Topic 12: Formation of Planetary Systems

• What is the primary component of the material that formed our Solar System?


  Hydrogen (75%)
• What percentage of the material in the Solar System is helium?


  23%
• What is a protoplanetary disk?


  A disk of gas and dust surrounding a newborn star where planets form
• What happens to the original material of the Solar System due to Solar Wind?


  A lot of it was blown away by the Solar Wind of our Star
• How does temperature vary in the protoplanetary disk?


  The temperature diminishes as the distance from the Sun increases
• What is the frost line in the context of the Solar System?


  A boundary at about 5 A.U. where volatile compounds freeze into particles of dust
• What types of planets form within the frost line?


  Small, rocky planets
• What types of planets form beyond the frost line?


  Giant, gaseous planets
• What materials could condense into solid grains within the frost line?


  Only metals and rock
• What happens to the cores of planets beyond the frost line?


  Their cores are icy and more massive, allowing them to gather hydrogen and helium gas
• How many protoplanets were estimated to exist in the early solar system?


  Between 50-100 protoplanets
• What evidence indicates the early solar system was chaotic?


  Many planets, moons, and asteroids are full of craters from collisions
• What is the axial tilt of Uranus?


  Almost 100°
• Why does Mercury have no atmosphere?


  Due to its high temperature and low mass
• Why does Venus have a thick atmosphere?


  Due to its high mass and temperature
• What determines if an object will have a spherical shape?

  Its mass
• What is the diameter threshold for icy moons to have irregular shapes?


  Less than 400 km
• What is the diameter threshold for rocky moons to have irregular shapes?


  About 600 km
• What is the Roche Limit?


  The smallest distance a large satellite can approach its parent body without being torn apart
• How do tidal forces affect a moon's shape?


  They can cause physical distortion, making the moon irregularly shaped
• What is tidal heating?


  The warming of a moon's interior due to gravitational pull slowing its rotation
• What is the result of tidal heating on Io?


  It remains geologically active with several active volcanoes
• What is the significance of the orbital resonance of Jupiter's moons?


  It enhances tidal heating due to frequent alignments with Jupiter
• What is the distance from the Earth to the Moon?


  380,000 km
• What are Lagrange Points?


  Specific locations where the combined gravity of two bodies equals the centripetal force needed for orbit
• Which Lagrange Points are stable?


  Points L4 and L5
• What is a prime example of Lagrange Points?


  The Trojan Asteroids of Jupiter
• What are the main factors that determine if an object will have an atmosphere?


  • Temperature: High temperature allows gas molecules to escape.
  • Mass: High mass provides stronger gravity to retain gas molecules.
• What are the effects of tidal forces on moons?

  • Tidal forces can distort the shape of moons.
  • They can cause tidal heating, affecting geological activity.
  • If too strong, they can shatter moons.
• What are the characteristics of captured moons?


  • Unusually tilted orbits and spins.
  • Irregular shapes.
  • Often originate from the Asteroid Belt or Oort Cloud/Kiuper Belt.
• What are the stages of planet formation in the early solar system?

  1. Formation of a protoplanetary disk.
  2. Accretion of small grains into cores.
  3. Formation of rocky and gaseous planets.
  4. Collisions and re-formations of protoplanets.