The Solar System: Planets and Beyond

Posted on Feb 19, 2025 in Geology

The Solar System

The Earth is the center of the universe and turns around the sun, the moon. The sun is the center of the universe.

Characteristics of Planets

  • Its mass should be sufficient to give it a nearly spherical shape.
  • Must have cleared its orbit.

Composition of the Solar System

  • Sun: A sphere of glowing gases that releases energy through thermonuclear reactions in its core.
  • Planets: Celestial bodies orbiting the sun.
    • Inner Planets: (Mercury, Venus, Earth, Mars): Near the sun, small, rocky, and with a gaseous atmosphere.
    • Outer Planets: (Jupiter, Saturn, Uranus, Neptune): Far from the sun, big, not rocky, gaseous, and liquid.
    • Dwarf Planets: Celestial bodies orbiting the sun that meet the criteria.
    • Satellites: Celestial bodies that revolve around the planets. Mercury and Venus do not have any.
    • Asteroids: Rocky bodies smaller than planets with an irregular shape.
    • Comets: Small celestial bodies of ice and dust particles.

Solar System Characteristics

  • The sun and all planets revolve in the same direction.
  • The orbits of the planets are ellipses.
  • The orbits of the planets are located approximately in the same plane.
  • The inner planets are small and dense, the outer planets are large and lightweight.
  • Have impact craters.

Planetesimal Theory

  1. Nebula Initial: 4600 million years ago, a nebula of dust and gas began to contract.
  2. Gravitational Collapse: Mass formed a central mass and a rotating disc.
  3. Formation of Protosun: The collision of particles in the central mass released a large amount of heat, creating the protosun.
  4. Planetesimal Formation: Pooled dust particles resulting in larger bodies.
  5. Formation of Protoplanets: Collisions of planetesimals formed planets.
  6. Sweep of the Orbit

Evolutionary Theories

  • Fixism (Cuvier): The belief that species are immutable.
  • Lamark (Jean Baptiste): Living things have a natural tendency towards complexity and progress, necessarily changing.
  • Darwin: More individuals are born than can survive. There are variations among individuals, and natural selection occurs.
  • Synthetic Theory: The evolutionary unit is the population. The origin of variability is in mutations.

Related Species

  • Homo habilis: Africa 2.5 to 1.5 Ma ago, cranial capacity 600 cm³, manufactures tools on one side.
  • Homo ergaster: 1.8 and 1.2 Ma, capacity from 800 to 1000 cm³, manufactures tools on both sides.
  • Homo erectus: 1.7 Ma, 50,000 years ago, between 800 and 1100 cm³.
  • Homo antecessor: 1.2 Ma and 300,000 years ago, 1000 to 1100 cm³.
  • Homo neanderthalensis: 300,000 years to 28,000 years ago, 15,000 cm³.

Bipedalism

The standing is the criterion used to differentiate between hominids and apes. The position of the foramen magnum, the hip, and the foot are all indicators.

Labor

The adaptation to bipedalism involves a narrowing of the pelvis and the size of the head. This means that the offspring are more dependent on the mother for longer.

Speech

It has the mental capacity and the speech apparatus, two brain areas that are in the left hemisphere.