Solar System Lesson for Wednesday

1. Solar System Lesson for Wednesday • Engage: Review a picture of the planets • Explore: Analyze clues to the solar systems’ formation • Explain: Develop a class model of solar system formation, compare with a scientifically accepted formation model • Describe the concepts of gravity • Relate to general make-up of the solar system • Extend: Life in the solar system • Hypothesize where life might be possible in the solar system • Briefly discuss the wide diversity of life on Earth • Discuss the effects of gravity on the characteristics of an atmosphere • Evaluate: Given the characteristics of extra-solar planets, make a supportable prediction about the characteristics of its atmosphere.

2. Eight planets of our solar system • Compare/contrast the 8 planets in our solar system with each other. • How are they alike? How are they different? • Is there a pattern to their similarities or differences? Engage

3. General lesson learning progression • Learning target: Earth is the third planet from the Sun in a system with eight planets. These planets differ in size, composition, and atmosphere. These differences originated very early in the formation of the solar system (6-8 ES1B) • What students need to know • Planets: objects that orbit the Sun, are spherical and have cleared their orbit of debris • Density: mass/volume • Gravity: the pull objects have on each other because of their mass • Atmosphere: the gas gravitationally bound to a planet • What students need to do • interpret graphs • make inferences from data Explore

4. Solar System formation activity • You will get a clue (observable fact) about the formation of the solar system 1. What does your single clue tell you about how the solar system was formed?  2. Find two classmates with different clues. What does the set of three clues tell you about how the solar system was formed?  3. Look at all of the clues. What does the set of all of the clues tell you about how the solar system was formed? Relate each inference you make to a specific clue 4. Each group will pick a representative description to read to the class. Explore

5. Solar system formation clues • All planets orbit in nearly the same plane • All planets revolve around the Sun counterclockwise as viewed above Earth’s North Pole • Nearly all planets rotate counterclockwise as viewed above Earth’s North Pole • All four inner planets have a high mean density • All four outer planets have a low mean density • All of the giant planets have rings • Earth, Mars, meteorites and Sun are all about 4.6 billion years old • The Sun rotates counterclockwise as viewed above Earth’s North Pole Explore

6. More about ages • Oldest Earth rock – 4.3 b yrs (based on radioactive dating) • Oldest Moon rock – 4.5 billion yrs • Oldest Mars rock – 4.6 billion yrs • Oldest meteorite – 4.6 billion yrs • Sun’s age (based on rate of nuclear reactions at the Sun’s core) – 5.0 billion years • Many different clues point to an old solar system • Concepts in science class are based on the best available evidence • Most mainline religious denominations agree with the finding of an old solar system Explore

7. The Origin of the Solar System • Our own planetary system formed in such a disk-shaped cloud around the sun. • When the sun became luminous enough, the remaining gas and dust were blown away into space—leaving the planets orbiting the sun. • Simulation of this process Explain

8. Main builder of the solar system: Gravity • Newton’s three laws of motion • Newton’s Law of Universal Gravitation Explain

9. Newton's three laws of motion • From his study of the work of Galileo, Kepler, and others, Newton extracted three laws that relate the motion of a body to the forces acting on it. Explain

10. Newton's law of universal gravitation • Forces occur in pairs. • Gravity must be universal. • That is, all objects that contain mass must attract all other masses in the universe. • The force of gravity decreases as the square of the distance between the objects increases. • If the distance from the Earth to the moon were doubled, the gravitational force between them would decrease by a factor of 22, or 4. • If the distance were tripled, the force would decrease by a factor of 32, or 9. • This relationship is known as the inverse square relation. Explain

11. "Misconception minute": Mass vs weight • The massof an object is a measure of the amount of matter in the object—usually expressed in kilograms. • Mass is not the same as weight. • An object’s weight is the force that Earth’s gravity exerts on the object. • Thus, an object in space far from Earth might have no weight. • However, it would contain the same amount of matter and would thus have the same mass that it has on Earth. Explain

12. Planet densities • What general pattern(s) do you observe about the density variation? • How does this pattern relate to the accepted model of solar system formation? • Write your answers in your notebook. • Pick a representative entry to read to the class. Explain

13. Formative feedback loop for composition Solicit student evidence: Asked question about planet density variation and relationship to our model Provide standards-focused feedback: Related each group’s response the standard (composition difference) and a key skill (infer from data) Evaluate student understanding: Each group read their response.

