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.

Field Trip It is 40 dollars Trip is scheduled for March 2 We will return to school late – around 4:30 Permission and Money are due on Friday, January 20

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

Just so we are clear…

Kuiper Belt Pluto is most famous inhabitant Just outside of the orbit of Neptune Extends from ~30 to ~ 50/60 AUs from the sun Home of hundreds of thousands of icy bodies larger than 100 km (62 mi), and trillions of short period comets – those with orbits of a few hundred years or less Gerard Kuiper predicted it in 1950, we didn’t get proof of its existence until 1968 (that’s science!!)

Oort Cloud – Our Shell We haven’t found it, it’s only hypothesized Because comets come from all angles, up, down, left and right, they have to be chilling out there in all directions Too far away for us to see New Horizons will get there in around 500 years or so Extends from ~1000 to possibly~ 100,000 AUs from the sun That’s almost half way to the next star It would take New Horizons over 500 years to arrive

Oort Cloud – Our Shell Trillions of long period comets are predicted to live there Long period comets have orbits in the thousands of years or more Jan Oort predicted it in 1953, which is why it is named after him

Modeling Planet Formation Review of condensation theory: Large interstellar cloud of gas and dust starts to contract, heating as it does so Sun forms in center; dust provides condensation nuclei, around which planets form As planets grow, they sweep up smaller debris near them Figure 15-1. Solar System Formation The condensation theory of planet formation is artistically illustrated by these half-dozen changes, from infalling interstellar cloud at the top to newly emerged planetary system at the bottom. Compare to Figure 6.17, and consult the text opposite for descriptions of each of the frames of this figure.

Terrestrial Planets Terrestrial (rocky) planets formed near Sun, due to high temperature—nothing else could condense there. Figure 15-3. Making the Inner Planets Accretion in the inner solar system: Initially, many moon-sized planetesimals orbited the Sun. Over the course of about 100 million years, they gradually collided and coalesced, forming a few large planets in roughly circular orbits.

Terrestrial and Jovian Planets T-Tauri (baby) stars are in a highly active phase of their evolution and have strong solar winds. These winds sweep away the gas disk, leaving the planetesimals and gas giants. Figure 15-4. T Tauri Star (a) Strong stellar winds from the newborn Sun sweep away the gas disk of the solar nebula, (b) leaving only giant planets and planetesimals behind. This stage of stellar evolution occurs only a few million years after the formation of the nebula.

Jovian Planets Jovian planets: Once they were large enough, may have captured gas from the contracting nebula Figure 15-5. Jovian Condensation As an alternative to the growth of massive protoplanetary cores followed by the accretion of nebular gas, it is possible that some or all of the giant planets formed directly through instabilities in the cool gas of the outer solar nebula. Part (a) shows the same instant as Figure 15.2(b). (b) Only a few thousand years later, four gas giants have already formed, preceding and circumventing the accretion process sketched in Figure 15.2. With the nebula gone (c), the giant planets have taken their place in the outer solar system. (See Figure 15.2e.)

Jovian Planets Detailed information about the cores of jovian planets should help us determine how much rock and metal were present in the outer solar system Also possible: The jovian planets may have formed farther from the Sun and “migrated” inward.

Interplanetary Debris Icy planetesimals far from the Sun were ejected into distant orbits by gravitational interaction with the jovian planets, into the Kuiper belt and the Oort cloud. Some were left with extremely eccentric orbits and appear in the inner solar system as comets. Figure 15-7. Planetesimal Ejection The ejection of icy planetesimals to form the Oort cloud and Kuiper belt. (a) Initially, once the giant planets had formed, leftover planetesimals were found throughout the solar system. Interactions with Jupiter and Saturn apparently “kicked” planetesimals out to very large radii (the Oort cloud). Interactions with Uranus and especially Neptune tended to keep the Kuiper belt populated, but also deflected many planetesimals inward to interact with Jupiter and Saturn. (b) After hundreds of millions of years and as a result of the inward and outward “traffic,” the orbits of all four giant planets were significantly modified by the time the planetesimals interior to Neptune’s orbit had been ejected. As depicted here, Neptune was affected most and may have moved outward by as much as 10 AU.

Interplanetary Debris Kuiper belt objects have been detected from Earth; a few are larger than, Pluto, and their composition appears similar. About 1/3 of all Kuiper belt objects (including Pluto) have orbits that are in a 3:2 resonance with Neptune; such objects are called “plutinos.” We have never seen the Oort Cloud, but know it’s there because comets come cruising in from all directions

15.4 Solar System Regularities and Irregularities Condensation theory covers the 3 main points mentioned at the beginning. 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.

Summarizing: Read article: Formation of the Solar System (2 pages) Answer the 2 questions at the end of the reading Then answer the questions from Wednesday. What events and materials were necessary to form our solar system? How do planets differ from one another and why?

2 EdPuzzles – Due Today