Planetary Geology - Introductory lecture
- Solar System Formation.
Where do the various elements come from?
What do you want in a model for the formation of the
Solar System (i.e. what needs to be explained)?
Broad outline for the nebular hypothesis for the formation
of the Solar System.
- Formation of nebula (>1000 atoms/cm3) from diffuse
gas of previous nova(s).
- Nebula collapse -> rotating and contracting disk,
and heat production.
- Development of proto star, T-Tauri phase and associated
'wind'. t=100,000 yrs
- Coeval development of condensates in a particular spatial,
- Gases mostly swept from inner solar system.
- Accretionary development of planets. Significant until
3.6 billion years ago.
- Development of small nebular disks around larger planets
and creation of moons.
- Internal differentiation of the planets (ongoing).
Discussion questions for next time:
- Why do the inner and outer planets have different bulk
compositions, and describe what differences you might expect in bulk compositions
of the inner planets given the scenario for nebular formation of the planets
given in your text?
- What determines the bulk composition of the nebular gas
- Velikovsky in Worlds in Collision proposed that Venus
was an interloper, a comet that was captured into its present orbit (yielding
the earth some atmosphere and rather wild times on the way). How might
this idea be tested if the model for solar system evolution described in
your text is anywhere near correct? Put another way - is this idea consistent
or inconsistent with the model for solar system evolution given in your
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