1. Understand the movement of planetary bodies.
Complex Knowledge: demonstrations of learning that go aboveand above and beyond what was explicitly taught.
Knowledge: meeting the learning goals and expectations.
Foundational knowledge: simpler procedures, isolated details, vocabulary.
Limited knowledge: know very little details but working toward a higher level.
Understand how our view of the solar system has changed over time and how discoveries made have led to our changing our view of the solar system.
Learn planetary characteristics such as number of moons, size, composition, type of atmosphere, gravity, temperature and surface features.
Understand the movement of planetary bodies.
Understand which planetary characteristics are more important than others when it relates to our understanding of other worlds.
Understand how proximity to the sun influences planets.
Understand the methods and tools scientists use to learn about other planets and moons in our solar system.
Understand the conditions needed for a habitable world and determine if there are habitable worlds in our solar system or outside the solar system.
Understand how we look for and study solar systems other than our own.

2. Formation of the Solar System

3. This Week’s questions: Are all planets created equal?
What events and materials were necessary to form our solar system?
How do planets differ from one another and why?

4. Any model of Solar System formation must explain the following facts:
All the orbits of the planets are prograde (i.e. if seen from above the North pole of the Sun they all revolve in a counter-clockwise direction).
All the planets have orbital planes that are inclined by less than 6 degrees with respect to each other (i.e. all in the same plane- ecliptic).
Terrestrial planets are dense, rocky and small, while Jovian planets are gaseous and large.

5. Lets get more specific Any model must explain that
Planets are relatively isolated in space
Planetary orbits are nearly circular
Planetary orbits all lie in (nearly) the same plane
Direction of orbital motion is the same as direction of Sun’s rotation
Direction of most planets’ rotation is also the same as the Sun’s

6. Modeling Planet Formation (cont.)
6. Most moons’ orbits are also in the same direction
7. Solar system is highly differentiated
8. Asteroids are very old, and not like either inner or outer planets
9. Kuiper belt, asteroid-sized icy bodies beyond the orbit of Neptune
10. Oort cloud is similar to Kuiper belt in composition, but farther out and with random orbits

7. Statistics of our Solar System
Sun contains 99.8% of the total mass of the solar system
74% hydrogen
24% helium
2% all other elements
Metals - 0.2%
Rocks - 0.4%
Ices – 1.4%
Light gases - 98%

8. Modeling Planet Formation
Solar system is evidently not a random assemblage, but has a single origin.
Planetary condensation theory, or Nebular Theory seems to work well.
Lots of room for variation; there are also irregularities (Uranus’s axial tilt, Venus’s retrograde rotation, etc.) that must be allowed for by the model.

9. Nebular Theory/Solar Nebular Disk Model
Nebular theory is the most widely accepted model explaining the formation of the Solar System.
First proposed with evidence by:
Emanuel Swedenborg, Immanuel Kant, and 
Pierre-Simon Laplace in 1734
Originally applied only to our own Solar System, this method of planetary system formation is now thought to be at work throughout the universe.
The widely accepted modern variant of the nebular theory is Solar Nebular Disk Model (SNDM) or simply Solar Nebular Model.

10. Steps to a Solar System….in..1, 2, 3ish steps

11. Step 1 –formation of a star
stars form in massive and dense clouds of molecular hydrogen—giant molecular clouds (GMC).
matter coalesces through gravity to create smaller denser clumps
Continue to collapse to form proto-stars that will eventually end up as
Brand new stars! 
sun-like stars usually take about 50 million years to form

13. Step 1 –formation of a star
star formation produces a gaseous proto-planetary disk around the young stars
Why?
As the gas cloud collapses it starts to spin and flatten out
Think Figure Skaters and Pizzas
formation of planetary systems is thought to be a natural result of star formation

15. Why did the gas cloud suddenly collapse?
We have no clue
May have been a passing star near the gas cloud
We think it was a nearby supernova shockwave that smooshed up the gas against itself

16. Pinwheel Galaxy –21 mly from Earth

18. Step 1 –formation of a star
stars form in massive and dense clouds of molecular hydrogen—giant molecular clouds (GMC).
gravitationally unstable
matter coalesces to smaller denser clumps
Collapses to form proto-stars that will eventually end up as
Brand new stars! 
star formation produces a gaseous proto-planetary disk around the young stars
formation of planetary systems is thought to be a natural result of star formation
sun-like stars usually take about 50 million years to form

19. Step 2 – form terrestrial planets
Proto-planetary disks are accretion disks which continue to feed the central star.
But, If the disk is massive enough, accretions begin in outer areas as well
small dust grains and rocks are plentiful and coagulate into kilometers-wide sized planetesimals
rapid—100,000 to 300,000 years—formation of Moon- to Mars-sized planetary embryos.
the planetesimals go through violent mergers, producing a few terrestrial planets.
Planets take around 100 million to a billion years to form

21. Planetesimal Planetesimal Collisions

22. Pause
Please head to Google Classroom and work on the activity posted there.
You need to answer 7 questions, so you have 7 minutes.
Well, now less than 7 minutes…..
The worksheet is posted on the assignment as a pdf
Your answer sheet is a google doc with your name already on it (you have to OPEN THE ASSIGNMENT to see it)

23. Step 2 – form terrestrial planets
Proto-planetary disks are accretion disks which continue to feed the central star.
But, If the disk is massive enough, accretions begin in outer areas as well
small dust grains and rocks are plentiful and coagulate into kilometers-wide sized planetesimals
rapid—100,000 to 300,000 years—formation of Moon- to Mars-sized planetary embryos.
the planetesimals go through violent mergers, producing a few terrestrial planets.
Planets take around 100 million to a billion years to form
-- Gases don’t condense into ice but instead get blown outward by the solar wind

24. Step 3 –form the gas giants
beyond the “snow line” planetary embryos begin to form and are mainly made of various ices.
Now you can also use things like frozen methane, water and ammonia
Also several times more massive than the inner part of the disk
Ices stick together better than rocks, so they grew in size more efficiently
formation of giant planets is a more complicated process
some embryos appear to continue to grow and eventually reach 5–10 Earth masses—the threshold value, which is necessary to begin accretion of the hydrogen–helium gas from the disk.
accumulation of gas by the core is initially a slow process, which continues for several million years
after the forming proto-planet reaches about 30 Earth masses it accelerates and proceeds in a runaway manner.

25. 3 –gas giants
Jupiter and Saturn–like planets are thought to accumulate the bulk of their mass during only 10,000 years. The accretion stops when the gas is exhausted.
Because their gravity is so strong, the newly formed planets can migrate over long distances during or after their formation.
The ice giants like Uranus and Neptune are thought to be failed cores, which formed too late when the disk had almost disappeared.

26. The Nebular Theory

27. This accounts for the other solar system stuff too…
Moons
Comets/icy planetesimals
Asteroids
Dwarf planets
Kuiper belt & Oort cloud objects
Rings