BH

1-2_Earth's birth questions_ - Tagged

Chapter 1: Cosmology

1. The New Definition of Planets

  • Overview of how classification of celestial objects has evolved over time in response to discovery and scientific advancements.

2. The Modern Universe

  • Description of the universe's structure and the nature of cosmic bodies within it.

3. The Solar System

Composition of the Solar System

  • One star: Sol (the Sun).

  • Four terrestrial planets: Mercury, Venus, Earth, Mars.

  • Four jovian planets: Jupiter, Saturn, Uranus, Neptune.

  • Numerous dwarf planets and small solar system bodies including:

    • Trans-Neptunian icy bodies (e.g., Pluto, "Xena" (2003 UB 313), Ceres).

    • Uncounted moons, comets, asteroids, and space debris.

4. The Birth of Earth

  • Significant geographic regions involved in Earth's historical context: Africa, Eurasia, and the Arabian Peninsula (NASA).

The Solar System

Terrestrial Planets

  • Location:

    • Inner solar system.

  • Characteristics:

    • Diameter: 4,879 - 12,756 km.

    • High density (4 - 5.5 g/cm³).

    • Composed of rocky shells and metallic cores.

Jovian Planets

  • Location:

    • Middle to outer solar system.

  • Characteristics:

    • Diameter: 49,528 - 148,984 km.

    • Low density (<1.0 g/cm³).

    • Composed of gas shells with small rock cores.

    • All possess rings and numerous moons.

Trans-Neptunian Objects

  • Location:

    • Outermost solar system.

  • Characteristics:

    • Elongated orbits (>200 years).

    • Inclined orbit planes.

    • Diameter: 1,000 - 2,300 km.

    • Comprised of ice with a rocky core.

    • Density: between terrestrial and jovian.

Ceres: A Dwarf Planet

  • Location:

    • Located among the asteroid belt between Mars and Jupiter.

  • Characteristics:

    • Very small: diameter 530 - 950 km.

    • Density: 2.10 - 3.44 g/cm³ (between terrestrial and jovian).

Questions

  • Classification of planets:

    • Earth, Venus, Mercury, Mars are terrestrial or jovial?

    • Jupiter, Saturn, Uranus, Neptune are terrestrial or jovial?

    • Gas giants (Jupiter, etc.) are much larger than inner planets - True or False?

The Rotating Earth Hypothesis

  • Jean Foucault's pendulum experiment established Earth's rotation:

    • An oscillating pendulum remains in the same plane, the frame rotates around it over time.

  • Relation to Newton’s 1st law of motion:

    • Objects in motion remain in motion, implying Earth rotates on its axis.

Evidence Supporting Earth's Spherical Shape

  • Observation of ships disappearing over the horizon progressively from base to top.

  • During lunar eclipses, Earth casts a curved shadow on the Moon.

  • Eratosthenes' measurements showed a 7-degree difference in shadows over ~550 miles.

Distance to Stars

  • 1838 discovery of the distance to Alpha Centauri:

    • Distance: 40.85 trillion km, equivalent to 4.3 light years.

Formation of Galaxies

  • Gravity pulls stars together to form galaxies.

  • Our galaxy: Milky Way.

The Expanding Universe

  • Hubble's observations (1929): all distant galaxies exhibit a red shift and are moving away.

  • Concept of the expanding universe likened to baking raisin bread.

The Big Bang Theory

  • Hypothesis explaining the universe's expansion from a central point of condensed energy and matter.

  • Explosion occurred approximately 10 - 20 billion years ago, with matter cooling to form nebulas after about 1 million years.

Star Formation

  • Protostars heat as hydrogen and helium compress, igniting nuclear fusion leading to star birth.

  • Supernovae can release heavier elements essential for galaxy formation.

Our Star - Sol

  • The Sun formed less than 5 billion years ago as a third or fourth generation star from a nebula.

  • Stellar wind dispersing light elements into the outer solar system.

What Makes Earth Unique?

  • Rich in water (>70%).

  • Diverse crust: contains rocks beyond basalt.

  • Active plate tectonics facilitating recycling of elements crucial for life.

Internal Structure of Earth

Formation and Differentiation

  • Internal layers: inner core, outer core, mantle, crust.

Chemical Composition Model

  • Layers differentiated based on material composition:

    • Crust, mantle, core (including Moho discontinuity).

Physical Property Model

  • Layers based on physical properties:

    • Lithosphere, asthenosphere, mesosphere, outer core.

Seismology and Earth's Interior

  • Method of studying Earth's interior by analyzing seismic waves:

    • Reflection and refraction provide insights into composition and changes in density.

Questions

  • What is the outermost layer of Earth?

  • What does geoscientists interpret the core to consist of?

  • The crust and uppermost mantle together form what?

  • True or false: lithosphere and asthenosphere are differentiated by composition.

  • True or false: the asthenosphere is the outermost layer.