Notes on Universe, Solar System, and Earth Systems

Universe and Solar System

• Key terms: Universe, Cosmos, Cosmology

• What is the Universe?

  • Contains all galaxies, stars, planets.

• Theories on the origin of the Universe:

  • 1) Big Bang Theory: universe started from a singularity that exploded.

  • Proponents: Georges Lemaître (first proponent); supported by Edwin Hubble, Arno Penzias, Robert Wilson.

  • 2) Steady State Theory: universe always existed and will always exist.

  • Proponents: Hermann Bondi, Thomas Gold, Fred Hoyle.

  • 3) Oscillating Universe Theory: universe expands and then contracts after energy is used up.

  • Proponent: Richard Tolman.

• What is a Big Crunch?

  • The universe stops expanding and collapses into itself, potentially forming a black hole.

• Activity-oriented notes:

  • Activity 1: Role-play on how the Universe is formed.

  • Activity 2: Concept map illustrating a chosen origin theory.

• Objective recap: Understand different hypotheses for the origin of the Universe.

The Solar System

• What is the Solar System?

  • Composed of the Sun, planets and their satellites, comets, and asteroids.

• Theories on the origin of the Solar System:

  • 1) Nebular Theory: originated from a nebula disrupted by a nearby event.

  • Proponents: Emmanuel Swedenborg, Immanuel Kant, Pierre-Simon Laplace.

  • 2) Encounter Theory: near collision between a passing star and the Sun.

  • Proponents: Leclerc and Georges Comte de Buffon.

  • 3) Protoplanet Theory: a modified nebular hypothesis; nebula disrupted to form protoplanets.

  • Proponents: Carl von Weizsäcker, Gerard Kuiper.

• Planet classification:

  • Terrestrial planets: MERCURY, VENUS, EARTH, MARS

  • Jovian (gas) planets: JUPITER, SATURN, URANUS, NEPTUNE

• Activity 3: Consider which theory you believe best for the Solar System’s origin.

• Titan’s methane, Mars rovers, and Pluto’s status as a planet/dwarf planet are discussed in later slides.

Earth: The Living Planet

• Objective: Describe Earth’s characteristics that support life.

• Key attributes:

  • Atmosphere

  • Soil and Vegetation

  • Hydrosphere

• Earth details:

  • Also known as the world; third planet from the Sun; the only known object in the Universe to harbor life.

• What makes Earth capable of supporting life?

  • 1) Atmosphere

  • 2) Soil and Vegetation

  • 3) Hydrosphere

• Atmosphere (major components):

  • $N_2 \,\approx\, 78.1\%$ by volume

  • $O_2 \,\approx\, 20.9\%$ by volume

  • $Ar \,\approx\, 0.9\%$ by volume

  • Trace gases: $CO<em>2 \approx 350\ \text{ppm}$; water vapor varies (0–4\%); $O</em>3 \approx 4\text{–}65\ \text{ppb}$; $CH<em>4 \approx 1{,}750\ \text{ppb}$; $N</em>2O \approx 280\ \text{ppb}$

• Soil and Vegetation: soil acts as a living medium for plant growth.

• Hydrosphere: all Earth’s water forms; reservoir, life support, heat reservoir, transport medium.

Earth: Four Subsystems

• Four subsystems: Atmosphere, Geosphere, Hydrosphere, Biosphere

• Atmosphere details:

  • Layers from surface upward: Troposphere (to ~$14.5\ \text{km}$), Stratosphere (to ~$50\ \text{km}$), Mesosphere (~$85\ \text{km}$), Thermosphere (~$600\ \text{km}$), Exosphere (to ~$10{,}000\ \text{km}$)

• Geosphere:

  • Includes all soil, rocks, minerals from crust to core

  • Three main layers: crust, mantle, core

• Crust:

  • Outermost layer; oceanic crust and continental crust

• Mantle:

  • Lies beneath crust; mainly silicate rocks rich in Mg and Fe; thickness ~$2900\ \text{km}$

• Core:

  • Radius ~$3400\ \text{km}$; innermost layer is solid inner core; outer core is liquid

• Hydrosphere:

  • All Earth’s water; ~$97.5\%$ saltwater; ~$2.5\%$ freshwater

• Biosphere:

  • All living things

• Interactions:

  • Matter and energy cycle between subsystems

• Explore prompt (NASA-style): consider requirements to replicate Earth’s system on another planet

Advances in Solar System Knowledge

• Pluto as a dwarf planet due to Kuiper Belt object status and orbital clearing tests

• 2005: Eris discovered; initially competed as a ninth planet

• Dwarf planets include: $ext{Ceres}, ext{Makemake}, ext{Haumea}$

• Planet X: speculation of a ninth planet due to Kuiper Belt object clustering

• Mars exploration:

  • Mars Rovers since the 1970s; study lithosphere and habitability

  • Mars One program aims to land humans on Mars by ~$2027$

• Titan: liquid methane observed on its surface

• Explore prompts discuss future discoveries

Assignment, Contributors, and NASA

• Assignment themes: short research on new discoveries and scientists who contributed to Earth system understanding

• Earth System Science (ESS): study of Earth as a system; interactions among atmosphere, geosphere, hydrosphere, and biosphere

• Key contributors:

  • James Hutton: father of modern geology; uniformitarianism

  • Alexander von Humboldt: holistic Earth observations

  • Vladimir Vernadsky: geochemistry; concept of noosphere

  • James Lovelock and Lynn Margulis: Gaia hypothesis (Earth as a self-regulating system)

• NASA focus: study components, linkages, dependencies, and fluxes within the Earth system

Internal Structure of the Earth

• Four main topic areas: the Earth’s internal structure and layers

• The Earth’s four main divisions (structural):

  • Crust

  • Mantle

  • Outer core

  • Inner core

• Crust details:

  • Outer layer; two types: oceanic and continental crust

• Mantle details:

  • Located below crust; consists of magma; includes mantle convection processes and tectonic forces such as ridge push and slab pull

• Core details:

  • Center of Earth; outer core is liquid; inner core is solid; generates Earth's magnetic field

• Lithosphere and asthenosphere:

  • Lithosphere = crust + upper mantle; rigid

  • Asthenosphere = partially molten layer beneath lithosphere; supports plate tectonics

• Magnetic vs geographic poles: magnetic north/south are generated by the liquid outer core

Final prompts and study tips

• Review major origin theories for the Universe and Solar System

• Be able to distinguish terrestrial vs Jovian planets

• Remember Earth’s four subsystems and their key components

• Understand the internal structure of the Earth and the role of the core in magnetism

• Be aware of current topics like dwarf planets, planetary formation theories, and NASA’s Earth-system focus

Quick recall cheat sheet

• Universe origin theories: Big Bang, Steady State, Oscillating; Big Crunch is a possible collapse scenario

• Solar System origins: Nebular Theory, Encounter Theory, Protoplanet Theory

• Earth subsystems: Atmosphere, Geosphere, Hydrosphere, Biosphere

• Atmospheric layers (bottom to top): Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere

• Core radii and layers: Outer core (liquid), Inner core (solid); core radius ~$3400\ \text{km}$

• Major atmospheric components: $N<em>2\approx 78.1\%$, $O</em>2\approx 20.9\%$, $Ar\approx 0.9\%$; CO₂ ~$350\ \text{ppm}$; CH₄ ~$1{,}750\ \text{ppb}$; N₂O ~$280\ \text{ppb}$

• Hydrosphere composition: 97.5% saltwater, 2.5% freshwater