Chapter 6 Our Solar System and Its Origin
How was the Solar System Formed?
A viable theory for the formation of the solar system must be
based on physical principles (conservation of energy, momentum, the law of gravity, the law of motions, etc.),
able to explain all (at least most) the observable facts with reasonable accuracy, and
able to explain other planetary systems.
How do we go about finding the answers?
Observe: looking for clues
Guess: come up with some explanations
Test it: see if our guess explains everything (or most of it)
Try again: if it doesn’t quite work, go back to step 2.
Sun, a star, at the center…
Inner Planets (Mercury, Venus, Earth, Mars) ~ 1 AU
They are all rocky planets…
Asteroid Belt, ~ 3 AU
Outer Planets (Jupiter, Saturn, Neptune, Uranus), ~ 5-40 AU
They are all gaseous planets
Pluto: odd ball planet, more like a comet…
Keiper Belt ~ 30 to 50 AU
Oort Cloud ~ 50,000 AU
Where comets come from…
Cool link about solar system:
All the planets orbit the Sun in the same direction
The rotation axes of most of the planets and the Sun are roughly aligned with the rotation axes of their orbits.
Orientation of Venus, Uranus, and Pluto’s spin axes are not similar to that of the Sun and other planets.
GOTO e-textbook, Chapter 6, Section 2….
Read the brief descriptions of the solar system objects…
They are all…
rocky and small!
No or few moons
They are all…
gaseous and BIG!
Terrestrial and Jovian Planets
The Kuiper Belt and the Oort Cloud
A large body of small objects orbiting (the short period comets) the Sun in a radial zone extending outward from the orbit of Neptune (30 AU) to about 50 AU. Pluto maybe the biggest of the Kuiper Belt object.