Cosmic Origins and Earth’s Dynamic Processes: A Comprehensive Overview

Posted on Jan 7, 2025 in Geology

The Scientific Method

  1. Ask a question.
  2. Do background research.
  3. Construct a hypothesis.
  4. Test your hypothesis by doing an experiment.
  5. Analyze your data and draw a conclusion.
  6. Report results.

Geocentric Model

  • Earth is the center of the universe.
  • The universe consists of concentric spheres with Earth in the center.
  • Planets have their own sphere, but stars are all in one sphere.
  • All heavenly motion consists of perfect, uniform circular motion.
  • Ptolemy said that the planets didn’t rotate with circular orbits but with epicycles.
  • Epicycle: An orbit (small loop) within an orbit (planet around the Sun).

Heliocentric Model

  • The Sun is the center of the universe.
  • The Earth and all planets revolve around the Sun.
  • The Earth rotates.
  • The Moon orbits around the Earth.
  • The stars have a fixed location.

Planet Movement

Because the Earth’s orbit is closer to the Sun, one revolution of the Earth needs less time than one revolution of Mars. Therefore, we see the retrograde motion of Mars from the Earth.

Kepler’s Laws of Planetary Motion

  1. The orbits of the planets are elliptical, with the Sun at one focus of the ellipse.
  2. A line connecting the Sun and a planet sweeps out equal areas in equal time.
  3. The period of the orbit is related to the average separation.

The Big Bang Theory

The Big Bang was the expansion of the universe due to the large concentration of mass that existed in a very small space. This theory explains the origin of the universe.

The Big Rip Theory

The Big Rip is a theory about the end of the universe which claims that the universe will continually expand at an accelerated pace until it leads to everything getting ripped and torn apart.

The Big Crunch Theory

The Big Crunch is another theory about the end of the world, but it claims that the universe goes into a series of Big Bangs or Big Crunches over and over again.

Measuring Distances in Space

  1. The AU (Astronomical Unit) (150,000,000 km), which is the distance between the Earth and the Sun.
  2. The light-year (9.46 x 1012 km), which is the distance traveled by light in one year.

Star Stuff

“Star stuff” means that we come from the first atoms created during the Big Bang because, from that moment on, more complex atoms were created in stars, and when the stars die, they are expelled into space.

Looking Back in Time

Because light has a finite speed, the further out we look into the universe, the further back in time we see, as the light takes more time to arrive at the Earth. When we see a star, we see the light that was emitted a long time ago.

Earth’s Movement

  • Rotation: The Earth rotates around its axis, which takes 24 hours.
  • Revolution: The Earth revolves around the Sun, which takes 365 days and 6 hours.

Definitions

  • Planet: A moderately large object which orbits a star; it shines by reflected light.
  • Star: A large, glowing ball of gas that generates heat and light through nuclear fusion.

Tectonic Plates

  • The theory was first proposed by Alfred Wegener in 1910.
  • The continents were once all together, forming a supercontinent called Pangea.
  • The continents broke apart and drifted to their present locations.

Evidence for Continental Drift

  1. The shorelines of the continents fit together like the pieces of a puzzle.
  2. If areas A and B were once together, then we should find similar rock types in these two locations.
  3. If we could find the same fossils in areas A and B, fossils that exist nowhere else. (Correlating fossils)
  4. Seafloor spreading.
  5. Measurement by GPS.

Seafloor Spreading

Seafloor spreading is a theory that defends that if the continents are moving apart, the seas are getting wider.

Plate Boundaries

  • Convergent boundaries: Where plates move towards each other (e.g., Andes).
  • Divergent boundaries: Where plates move away from each other (e.g., Iceland).
  • Transform boundaries: Where the plates slide past each other (e.g., The San Andreas Fault).

Subduction Zones

A subduction zone is an area where two boundaries collide, and as a result, one of them sinks, originating volcanoes.

Volcanoes

Volcanoes usually occur where subducting slabs reach a depth of about 100 km.

Natural Events and Catastrophes

  • Natural event: A concrete climatic situation or event produced by nature.
  • Catastrophe: An extreme physical natural event that kills people or overwhelms local capacity for damage control or recovery.
  • Vulnerability: The degree to which a society is susceptible to harm on being exposed to a natural hazard.
  • Risk areas: Places on Earth’s surface that are dangerous for settlement or human life.

Reducing the Effects of Catastrophes

To reduce the effects of a catastrophe, we can make predictions of what is probable to happen and take action to avoid its effects (prevention).