Contents -- Other Galaxies and Active Galaxies

• Introduction
• Other Galaxies
  • Types of Galaxies
    1. Ellipticals
    2. Spirals
    3. Irregulars
  • Positions On Our Sky
    1. Review Questions
  • Distances to Galaxies
  • Hubble Law
  • Masses of Galaxies
  • Clusters of Galaxies
  • Superclusters
  • Galaxy Origins
    1. Galaxy Collisions and Mergers
  • Review Questions
• Active Galaxies
  • Quasars
  • Active Galaxies
  • Power Source for Active Galaxies and Quasars
  • The Short Life of an Active Galaxy
  • Review Questions
• Steps to the Hubble Constant Distance scale ladder
  • Rung 1 The Astronomical Unit
  • Rung 2 Geometric Methods
  • Rung 3 Main Sequence Fitting and Spectroscopic Parallax
  • Rung 4 Period-Luminosity Relation for Variable Stars
  • Rung 5a Galaxy Luminosity vs. Another Bright Feature
  • Rung 5b Luminosity or Size of Bright Feature
  • Rung 6 Galaxy Luminosity and Inverse Square Law
  • Rung 7 Hubble Law
  • Review Questions