Plate Tectonics Overview

Plate Tectonics

• Plate tectonics is a theory that explains Earth's surface changes over time.
• Plates move on the mantle due to convection currents from the core.
• Technological advancements confirm plate movement rates (cm/year).

Types of Plate Boundaries

• Convergent boundaries: Plates collide, causing subduction (one plate sinks) or collision (both plates rise).
  • Oceanic plates sink beneath continental plates due to density.
  • Convergent boundaries create volcanoes, trenches, islands, and mountains (e.g., Himalayas).
• Divergent boundaries: Plates move apart, creating new crust and landforms like mountain ranges or rift valleys (e.g., Mid-Atlantic Ridge).
• Transform boundaries: Plates slide past each other, forming fault lines and causing frequent earthquakes (e.g., San Andreas Fault).

Landforms

• A landform is any naturally occurring physical feature of Earth's terrain.
• Geomorphologists study landform evolution (internal processes like tectonics and eruptions, external processes like erosion and weathering).
• Common landform types include coast, islands, peninsula, bay, mountain, hill, plateau, valley, canyon, and plains.
• Ocean basins have similar types (e.g., abyssal plains, seamounts).

Solar System, Galaxies, and the Universe

• The Solar System includes the Sun, planets, moons, asteroids, dwarf planets, Kuiper Belt objects, meteoroids, comets, and dust.
• Jupiter is the largest planet in our solar system.
• A galaxy is a massive collection of gas, dust, stars, and solar systems held by gravity.
• The Universe is all matter, energy, space, time, and its contents, including planets, stars, and galaxies. Dark matter composes a significant portion of the universe.

Celestial Bodies

• Planet: Spherical object orbiting the sun, with sufficient gravity to clear its orbit.
• Moon: Spherical object orbiting a planet.
• Asteroid: Rocky or metallic object orbiting the sun.
• Comet: Icy object orbiting the sun; develops a gas tail near the sun.
• Meteoroid: Small object in space.
• Meteor: Meteoroid entering Earth's atmosphere.
• Meteorite: Meteor that reaches the Earth's surface.
• Two types of planets: Terrestrial (solid surface, smaller, metal core) and Jovian (gas giants, no solid surface).

Stars

• Stars form in stellar nebulas from hydrogen gas.
• Protostars are the initial stage, aiming for nuclear fusion.
• Brown dwarfs are formed when fusion fails; stars are born from successful fusion.
• Stars spend most of their life in the main sequence, burning hydrogen, lasting 10 million to 1 trillion years based on mass.
• Low-mass stars become red giants before planetary nebulae.
• High-mass stars become red supergiants, and undergo supernovas, leaving behind neutron stars or black holes.

Constellations and Star Clusters

• A constellation is a group of stars seemingly close together in the sky. (Examples: Cancer, Leo, Orion, Draco).
• A star cluster is a group of stars physically close and gravitationally bound.

Sun

• The Sun is a middle-aged, medium-sized star at the center of our solar system.
• It's a ball of plasma (ionized gas).
• The Sun's layers (from inner to outer): Core (fusion, hottest), Radiative Zone (photon movement), Convection Zone (heat transfer), Photosphere (visible surface), Chromosphere (atmosphere), Corona (outermost, millions of km wide).
• Sun's temperature varies significantly by layer.
• Sunspots are caused by magnetic field changes in the convection zone.
• The Sun is 93 million miles from Earth, allowing liquid water and life.