Astronomy

Astronomy is the natural science dedicated to the study of all celestial objects and phenomena that originate outside of Earth's atmosphere, including stars, planets, galaxies, and the cosmic microwave background. As a discipline fundamentally rooted in physics, it applies principles such as gravity, thermodynamics, and electromagnetism to understand the formation, evolution, and physical nature of these cosmic entities. By bridging observational data with theoretical models, astronomy works in concert with astrophysics to explain the physical processes governing the universe and with cosmology to investigate the origin, large-scale structure, and ultimate fate of the cosmos itself.

1. Foundations of Astronomy
   1. History of Astronomy
      1. Ancient Astronomy
         1. Early Human Observations
            1. Naked-Eye Astronomy
            2. Seasonal Patterns
            3. Navigation by Stars
         2. Babylonian Astronomy
            1. Zodiac Development
            2. Lunar Calendars
            3. Solar Calendars
            4. Planetary Motion Records
            5. Eclipse Predictions
         3. Egyptian Astronomy
            1. Solar Calendar Development
            2. Astronomical Alignments in Architecture
            3. Decans and Star Clocks
            4. Heliacal Rising of Sirius
         4. Greek Astronomy
            1. Philosophical Approaches to the Cosmos
            2. Geocentric Models
               1. Aristotelian Cosmology
               2. Ptolemaic System
               3. Epicycles and Deferents
            3. Early Heliocentric Ideas
               1. Aristarchus of Samos
            4. Measuring the Earth and Cosmos
               1. Eratosthenes' Method
               2. Hipparchus and Star Catalogs
               3. Distance to Moon and Sun
         5. Chinese Astronomy
            1. Star Maps and Catalogs
            2. Supernova Records
            3. Lunar Mansions
            4. Armillary Spheres
         6. Islamic Astronomy
            1. Preservation of Greek Knowledge
            2. Astrolabe Development
            3. Star Names and Catalogs
            4. Observatories
         7. Mayan and Mesoamerican Astronomy
            1. Calendar Systems
            2. Venus Cycles
            3. Observatories and Alignments
            4. Eclipse Predictions
      2. The Scientific Revolution
         1. Nicolaus Copernicus
            1. Heliocentric Model
            2. De Revolutionibus Orbium Coelestium
            3. Retrograde Motion Explanation
         2. Tycho Brahe
            1. Precise Observational Techniques
            2. Tychonic System
            3. Supernova of 1572
            4. Uraniborg Observatory
         3. Johannes Kepler
            1. Laws of Planetary Motion
               1. First Law (Elliptical Orbits)
               2. Second Law (Equal Areas)
               3. Third Law (Harmonic Law)
            2. Analysis of Tycho's Data
            3. Rudolphine Tables
         4. Galileo Galilei
            1. Telescopic Observations
            2. Moons of Jupiter
            3. Phases of Venus
            4. Lunar Surface Features
            5. Sunspots
            6. Conflict with the Church
      3. Newtonian Era
         1. Isaac Newton
            1. Law of Universal Gravitation
            2. Three Laws of Motion
            3. Principia Mathematica
            4. Explanation of Kepler's Laws
         2. Development of Reflecting Telescopes
            1. Newtonian Reflector
            2. Advantages over Refractors
         3. Advances in Celestial Mechanics
            1. Orbital Predictions
            2. Comet Orbits
            3. Tidal Theory
      4. Modern Astronomy
         1. Spectroscopy Revolution
            1. Discovery of Spectral Lines
            2. Chemical Composition of Stars
            3. Stellar Classification
            4. Doppler Effect Applications
         2. Einstein's Theories of Relativity
            1. Special Relativity
            2. General Relativity
            3. Gravitational Lensing
            4. Tests of General Relativity
         3. The Great Debate
            1. Scale of the Universe
            2. Nature of Spiral Nebulae
            3. Shapley-Curtis Debate
         4. Hubble's Discoveries
            1. Cepheid Variables
            2. Distance Measurements
            3. Expanding Universe
            4. Hubble's Law
         5. Space Age Astronomy
            1. Launch of Sputnik
            2. Space-Based Observatories
            3. Planetary Exploration
   2. Fundamental Concepts
      1. The Celestial Sphere
         1. Concept and Purpose
         2. Celestial Poles
         3. Celestial Equator
         4. Zenith and Nadir
         5. Horizon
         6. Meridian
         7. Celestial Coordinates
            1. Declination
            2. Right Ascension
         8. Ecliptic
         9. Constellations
            1. Historical Development
            2. Modern Constellation Boundaries
            3. Star Names and Designations
      2. Coordinate Systems
         1. Horizontal System
            1. Altitude
            2. Azimuth
            3. Local Applications
         2. Equatorial System
            1. Right Ascension
            2. Declination
            3. Epoch and Precession
         3. Ecliptic System
            1. Ecliptic Longitude
            2. Ecliptic Latitude
         4. Galactic System
            1. Galactic Longitude
            2. Galactic Latitude
      3. Time and Celestial Motion
         1. Types of Days
            1. Sidereal Day
            2. Solar Day
            3. Apparent Solar Time
            4. Mean Solar Time
         2. Earth's Motions
            1. Rotation
            2. Revolution
            3. Precession
            4. Nutation
         3. Seasons
            1. Earth's Axial Tilt
            2. Solstices
            3. Equinoxes
            4. Seasonal Changes
         4. Calendar Systems
            1. Julian Calendar
            2. Gregorian Calendar
            3. Lunar Calendars
      4. Celestial Mechanics
         1. Kepler's Laws of Planetary Motion
            1. Mathematical Formulations
         2. Newton's Laws
            1. First Law (Inertia)
            2. Second Law (Force and Acceleration)
            3. Third Law (Action-Reaction)
         3. Gravitational Theory
            1. Universal Gravitation
            2. Gravitational Field
            3. Escape Velocity
         4. Orbital Mechanics
            1. Types of Orbits
            2. Orbital Elements
            3. Perturbations
            4. Resonances
         5. Tidal Forces
            1. Mechanism of Tides
            2. Earth's Tides
            3. Tidal Locking
            4. Roche Limit