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:

   • Tne Huygens probe.
   • Titan has an atmosphere.
   • Giant
     geysers
     on Enceladus.

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.