ENCOUNTER THEORY

• Encounter theory


  Planets were formed from the material ejected from the sun during an encounter with another celestial object
• Encounter theory


  • Has several forms, including the planetesimal theory and the tidal theory
• Planetesimal theory


  Describes Earth starting from a solid mass smaller than its present size
• Tidal theory


  Proposes that the hot gas from the passing star condensed into planets instead of condensing into planetesimals
• Encounter theory


  • Proposes that the planets formed from the material ejected from the sun during an encounter with another celestial object
• According to the planetesimal theory, a passing star termed as intruding star nearly collided with the protosun. The massive gravitational pull of the intruding star causes the protosun to eject filaments of material. These materials condensed into planetesimals from which the planets were formed through accretion. Unlike the nebular theory which describes Earth starting from molten mass, the planetesimal theory describes Earth starting from a solid mass smaller than its present size. The oceans and the atmosphere were formed on Earth through volcanic activities.
• The encounter theory proposes that the planets were formed from the material ejected from the sun during an encounter with another celestial object. This celestial object could have been another star. The encounter theory has several forms, including the planetesimal theory and the tidal theory
• According to the encounter theory, the planets were formed from the material ejected from the Sun during an encounter with another celestial object. This celestial object could have been another star.
• Encounter theory


  Proposes that the planets were formed from the material ejected from the sun during an encounter with another celestial object
• Encounter theory


  • Could have been another star
  • Includes the planetesimal theory and the tidal theory
• The encounter theory proposes that the planets were formed from the material ejected from the sun during an encounter with another celestial object
• Planetesimal theory


  According to the planetesimal theory, a passing star termed as intruding star nearly collided with the protosun. The massive gravitational pull of the intruding star causes the protosun to eject filaments of material. These materials condensed into planetesimals from which the planets were formed through accretion.
• Oceans and atmosphere formation

  The oceans and the atmosphere were formed on Earth through volcanic activities.
• Planetesimal Theory


  Theory that planets and their moons were created by the accretion of minute solid particles rather than by gaseous or liquid material condensation
• Proponents of the Planetesimal Theory

  • Thomas Chrowder Chamberlin (American geologist)
  • Forest Ray Moulton (American astronomer)
• Planetesimal Theory proposed


  1905
• Chamberlin realized Earth was older


  Than what Kelvin proposed
• Planetesimal Theory


  1. Accretion of minute solid particles created planets and their moons

  2. Moulton provided mathematical calculations to support Chamberlin's idea
• Planetesimal Theory


  Theory that the solar system formed from the contraction of hot material from the sun
• The Planetesimal Theory is no longer accepted today
• Tidal Theory


  Theory that the solar system formed as a result of a near collision between a passing star and the sun
• The Tidal Theory proposes that the hot gas from the passing star condensed into planets instead of condensing into planetesimals
• When the star passed near the sun, the tidal forces pulled material from the sun, forming the planets
• Formation of planets in the solar system

  1. Gravitational attraction pulled mass of dust and gas from remaining nebula around the sun

  2. Gas particles condensed into liquid and solid states

  3. Particles clumped together to form cosmic bodies of different sizes

  4. Cosmic bodies further condensed into planets

  5. Interaction from gravity of passing star and sun led to formation of planets
• Positions of planets


  • Materials closer to the sun are denser, explaining positions of terrestrial planets
  • Materials from passing star are less dense, explaining positions of Jovian planets
• Planetesimal theory


  Proposes that hot gas from passing star condensed into planetesimals
• Tidal theory


  Proposes that hot gas from passing star condensed into planets
• The tidal theory was proposed by James Jeans and Harold Jeffreys in 1918
• Tidal theory


  Theory that the planets formed from the hot material ejected from the sun during an encounter with another celestial object
• One problem of the tidal theory is that the hot material from either star cannot contract, so planets will not form
• Encounter theory


  • Proposes that the planets formed from the material ejected from the sun during an encounter with another celestial object
  • Has several forms, including the planetesimal theory and the tidal theory
• Planetesimal theory


  Describes Earth starting from a solid mass smaller than its present size
• The planetesimal theory was proposed by American geologist Thomas Chrowder Chamberlin and American astronomer Forest Ray Moulton
• The planetesimal theory is no longer accepted today due to the fact that hot material from the sun will expand and dissipate rather than contract
• In the encounter theory, the planets were formed from the material ejected from the Sun during an encounter with another celestial object. This celestial object could have been another star.