Comparative Planetology

1. Comparative Planetology A systems approach to understanding our Solar System

2. Donna GovernorLiberty Middle SchoolCumming, GA • Gifted Science, grades 6, 7 & 8 • Co-Instructor: Comparative Planetology (NTEN) • Teaching Assistant: Astronomy for Teachers (NTEN) • 23 Year Veteran, K-8 dgovernor@forsyth.k12.ga.us

3. A Systems Approach to Planetary Science Our Solar System is more than just eight planets that orbit a star; it includes hundreds of diverse worlds interacting as a dynamic system. According to the National Science Standards,”a major goal of science in the middle grades is for students to develop an understanding of Earth and the Solar System as a set of closely coupled systems.” With 8 planets, 140+/- moons, and thousands of Minor Planets, our Solar System is a rich collection of worlds which should be explored with a systems approach. The unit shared in this session looks at the Solar System with a “Comparative Planetology” approach. The worlds of our Solar System are compared in terms of orbits, interiors, surfaces and atmospheres. This systems-approach unit is multi-disciplinary, and incorporates Reading in the Content Area, Music, Labs and Technology.

4. Comparing Systems Orbits Interiors Surfaces Atmospheres

5. Integrating Reading in the Content Area Planetology: Comparing Other Worlds to Our Own by Fred Schaaf ISBN: 0531158284 • Following the Wanderers • Survey of the Planets • Planetary Interiors & Magnetospheres • Planetary Surfaces • Planetary Atmospheres • Lifesaving Lessons from the Planets • History of the Solar System • The Future

6. Our Solar System Terrestrial Worlds: • Rocky and small • Few moons, no rings • Up to 2.5 AUs Asteroid Belt, ~ 3 AUs Jovain Planets • Gaseous and BIG! • Many moons, with rings • 5-30 AUs

7. Our Solar System ALSO includes: Kuiper Belt • Area of small objects orbiting the Sun, includes Pluto & other Dwarf Planets, extending past the orbit of Neptune - 30 to about 50 Aus Oort Cloud • Source of Long Period Comets - a spherical region about 50,000 AUs from the Sun.   Images from: http://www.windows.ucar.edu

8. Solar System Formation The accretion model explains that the worlds in our solar system condensed from material in the Solar Nebula. As the protoplanetary disk cooled, materials in the disk collided and condensed into planetesimals, which eventually became the worlds of our Solar System. • Planet type formed depended on distance from Sun – based on condensation and temperature at time of planetary formation • A frost line between Mars and Jupiter resulted in two types of planets • Near the Sun, where temperature is high, metals and rocks condensed. • Past the frost line, gases and ice were able to condense, forming the gas giant planets and their icy moons.

9. Orbits Planets Orbit the Sun at different distances – each planet has a minimum, maximum and average orbit, although some have a larger range than others. Johannes Kepler, an assistant to Tycho Brahe, formulated Three Laws of Planetary Motion utilizing the data Brahe accumulated. 1. The Law of Elipses: All planets move in elliptical orbits, with the sun at one focus. 2. The Law of Areas: A line that connects a planet to the sun sweeps out equal areas in equal times. 3. Harmonic Law: The square of the period of any planet is proportional to the cube of the semimajor axis of its orbit.

10. Toilet Paper Scale Model Scale: 1 AU = 5 sheets • Mercury - min 1.5, avg2.0, max 2.4 • Venus – min 3.6, avg3.7, max 3.7 • Earth – min 5.0, avg5.1, max 5.2 • Mars – min 7.0, avg7.7, max 8.4 • Asteroids - min 9, avg 14, max 22 • Jupiter – min 25.1, avg26.4, max 27.7 • Saturn – min 45.7, avg48.4, max 51.1 • Uranus – min 92.7, avg97.3, max 101.8 • Neptune – min 151.1, avg 152.4, max 153.8 • Pluto- min 150.0, avg 200.0, max 250.0 Don’t forget the Habital Zone: .84 – 1.7 AUs Activity Link: http://www.nthelp.com/eer/HOAtpss.html

