 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. 1.Complex Knowledge: demonstrations of learning that go aboveand above and beyond what was explicitly taught. 2.Knowledge: meeting the learning goals and expectations. 3.Foundational knowledge: simpler procedures, isolated details, vocabulary. 4.Limited knowledge: know very little details but working toward a higher level.

 Find DENSITY for each planet  Find 2 patterns in the solar system  Record any ideas in your notebook

 What events and materials were necessary to form our solar system?

1. 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). 2. 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). 3. Terrestrial planets are dense, rocky and small, while Jovian planets are gaseous and large.

 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%

 Nebular theory is the most widely accepted model explaining the formation of the Solar System.  First proposed with evidence:  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.

 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 stars  star formation produces a gaseous protoplanetary 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

 SolarSystemFormation.mov SolarSystemFormation.mov

 protoplanetary disks are accretion disks which continue to feed the central star.  very hot, but condensation can occur  small dust grains made of rocks and ice are possible  grains may coagulate into kilometer sized planetesimals  If the disk is massive enough, accretions begin  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

 ts102/mario/images/planetesimals.mov ts102/mario/images/planetesimals.mov  ts102/mario/images/planetesimal_collisions. mov ts102/mario/images/planetesimal_collisions. mov

 beyond the “snow line” planetary embryos begin to form and are mainly made of various ices.  several times more massive than in the inner part of the disk.  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 protoplanet reaches about 30 Earth masses it accelerates and proceeds in a runaway manner.

 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.  The 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.

 Moons  Comets/icy planetesimals  Dwarf planets  Kuiper belt & Oort cloud objects  rings

 Read article: Formation of the Solar System (2 pages)