphasis will be on understanding of important concepts, backed up by simple quantitative analysis. No calculus will be used in this class. However, knowledge of basic high school level mathematics such as algebra and geometry will be assumed. A review of mathematical concepts will be distributed in class. Please review these notes immediately and see the instructor or TA if you have questions.

Topics that will be covered in this course include

Have fun and ask lots of questions! I hope that this course stretches your imagination.

Textbook and Reading Assignments

Required reading for the course is "Astronomy Today, Fourth Edition" by E. Chaisson and S. McMillan (Prentice-Hall), ISBN 0-13-091542-4. This text was written by two leading educators and researchers in Astronomy,

Please read the assignments before class and prepare to ask questions.

See the Course Schedule below for the weekly reading assignments.


Grades will be based on the following weighting of different components of the course:
Homework: 25%
Presentations: 15%
Midterm Exam: 20%
Final Exam: 30%
Class Participation: 10%

The following sections of the syllabus describe each of these components.

Homework Assignments (check for hints below)

There will be 8 homework assignments. These will be due at the beginning of class on every Thursday except during the first week of class and during the week of the midterm exam. Late homework will not be accepted. Never. No excuses. Your lowest homework grade will be dropped, so you're already covered for one "emergency." You may not submit your homework by email.

Solutions to the homework will be handed out in class on the due date (and posted on the web page), which is why late homework will not be accepted. Please strive to present your answers in a neat, workmanlike fashion; the clarity of your solutions will count toward your grade. You must show your work, clearly backing up your answers with calculations where necessary, to get full credit.

Brainstorming is fun! (Even Einstein received help.) But you and you alone are responsible for the work that you turn in. Please write up your own solutions to the problems. Breaches of this policy will result in homework scores being divided by the number of ``participants.'' Second offenses may result in failure (of the class).

Homework 1: PDF file
Due at 12:30 p.m. in class Thursday, April 8
Homework 2: PDF file
Due at 12:30 p.m. in class Thursday, April 15
Homework 3: PDF file
Due at 12:30 p.m. in class Thursday, April 22
Homework 4: PDF file
Due at 12:30 p.m. in class Thursday, April 29
Homework 5: PDF file
Due at 12:30 p.m. in class Thursday, May 13.
Homework 6: PDF file
Due at 12:30 p.m. in class Thursday, May 20.
Homework 7: PDF file
Due at 12:30 p.m. in class Thursday, May 27.
Homework 8: PDF file
Due at 12:30 p.m. in class Thursday, June 3.


During the second half of the quarter, roughly ten groups of five students will make 15-20 minute presentations to the class on an assigned topic. You should prepare a few slides (or other multimedia, if you choose) to illustrate your talk. Everyone in the group can take part in the presentation or you can elect just one or two to actually give the talk. Everyone in the group will receive the same grade for the presentation, so start thinking now about who you would like to work with.

See the handout "Class Presentation Guidelines" for more details. For your group assignment, see the handout "Class Presentation Groups". I will distribute a class list with faces and email addresses to facilitate identifying group members.


We'll have one Midterm exam and a Final. The Midterm will be given during class time on Tuesday, May 4.

The Final will be during exam week and will include material from the entire course, but with some emphasis on the second half of the course.

Both exams will be closed book. Bring a calculator. However, you may not preprogram your calculator with memorized formulae. Ask me if you are uncertain about this policy.

Class Participation

The more you put into the course, the more you'll get out of it, and that includes participting in class discussion. Ask questions! And bring in any articles you find that discuss Astronomy - we'll try to discuss them. The Class Participation component will be partially based on attendance.

Homework Hints

Hints will be posted here as I think of useful info or in response to your questions.

Homework 1:
Problem 6: You are asked to compute the parallax of a star that is 5 lightyears away. The "parallax" is the angular distance that the star appears to move in the sky when seen from two different positions of the Earth. Try drawing a little diagram. Imagine that first you observe the star in, for example, June when the Earth is on one side of the Sun. Six months later, in December, you observe the same star again, but now you're on the other side of the Sun. Draw a line between those two positions of the Earth - they're 2 A.U. apart (where one Astronomical Unit is 1.5 X 108 km). Suppose that the star lies 5 light years away from the Sun along a line that is perpendicular to the first line. Now, connect the star's position to both Earth positions. You've just drawn a triangle, where the base of the triangle has the two Earth positions at the corners, and the star is at the third corner. The parallax is half the interior angle in the star's corner.

In class, we discussed how, at large distance, the angular size is angle = (physical size)/(distance) X (360)/(2 pi) degrees Try thinking of our triangle above from the standpoint of the distance star, and use this formula to compute the parallax. Think carefully. What are the relevant physical size and distance in this case?

Homework 2:
Problem 2: Try to solve this using ratios of the masses and radii and use the table on p. 146 of the textbook, which lists the radii and masses of the planets and Moon in terms of Earth's radius and mass.

Problem 3a: There is some overlap in dates when they lived, so you could use their birth years to sort them.

Homework Solutions

Problem set solutions will appear here shortly after the homework is due.

Midterm Solutions

Solutions will be posted here after the midterm exam:
<-- Midterm solutions (PDF file) -->

Course Schedule

Please note the following schedule of readings (in Astronomy Today) and assignments (due at the beginning of class each Thursday). This schedule will be updated, so check the web page!

Week Class Dates Reading Homework Exams
1 March 30, April 1 1.1-1.5
2 April 6, 8 2.1-2.7 HW1 due
3 April 13, 15 3.1, 3.3, 3.4 3.5, 4.1, 5.1, 5.2, 5.6 HW2 due
4 April 20, 22 6.1-5, 9.1-2, 9.5, 10.1-2, 10.4-5 HW3 due
5 April 27, 29 16.1, 16.5, 17.1, 17.3-5, 17.7-8 HW4 due
6 May 4, 6 20.1-4 Midterm (May 4)
7 May 11, 13 21.2-5, 22.1, 22.5-8 HW5 due
8 May 18, 20 21.1-3, 23.6-7, 24.1-3, 24.5 HW6 due
9 May 25, 27 26.1-6 HW7 due
10 June 1, 3 27.2, 4, 5 HW8 due
11 June 7-12 Final Exam Week

Last update: May 26, 2004