NOTES: The Solar System:

Origin: the nebular theory fits most of the facts.The nebular theory:1. The Big Bang produced lumpy clouds--COBE satellite.2. Recycled star stuff with heavier elements combined with H and He gas from Big Bang, and gravity pulled it together. There were two supernova in our region.3. The gas cloud collapsed to a spinning disk and a globe in the center. 4. It heated as it collapsed, the center hotter than outer regions: Helmholtz contraction or heating.5. The sun's magnetic field slowed its rotation by dragging on electrons.6. There were swirls formed to predate satellite systems.7. The inner regions were too hot to allow light gases to collect. This left heavier elements and produced terrestrial planets.8. The outer regions were cool enough to allow large amounts of H and He to collect into the Jovian Planets.9. Dust collected into planetesimals, planetesimals into protoplanets. Gravity smoothed the larger objects to spheres.10. All planets, the sun, and satellites rotated and revolved in the same direction (prograde). Some planets (Venus, Uranus and Pluto) rotate retrograde because of large collisions (Velikovsky).

Steps in how the solar nebula forms.

The Nebular Hypothesis

Conservation of Angular Momentum:Contraction increase in rotation,

shown in reverse above.

Hannes Alfven explainedwhy the sun seemed to rotateslower than conservation ofangular momentum wouldsuggest

If you spin underwaterwith your arms out,it slows you down.

The magnetic field in thesolar nebula disk is like thearms, the charged particlesin that disk are like the water.

The Solar Nebula heated as it collapsed, the center hotter than outer regions: Helmholtz contraction or heating.

Compressing a gas makes it hotter, asparticles move faster.

Gravitational potentialenergy betweendust particles and gasbecomes kinetic energy of motion or heat.

The inner regions were too hot to allow light gases to collect. This left heavier elements and produced terrestrial planets.

Planetesimals (rocks) formed out of the dust by gravity.

Planetesimalscondensed intoplanets, moons,and asteroids.

Protoplanet model by Pawel Artymowicz of Sweden

Prograde vs Retrograde Rotation:Only Venus, Uranus spin retrograde--opposite to earth.

Velikovsky in 1950’s suggested

Venus was hit by something big,

flipping her rotation.

He was labeled a ‘crackpot’.

Bode's Law: Planet Dist. in AU = (3x2n-1 + 4)/10, n = 1, 2, 3, ...

Planet Prediction Actual DistanceMercury 0.4 0.39Venus 0.7 0.72Earth 1.0 1.00Mars 1.6 1.52Ceres 2.8 2.8 (Largest in asteroid belt)Jupiter 5.2 5.20Saturn 10.0 9.54Uranus 19.6 19.18Neptune 38.8 30.06Pluto 77.2 39.44 (was Pluto an original?) No reasonable explanation why this works.Distances found by radar ranging--bouncing radio waves andtiming.

Radar Ranging: bounce radio waves off planetary body.Distance = speed of light x time

Mass:Found using Newton's version of Kepler's 3rd Law a3/P2 = kM.This gives mass of sun. Then, let M = the mass of a planet witha moon in orbit about it. Planets without moons have massesdetermined by orbiting spacecraft or deviations in trajectories(paths) of passing objects.

Planetology:Example--content of Atmospheres: depends on1. Volcanism, and origin of planet. 2. Surface temperature--a measure of average speed of atomsand molecules. 3. Surface gravity and escape velocity.