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.