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The Solar System

Notes from a presentation by Christian Ready at Windycon 38 on Friday, November 11, 2011. I have added web links.

  1. The Sun. Contains 98% of the mass of the Solar System. Sunspots and Magnetic Fields

  2. Mercury: The Messenger mission. The Caloris Basin. Large impacts.. Compared to Earth, Mercury's core is disproportionately large. This suggest that the planet may once have been much larger and that what we see is what is left over after many violent impacts.

  3. Venus. Surface air pressure 90 atmospheres, mostly CO2. Surface Temperature about 480 °C (896 °F) because of a runaway Greenhouse effect. This is the worst-case scenario for the buildup of CO2 in the Earth's atmosphere, out there for everybody to see.

    Lightning. Rains H2SO4. Active volcanos.

  4. Mars: Some evidence for water flowing there now. Olympus Mons. Meridani Planum. Opportunity. Valles Marineris — with some cool views produced by 3-D mapping by radar.

  5. Asteroid belt: Vesta, currently being orbited by the Dawn spacecraft.

  6. Jupiter. Gas giant. No well defined surface. Contains 1% of the mass of the solar system, about equal to that of the other planets, dwarf planets, asteroid, comets, etc. all taken together. The sheer mass of Jupiter means that it takes many impacts by comets, e.g. Shoemaker-Levy that might otherwise come into the inner Solar System and endanger us. The Great Red Spot. Rings. Some of its many moons:

    • Ganymede.
    • Io: Huge tidal forces because it is so close to Jupiter. Hence lots of volcanic activity.
    • Europa: Water. Possibility of life there.

  7. Saturn: Rings. Aurorae. Moons:

  8. Uranus: Rings. Rotation and axial tilt. Moon Miranda:

    Scientists disagree about what processes are responsible for Miranda's features. One possibility is that the moon may have been smashed apart in some colossal collision, and the pieces then haphazardly reassembled. Another, perhaps more likely, scenario is that the coronae are sites of large rocky or metallic meteorite strikes which partially melted the icy subsurface and resulted in episodic periods of slushy water rising to Miranda's surface and refreezing.
  9. Neptune: Just finished its first orbit around the Sun since its discovery in 1846. Happy Birthday! Very dynamic atmosphere.

  10. The Pluto system. Ready is firmly in the Pluto-is-not-a-planet camp. [So am I]. One more reason for this is that the Moons of Pluto do not rotate around Pluto. Instead Pluto and its moons rotate around a common barycenter that is beyond the surface of Pluto. I.e. Pluto is simply the largest of a group of bodies revolving around the same point in empty space. There may be other, smaller, objects there, possibly enough to endanger the New Horizons mission. NASA may change the spacecraft's trajectory through the Pluto system to improve its chances of survival.

  11. Other Kuiper Belt objects.


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