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 1. based on physical principles (conservation of

energy, momentum, the law of gravity, the law of motions, etc.),

2. able to explain all (at least most) the observable facts with reasonable accuracy, and

3. Able to explain other planetary systems.

Testing Our Theory against other solar systems1. Can we find protoplanetary disks?2. Can we find other solar system?3. Does our theory explain the other solar system?

How do we go about finding the answers?

1.Look for clues2.Come up with some

explanations3.See if our idea explains

everything (or most of it)4.Try again: if it doesn’t quite

work, go back to step 2.

Clues – What does the solar system look like? • 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

NASA Figure

Cool link about solar system: • http://liftoff.msfc.nasa.gov/academy/space/solarsystem/solarsystemjava.html

• 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 - The Orbits of the Planets

Clues - What do they look like?The Inner Planets

They are all…• rocky and

small!• No or few

moons• No rings

They are all…• gaseous and

BIG!• Rings• Many moons

Clues - The Jovian Planets

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 SystemsAs of this date, ___ planets have been discovered.

2 (1996)

4

6

31

61

96

117

121

161

209

271

332

374 (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:Gliese 581 c

• Largest diameter:TrES-4

• Smallest found:Gliese 436 c