11. Ellipse Length of Major Axis A: Length of Semi-Major axis C: from the Center to Foci Eccentricity C/A 1 2 3 Integrating Math: Drawing Ellipses An ellipse has two interior points called foci, a long axis (the major axis), a short axis (the minor axis), and a center. Half of the major axis is called the semi-major axis, whichis also the average sun-planet distance. Eccentricity refers to how elliptical an orbit is, and is calculated using the formula: e = c/a • a is the semi-major axis • c is the distance from the center to either foci • Insert two push pins into the x-axis equidistant a center where the x and y axis intersect • Form a triangle from the string by looping it around both push pins and your pencil. 3. Tension the string with the point of a pencil and, keeping the string taut, trace out an ellipse. Activity Link: http://genesismission.jpl.nasa.gov/educate/scimodule/ DestinationL1/DL1_PDFs/3_science/SA-Round&Round.pdf

12. Tycho Brahe gathered lots of data But someone had to show what it all meant The church said planets gotta make round trips Kepler said, “kiss my ellipse!” Your epicycles gotta hit the road Cause the orbits are all bent! Said Kepler – said Kepler – He figured out the dance These three little rules will be our tools And leave not a bit to chance! Planets make an ellipse with the sun as a focus The other focus is just empty space But draw two lines from the foci to the planet You add ‘em up and the sum is constant Works the same in every case Said Kepler – said Kepler – He figured out the dance These three little rules will be our tools And leave not a bit to chance! Planets sweep out equal areas in equal times All those triangles add up just the same When the planet gets too near the sun It whips around like it’s having fun When you’re far gotta walk When you’re close gotta run That’s how you play that area game Integrating Music: Said Kepler Said Kepler – said Kepler – He figured out the dance These three little rules will be our tools And leave not a bit to chance! The square of the period follows the cube of the distance The average distance of planet to the sun If your radius is two, the rule’s gonna state That your orbital time is the square root of eight You’d better hurry up so you won’t be late If you’re real close in then you really gotta run! Said Kepler – said Kepler – He figured out the dance These three little rules will be our tools And leave not a bit to chance! Now Kepler’s laws were marvels of precision Reducing orbital complexity Then Isaac Newton came along And said, pretty good, but your premise is wrong You figured out the dance but I heard the song How ‘bout one rule to replace all three Said Newton – said Newton – that apple’s got to fall Here’s one great law that explains what you saw Gravity says it all! Activity Link: www.professorboggs.com

13. Interiors & Magnetospheres Image from: http://www.astronomynotes.com/solarsys/s8.htm The interiors of the planets are determined based on data including: orbital distance, mass, density and chemical composition. Magnetic fields provide clues to differentiated cores and protects the planet from high energy particles from the Solar Wind.

14. Density of icy Moons Using the information about the density of a planet or moon, you can determine its composition. Moons are usually composed of rock and ice, and the composition of these worlds is determined using their density. Rock has an average density of 3.5 g/cm3. Water ice has a density of about .9 g/cm3 We can determine the composition of each satellite by using the known densities of rock and water ice to determine the relative percentage of rock and ice in each world. First, we must calculate the density of various rock & ice combinations using the following formula: Density = (% Rock X Density Rock) + (% Ice X Density Ice) / 100 Activity Link: http://www.spacegrant.hawaii.edu/class_acts/RockyIcyMoonTe.html

15. Lab Activities: Magnetic Fields Drawing Magnetic Fields: • Place a magnet under an image of the Earth. Sprinkle with iron filings, observe Earth’s Magnetic Field Activity Link: http://media.nasaexplores.com/ lessons/02-002/k-4_1.pdf Magnetic Field & Function Cereal Lab: • Mix cereal with iron filings to observe what happens to Solar Wind when mixture is dropped in beaker of oil between two magnets Activity Link: http://sprg.ssl.berkeley.edu/ aurora_rocket/education/cereal/lessonplan.pdf

16. Planetary Surfaces The surfaces of all terrestrial worlds are shaped by four essential processes: • volcanism - caused by molten or hot rock from the interior erupting on the surface • impact craters - caused by an impact on the surface from rocks or other material • erosion/volatiles - caused by weathering (water or wind) or vaporization of the surface • tectonics - caused by folding and faulting forces which deform the surface "Nomenclature" means a system for naming things. And just like on Earth where mountains, rivers and other features are named, surface features on other worlds are also named.

