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Revision Lecture

This lecture revisits the phenomena of ocean tides influenced by the Sun and Moon, examines the impact of these celestial bodies on other planets and moons, and delves into magnetic fields and their generation. It covers the age of the Solar System, chemical symbols of various gases, and the differences in temperature on different planets. Additionally, it explains the dynamics of planetary systems, impact craters, the greenhouse effect, tectonic activity on Earth, Venus, and Mars, and highlights significant space missions exploring these areas.

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Revision Lecture

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  1. Revision Lecture Monday 14, 2009

  2. Tides • Ocean tides on Earth • The effect of Sun and Moon • Tides on the Moon • Tides on Io • Tides on Mercury

  3. Magnetic fields • Generation • Aurorae (Earth, Jupiter, Saturn) • Induced magnetic field • Magnetic field of the Sun and the solar cycle.

  4. The age of the Solar System • 4.56 billion years • 4.56 x 109 years • 4.56 giga years (Gyr) • 4560 million years • Billion = 109 = giga • Difference between American and British use of “billion”

  5. Chemical Symbols • Methane CH4 • Ammonia NH3 • Oxygen and nitrogen molecules O2 and N2 • Carbon dioxide CO2 • Carbon monoxide CO • Sufur dioxide SO2 • Sulfuric acid H2SO4

  6. Their planets of choice: • CH4 – J. S. U. N. • NH3 – J. S. • O2 and N2 - Earth • CO2 – Venus, Mars • CO • SO2 - Venus • H2SO4 - Venus

  7. Temperatures • Celcius vs. Kelvin: Remember 0o C = 273 K or 0 K = -273o C • What solar system body has a surface T of 40 K? • What is the surface temperature of Venus? Does it vary from night to day? • What is the surface temperature of Mercury? Does it vary from night to day? Why the difference between Mercury and Venus?

  8. Resonances • The dynamics of a system with more than 2 bodies is complex and generates resonances. • The system tries to achieve the lowest energy = highest stability. • As everything orbits, some resonances are stable (Pluto-Neptune; Io, Europa and Ganymede). Others are not stable (cleared gaps in Saturn’s rings).

  9. Planetary densities • Determination: Mass/Volume • Volume = 4/3 pR3 • Mean density of Earth = 5515 kg/m3 • Density of rock ≈ 3000 kg/m3 • Density of water = 1000 kg/m3 = 1 gr/cm3 • What do you deduce of a planet hasmean density << 3000 kg/m3?

  10. Impacts and impact craters • What was the era of heavy bombardment? • Where are craters seen? • What do many craters mean? • What planets/areas of planets/moons have many craters? What have few?

  11. The Greenhouse effect • On Earth • On Venus • On Mars

  12. Tectonic activity • Earth: plate tectonic • Venus: “flake” tectonic • Mars: VallesMarineris. • Importance of crust thickness on type of tectonic activity. • Ganymede: fractures on both light and dark lands – tectonic activity.

  13. Internal heat • Evidence: • Recent tectonic activity seen on surface • Own magnetic field • Likelyhood: • larger bodies retain heat more readily – they cool more slowly – terrestrial planets activity as a function of mass. • Bodies which are tidally stressed can be kept warm (Io). • Strange examples: • Ganymede • Titan (reheating?) • Enceladus (tidal?)

  14. Liquid, solid or gas?

  15. Space Missions • Mercury: Mariner 10, Messenger • Venus: Venera, Magellan • Mars: Vikings 1-4, Pathfinder, Rovers … • Jupiter: Pioneers 10,11, Voyagers 1,2, Galileo • Saturn: Voyagers 1,2, Cassini • Uranus + Neptune: Voyagers 1,2 • Pluto: New Horizons

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