Exoplanets

Exoplanets, or extrasolar planets, are planets that orbit stars other than our Sun, forming the central focus of a major subfield within astrophysics. The study of these distant worlds relies heavily on principles of physics, utilizing detection methods such as the transit technique (measuring the dimming of starlight as a planet passes in front) and the radial velocity method (measuring the gravitational "wobble" a planet induces on its star). By analyzing the properties of thousands of discovered exoplanets—from massive "hot Jupiters" orbiting perilously close to their stars to rocky, Earth-sized worlds in habitable zones—scientists test theories of planet formation, stellar system architecture, and atmospheric dynamics. The sheer abundance and diversity of these planets have profound cosmological implications, suggesting that planetary systems are a common feature of the universe and fundamentally reshaping the scientific search for life beyond Earth.

1. Introduction to Exoplanetary Science
   1. Definition and Scope of Exoplanetary Science
      1. What Constitutes an Exoplanet
      2. Distinction from Solar System Planets
      3. Boundary Cases and Definitions
         1. Free-Floating Planets
         2. Brown Dwarf Companions
         3. Circumbinary Planets
   2. Historical Development
      1. Early Philosophical and Theoretical Foundations
         1. Ancient Speculation on Other Worlds
         2. Medieval and Renaissance Perspectives
         3. Enlightenment Era Scientific Speculation
      2. Theoretical Predictions and Early Searches
         1. 19th and Early 20th Century Attempts
         2. False Discoveries and Lessons Learned
      3. First Confirmed Discoveries
         1. Pulsar Planets Discovery
            1. PSR B1257+12 System
            2. Discovery Timeline and Methods
            3. Significance for the Field
            4. Unusual Nature of Pulsar Environments
         2. First Main Sequence Star Planet
            1. 51 Pegasi b Discovery
            2. Revolutionary Impact on Astronomy
            3. Challenges to Formation Theories
      4. Rapid Growth of the Field
         1. Discovery Rate Acceleration Post-1995
         2. Role of Technological Advances
         3. Major Survey Programs
   3. Fundamental Physics Principles
      1. Gravitational Dynamics
         1. Newton's Law of Universal Gravitation
         2. Kepler's Laws of Planetary Motion
            1. First Law: Elliptical Orbits
            2. Second Law: Equal Areas in Equal Times
            3. Third Law: Period-Distance Relationship
         3. Two-Body and Multi-Body Problems
         4. Orbital Elements and Coordinate Systems
      2. Electromagnetic Radiation and Spectroscopy
         1. Nature of Light and Electromagnetic Spectrum
         2. Doppler Effect
            1. Redshift and Blueshift Phenomena
            2. Application to Stellar Motion Detection
         3. Spectroscopic Principles
            1. Absorption and Emission Line Formation
            2. Spectral Resolution and Precision
            3. Stellar and Planetary Atmospheric Analysis
      3. Thermal Physics and Stellar Properties
         1. Blackbody Radiation Theory
         2. Wien's Displacement Law
         3. Stefan-Boltzmann Law
         4. Stellar Classification and Spectra
         5. Stellar Structure and Evolution Basics