14. Big picture statement of solar system formation: The important factor was temperature. • The inner nebula was hot, and only metals and rock could condense there. • The cold outer nebula could form lots of ices in addition to metals and rocks. • The ice line seems to have been between Mars and Jupiter—it separates the formation of the dense terrestrial planets from that of the low-density Jovian planets. Explain

15. Applying your knowledge • You will apply your knowledge about planet characteristics and density to infer where in the solar system, besides Earth, life might be found. • Five main criteria to investigate to determine if life is possible • Temperature, Water, Atmosphere, Energy, Nutrients • Each group will decide whether life is likely, possible or unlikely for each object. • Decide on your top three candidates for life (in order, excluding Earth) • Trading cards and other astrobiology curriculum Extend

16. Omak choices: most likely for life Defend your top choice with a 2-3 sentence paragraph that includes supporting evidence. Read your sentence to the class. Extend

17. Wenatchee choices: most likely for life Defend your top choice with a 2-3 sentence paragraph that includes supporting evidence. Read your sentence to the class. Extend

18. Extreme Environments on Earth • Sea Ice (extreme cold) • Hydrothermal vents (extreme heat and high metal content) • Sulfuric Springs (extreme heat and highly acidic) • Salt Lake (extreme salt concentrations) • Soda Lake (extreme salt concentration and highly alkaline) Extend

19. Importance of Extremophiles: Astrobiological Implications • Extreme environments on Earth are thought to be very similar to extreme environments that exist elsewhere in space • Microorganisms that thrive in Earth extreme environments are thought to be likely candidates for the types of biota that may exist in extraterrestrial habitats • Mars is postulated to have extremophilic regions including permafrost, hydrothermal vents, and evaporite crystals • Europa is thought to have a subsurface ocean Mars Extend Europa

20. Planetary atmospheres • A combination of a planet’s gravity and surface temperature influence its atmosphere. • Larger planets have a greater gravitational pull on particles in their atmosphere. • The mean velocity of a bunch of particles is set by the temperature of the planet's surface. • Light elements are moving faster than the heavy elements and can reach escape velocity. Evaluate

21. Mystery planet atmospheres System A characteristics • Planet A: Upsilon Andromedae c • Twice the mass of Jupiter • 0.83 AU from its star (Earth is 1.0 AU from the Sun) • Star A: Upsilon Andromedae • Nearly the same size and temperature as the Sun System B characteristics • Planet B: Gliese 581 d • 7X the mass of Earth (Uranus is 14X mass of Earth) • About 0.2 AU from its star (Mercury is 0.4 AU from the Sun) • Star B: Gliese 581 • About one third the radius and mass of the Sun • T=3,000oc (Sun T=6,000oc) Evaluate

22. Mystery planet atmospheres • Use the planet and star characteristics as well as the escape velocity vs. temperature graph to make a supportable prediction about the atmosphere of each mystery planet. • Write your predictions and supporting evidence in your notebook. • Pick a representative prediction (with support) to read to the class. Evaluate

23. Sample supportable predictions Upsilon Andromedae c • Since this planet is more massive than Jupiter, it has a large gravitational pull and higher escape velocity than Jupiter. • It is closer to its star than Jupiter but the additional heat does not make many particles in the atmosphere move fast enough to escape. • This planet has an atmosphere dominated by H and He. Gliese 581 d • Since this planet is half the mass of Uranus, it has a smaller escape velocity. • It is closer to its star than Mercury but its star is much cooler than the Sun meaning it will be cooler and the atmosphere particles not moving as fast. • This planet would probably be located near or below the He line on the graph meaning it would have little or no H and could be more Earth-like. Evaluate

24. Formative feedback loop for atmosphere Solicit student evidence: Asked question about planet atmosphere Provide standards-focused feedback: Related each response the standard (atmosphere difference) and a key skill (infer from data) Evaluate student understanding: Instructor briefly read each student response.