Lecture Ch 06 [Compatibility Mode] Ast 201


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Lecture Ch 06 [Compatibility Mode] Ast 201

  1. 1. Chapter 6 The Solar System y
  2. 2. Units of Chapter 6 An Inventory of the Solar System Planetary Properties Computing Planetary Properties The Overall Layout of the Solar System Terrestrial and Jovian Planets Interplanetary Debris
  3. 3. Units of Chapter 6, cont. Spacecraft Exploration of the Solar System Gravitational “Slingshots” g How Did the Solar System Form? The C Th Concept of Angular Momentum t fA l M t
  4. 4. 6.1 An Inventory of the Solar System Early Earl astronomers kne Moon, stars, Merc r knew Moon stars Mercury, Venus, Mars, Jupiter, Saturn, comets, and meteors Now known: Solar system has 135 moons, one star, star nine planets (added Uranus Neptune and Uranus, Neptune, Pluto), asteroids, comets, and meteoroids
  5. 5. 6.2 Planetary Properties
  6. 6. 6.2 Planetary Properties • Distance from Sun known by Kepler’s laws • Orbital period can be observed • Radius known from angular size • Masses from Newton’s laws • Rotation period from observations • Density can be calculated knowing radius and mass
  7. 7. 6.4 Terrestrial and Jovian Planets Terrestrial planets: Mercury, Venus, Earth, Mars Jovian planets: Jupiter, Saturn, Uranus, Neptune Pluto is neither
  8. 8. 6.4 Terrestrial and Jovian Planets Differences between the terrestrial planets: • Atmospheres and surface conditions are very dissimilar di i il • Only Earth has oxygen in atmosphere and liquid water on surface • Earth and Mars rotate at about the same rate; Venus and Mercury are much slower and Venus rotates in the slower, opposite direction • Earth and Mars have moons; Mercury and Venus don’t • Earth and Mercury have magnetic fields; Venus and y g ; Mars don’t
  9. 9. 6.6 Spacecraft Exploration of the y Solar System Sojourner was deployed on Mars in 1997:
  10. 10. 6.7 How Did the Solar System Form? Nebular N b l contraction: i Cloud of gas and dust contracts due to gravity; conservation of angular momentum means it spins faster and faster as it contracts
  11. 11. 6.7 How Did the Solar System Form? Condensation theory: y Interstellar dust grains help cool cloud, and act as condensation nuclei
  12. 12. Summary of Chapter 6 • Solar system consists of Sun and everything orbiting it • Asteroids are rocky, and most orbit between orbits of Mars and Jupiter p • Comets are icy, and are believed to have formed early in the solar system s life system’s • Major planets orbit Sun in same sense, and all but Venus rotate in that sense as well • Planetary orbits lie almost in the same plane
  13. 13. Summary of Chapter 6, cont. • Four inner planets – terrestrial planets – are rocky, small, and dense y • Four outer planets – jovian planets – (omitting Pluto) are gaseous and large • Nebular theory of solar system formation: cloud of gas and dust gradually collapsed under its own gravity, spinning faster as it shrank •C d Condensation theory says dust grains acted as ti th d t i t d condensation nuclei, beginning formation of larger objects