17. Cratering on Planetary Surfaces Craters provide clues to a planet’s history. The size, shape and overlaying features tell a story about a world’s past. On planetary surfaces where craters have been erased, other processes are indicated. Inquiry Activity: What factors affect the size of a crater? Variables include: Size of impactor, density of surface, angle of impact…. Test as many as possible! Activity Link: http://deepimpact.jpl.nasa.gov/educ/DesigningCraters.html

18. Planet Trek Similar processes have shaped the surfaces of all known worlds. In these activities students will explore surface features of nearby worlds, learn how planetary features are named and create maps of their surface features. Finally, students will create their own extra-solar worlds using potatoes, then name and map their unique world's surface features. Activities Include: • Activity #1 - Comparing Surfaces • Activity #2 - Terrestrial Surface Features • Activity #3 - Surface Processes • Activity # 4 – Planetary Nomenclature • Activity # 5 - Map Features by Lat & Lon • Activity # 6 - Potato Worlds Activity Link: http://btc.montana.edu/ceres/Worlds/Landform/planettrek.htm

19. Planetary Atmospheres On Earth, it is our atmosphere that allows our planet to support life. How does our atmosphere compare to others? Jovian worlds: Mostly hydrogen & helium, ammonia & methane also Terrestrial worlds: Include heavier elements, nitrogen, oxygen, carbon dioxide; small worlds not enough gravity/mass to hold atmosphere

20. Why is the Sky Blue? • Cut two pieces of glue stick: one 1.3 cm and one 6.3 cm. • Glue the hot glue sticks to the template on the parallel lines. • Glue a piece of a Styrofoam peanut where the house is. • Darken the room. • Use a mini flash light to shine through the length of each glue stick, onto the house. • Compare the color of the light as it passes through each glue stick. Activity Link: http://www.nthelp.com/eer/HOAbluesky.html

21. Integrating Technology: Online Simulator Use this simulator to explore the Greenhouse Effect! This online Greenhouse Simulator shows the Earths’ surface and landscape at different time periods. A thermometer indicates the temperature. The yellow “drops” indicate incoming solar radiation – light from the Sun in the visible portion of the spectrum. Once photons are absorbed by the Earth’s surface, energy is absorbed and reflected back into the atmosphere as infrared light – heat. When visible light is reflected and not absorbed, the temperature of the surface drops. When infrared light is trapped, the temperature rises. Activity Link: http://www.colorado.edu/physics/phet/simulations/greenhouse/greenhouse.jnlp

22. Planetary Trading Cards CulminatingActivity The front of each planet card will have: • The name & a picture of the planet • Two interesting facts about it. Backs of planet cards will have: • Orbital distance from the Sun in A.U.’s • Orbital velocity, period & eccentricity • Planet’s mass, density & diameter • Planet’s structure (Core, Layers, Density & Composition) • Atmospheric data (incl. chemical composition of gas giants) • Number of moons & names of major moons • Information on rings, if any • Period of rotation (in Earth days) • Surface features Alternate idea: Make a Travel Brochure

23. Activities Summary Orbits: • Toilet Paper Scale Model: http://www.nthelp.com/eer/HOAtpss.html • Drawing Ellipses: http://genesismission.jpl.nasa.gov/educate/scimodule/DestinationL1/DL1_PDFs/3_science/SA-Round&Round.pdf • “Said Kepler” (Music): http://www.professorboggs.com Interiors: • Density of Icy Moons: http://www.spacegrant.hawaii.edu/class_acts/RockyIcyMoonTe.html • Drawing Magnetic Fields: http://media.nasaexplores.com/lessons/02-002/k-4_1.pdf • Magnetic Field Cereal Lab: http://sprg.ssl.berkeley.edu/aurora_rocket/education/cereal/lessonplan.pdf Surfaces: • Deep Impact: http://deepimpact.jpl.nasa.gov/educ/DesigningCraters.html • Planettrek: http://btc.montana.edu/ceres/Worlds/Landform/planettrek.htm Atmospheres: • Blue Sky: http://www.nthelp.com/eer/HOAbluesky.html • Online Greenhouse Simulator: http://www.colorado.edu/physics/phet/simulations/greenhouse/greenhouse.jnlp

24. Thank you!Donna Governordgovernor@forsyth.k12.ga.us Comparative Planetology A systems approach to Planetary Science