Chapter 19-3 Formation of the Solar System (Solar System Simulator: http://space.jpl.nasa.gov/ )
Successful models in science Must account for and make sense of observations
Do we Have a Viable Theory? • It 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. • Testing Our Theory against other solar systems • Can we find protoplanetary disks? • Can we find other solar system? • Does our theory explain the other solar system?
How do we go about finding the answers? • Look for clues • Come up with some explanations • See if our idea explains everything (or most of it) • Try again: if it doesn’t quite work, go back to step 2.
Clues – What does the solar system look like? NASA Figure • Sun, 0 AU • Inner Planets (Mercury, Venus, Earth, Mars) ~ 1 AU • Asteroid Belt, ~ 3 AU • Outer Planets (Jupiter, Saturn, Neptune, Uranus), ~ 5-40 AU • Kuiper Belt, ~ 30 to 50 AU • Oort Cloud, ~ 50,000 AU • Cool link about solar system: • http://liftoff.msfc.nasa.gov/academy/space/solarsystem/solarsystemjava.html
Clues - The Orbits of the Planets • All the planets orbit the Sun in the same direction • The spin 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.
Clues - What do they look like?The Inner Planets • They are all… • rocky and small! • No or few moons • No rings
Clues - The Jovian Planets • They are all… • gaseous and BIG! • Rings • Many moons
How did the solar system form? National Geographic’s Naked Science: “Birth of the Solar System” – sun, fusion, nucleosynthesis University of California: “Order from Chaos: The Birth of the Solar System”
Other Solar Systems As of this date, ___ planets have been discovered. 2 (1996) 4 6 31 61 96 117 121 161 209 271 332 (4/14/2010) 418 (4/27/2010)
“For then why may not every one of these Stars or Suns have as great a Retinue as our Sun, of planets, with their moons, to wait upon them? Nay, there’s Manifest reason why they should.” Physicist Christiaan Huygens, 1698 “There are countless suns and countless earths all rotating around their suns in exactly the same way as the seven planets of our system . . . The countless worlds in the universe are no worse and no less inhabited than our Earth.” Giordano Bruno, 1584; burned at the stake for heresy
Oldest known:PSR B1620-26c (13 billion years) • First Discovered:51 Pegasi b (1996) • Largest core:HD 149026 b • Most distant found:OGLE-2005-BLG-390Lb (21,500 light years) • May have liquid water:Gliese581 c • Largest diameter:TrES-4 • Smallest found:Gliese436 c