Class 15, 2/24/05

* 4:40-5:30pm: Quiz 2.

* 5:35-6pm: We will finish discussions on this week's materials, and hand back graded HW7 and solutions.
    ** Parallax
    ** Kepler's 3rd law (made more precise by Newton's law s):
    ** H-R diagram of stars: Main sequences, giants, white dwarfs, blackholes
            *** star radii
            *** etc.
    ** Cepheid variables (The North Star, Polaris, is one.): important for determining star distances.