Physics 172
Spring 2026

Stellar Astronomy & Cosmology 

Course Materials:

• Week 0: 1/21-23                  Intro to Astronomy [Ch. 1, 2]
  Physics 172 syllabus
  Wednesday, January 21: Lecture 1: Course structure, science & astronomy, units & notation.
  Wednesday, January 21: Lecture Notes: SI units, speed of light, light year.
  
  Friday, January 23: Lecture 2: Distances with c, scientific notation, length scales, Erastosthenes.
  Friday, January 23: Lecture Notes: Light years, exponents, and trigonometry.
  
  Problem Set #1, due Friday, January 30, 2026 (hard copy, due in-class)
  
  
  
• Week 1: 1/26-30                  Basic Physics I: Motion and Orbits [Ch. 2, 3]
  Monday, January 26: Class cancelled due to winter weather.
  
  Wednesday, January 28: Lecture 3: Orbital basics, seasons, parallax, Kepler's laws.
  
  Friday, January 30: Lecture 4: Constellations, Kepler's laws.
  Friday, January 30: Lecture Notes: Kepler's 2nd law and aphelion and perihelion.
  
  Problem Set #2 is due Friday, February 6 by 9:00 AM on ExpertTA.
  
  
  
• Week 2: 2/2-6                  Basic Physics II: Newton and Gravity [Ch. 3]
  Monday, February 2: Lecture 5: Galileo, gravity, Galilean relativity, and Newton's laws.
  Monday, February 2: Lecture Notes: Orbital speed vs orbital radius.
  Monday, February 2: Participation Exercise: Kepler's orbits and orbital capture.
  
  Wednesday, February 4: Lecture 6: Galilean relativity, Newton's laws, momentum and energy, gravity by Newton.
  Wednesday, February 4: Lecture Notes: Conservation of momentum, rifle recoil.
  
  Friday, February 6: Lecture 7: Newton's laws, circular motion, center of mass, angular momentum.
  Friday, February 6: Lecture Notes: Acceleration due to Earth's gravity.
  
  Problem Set #3 part 1 is due Friday, February 13 by 9:00 AM on ExpertTA.
  Problem Set #3 part 2 is due Friday, February 13 in class.
  
  
  
• Week 3: 2/10-14                  Basic Physics III: Light and Matter [Ch. 5, 16.1-2]
  Monday, February 9: Lecture 8: Potential energy, escape velocity, tidal forces, electromagnetic waves.
  Monday, February 9: Lecture Notes: Newton's version of Kepler's 3rd law for mass determination.
  
  Wednesday, February 11: Lecture 9: Electromagnetic spectrum, blackbody radiation, light pressure.
  Wednesday, February 11: Lecture Notes: Blackbody radiation of a hot star.