1. The Universe And Its Stars
1.1. The Big Bang 13.7- Formed Billion Years Ago. Indicators:
1.1.1. Observable Galaxies Receding From Ours
1.1.2. Matter Made of Hydrogen and Helium
1.1.3. Measured Composition of Stars and Non-stellar Gases
1.1.4. Measurable radiation from stars' lights
2. Earth and The Solar System
2.1. The Milky Way Galaxy
2.2. Planets
2.2.1. Predictable patterns of movement
2.2.1.1. Gravitational Forces/ Patterns of Movement- Orbital Paths
2.2.1.2. Kepler’s laws describe common features of the motions of orbiting objects
2.2.2. Held In Place by The Gravitational Pull of The Sun
2.3. Solar System: formed from a disk of dust and gas, drawn together by gravity
2.3.1. Sun
2.3.1.1. One of 200 Billion Stars in The Milky Way Galaxy. Life Span of !0 Billion Years
2.3.1.1.1. Gravitational Forces
2.4. Planet Earth
2.4.1. Orbits The Sun
2.4.2. Has a Moon (Orbits the Earth)
2.4.2.1. Gravitational Forces- Tides on Earth
2.4.2.2. Monthly Orbit -Moon Phases as Visible from Earth
2.4.3. Axis of Rotation
2.4.3.1. Distribution of Sunlight
2.4.3.1.1. Reason for Seasons
2.4.3.1.2. Cycles of Change/ Climate Change
3. The History Of The Planet Earth
3.1. Historical Events
3.2. Extinction Level Events
3.2.1. Earthquakes, Volcanos, Ice Age
3.3. Changes in Rocks Formations
3.3.1. Rock Layers
3.3.1.1. Radioactive elements
3.3.1.2. Fossils Record
3.3.1.3. Tectonic Forces
3.3.1.4. Erosion