Earth Science Study Guide

Part 1: Earth's Role in Space

Earth's Motion

• Rotation
  • Definition: Spinning or turning of Earth on its axis.
  • Causes day and night (24-hour duration).
• Revolution
  • Definition: Earth's orbit around the Sun in an oval path.
  • Duration: 365 days/1 year.
  • Causes change in direction of Earth's tilt, affecting global climate.
  • Stars shift in the night sky.
• Precession
  • Axis traces out a cone shape over 26,000 years.
• Nutation
  • Rocking, swaying of Earth's axis due to the moon's gravitational pull.
  • Wobbling takes about 18.6 years.

Seasons

• Reason for Seasons: Earth's tilted axis.

Kepler's Laws

1. Planets orbit the sun in an elliptical path.
2. Law of equal areas: Earth travels faster when closer to the sun.
3. Orbital period is proportional to the cube of the semi-major axis.

Barycenter

• Center of mass between two orbiting bodies.
• Earth's barycenter is slightly outside center of the sun.

Shape of Earth

• Oblate Spheroid: Slightly larger diameter at the equator than at the poles.

Hierarchy of the Universe

1. Earth
2. Solar System
3. Milky Way Galaxy
4. Universe (expanding)

Part 2: The Sun

• Energy Source: Fusion (Hydrogen + Hydrogen = Helium)
  • Releases heat and light.
  • Occurs in the sun.
• Electromagnetic Waves
  • Safe: Radio waves, infrared.
  • Dangerous: X-rays, UV rays, gamma rays.
• Protection
  • Ozone layer blocks UV radiation.
  • Magnetic field blocks cosmic rays and solar wind.

Photosynthesis

• Equation: Water + Carbon Dioxide + Sunlight → Oxygen + Sugar

The Moon and the Tides

• Phases of the Moon: Caused by moon's motion and reflected sunlight.
• Tides: Changes in ocean elevation due to gravitational pull of the moon and sun.
• Tidal Types
  • Spring Tide: Greatest tidal range.
  • Neap Tide: Lowest tidal range.
• Tidal Patterns
  • Semidiurnal: 2 High, 2 Low tides per day.
  • Diurnal: 1 High, 1 Low tide per day.

Part 3: Lithosphere

Definitions

• Lithosphere: Rigid layer including crust and upper mantle.
• Asthenosphere: Weak, flowing layer below lithosphere.

Plate Boundaries

• Divergent
  • Plates move apart.
  • No disaster, seafloor spreading occurs.
• Convergent
  • Plates move together.
  • Earthquakes, potential tsunamis.
• Transform Fault
  • Plates grind past each other.

Evidence for Plate Tectonics

1. Earthquakes at transform boundaries.
2. Paleomagnetism: Alternating magnetic strips at ocean ridges.

Rock Types

• Igneous: Crystallization of molten magma.
  • Found at volcanoes, ocean floors.
• Sedimentary: Compacted sediments.
• Metamorphic: Formed by heat/pressure.

Alfred Wegener's Hypothesis

• Continents once formed Pangaea.
• Evidence: Matching fossils, rock types.

Plate Tectonics Theory

• Lithosphere is broken into plates.
• Plates float on the asthenosphere.
• Driven by heat transfer (convection) in the asthenosphere.
• Hot magma rises, cold magma sinks.