1. The Earth

2. The Solar System 太陽系 Note: Pluto ( 冥王星 ) was recently removed from the list of planets. In 2006, it was redefined as a dwarf planet. Image Source: moulinlesetoilesmoulinlesetoiles

3. The Planets to Scale Inner PlanetsOuter Planets Mercury, Venus, Earth, and Mars Rocky planets Jupiter, Saturn, Uranus, Neptune “Gas giants ” Our home: just a tiny speck of rock in space?

4. The size of the Earth relative to the Sun Image source: www.physics.uci.eduwww.physics.uci.edu

5. The size of the Sun relative to some other stars Image source: www.physics.uci.eduwww.physics.uci.edu

6. Has largest satellite (moon) compared to its own diameter; the Moon helps to keep the Earth’s tilt stable. Abundant water in the atmosphere. At the right distance from the Sun to have liquid water. Only planet in the solar system to have open oceans. Because water can dissolve CO 2, the Earth was saved from a “runaway greenhouse effect.” (Compare with Venus.) O 2 -rich atmosphere (21% O 2 by volume) Magnetic field that protects the planet from solar wind Life! Living organisms cover the Earth. There is no definite evidence yet for any other biospheres in the solar system… or, at this point, in the universe…. From our perspective, however, the Earth has many special characteristics!

7. “Habitable Zone” of Sun – Distance from a star at which it is theoretically possible for a planet with sufficient atmospheric pressure to maintain liquid water on its surface. Inner edge - 0.95 AUOuter edge - 1.37 AU Image Source: DMNSDMNS

8. “The Goldilocks Planet” Just right! Illustration: Arthur Rackham

9. The Earth’s Outermost Layers – Interconnected Systems The atmosphere The biosphereThe hydrosphere The lithosphere (geosphere) Image: http://www.gly.bris.ac.uk/www/ESS/index.htmlhttp://www.gly.bris.ac.uk/www/ESS/index.html

10. Atmosphere ( 大氣圈 ) Thin gaseous envelope surrounding Earth Hydrosphere ( 水圈 ) Water layer ; most water is in the oceans Biosphere ( 生物圈 ) All living things on the planet Lithosphere ( 岩石圈 ) OR Geosphere Rocky outer shell of Earth; made of up plates that have moved through the Earth’s history The Earth’s Outermost Layers – Interconnected Systems

11. Some translate lithosphere as 土石圈 (Soil-Rock Sphere)… We can’t forget the soil. It’s not very exciting, but our lives depend on it. It’s sort of the meeting place of the four spheres—the result of air, water, and organisms acting on rock.

12. The Atmosphere ( 大氣圈 ) Composition is unique in the solar system 78% N 2, 21% O 2 Minor amounts of CO 2, argon, and water vapor O 2 is directly linked to the presence of life on Earth. It is produced mainly by photosynthesis. Free O 2 is very reactive and would not remain in an atmosphere without life.

13. The Atmosphere (cont’d.) The atmosphere makes up only one-millionth of earth’s mass, but it is VERY important: Protects the earth from harmful radiation Controls climate; creates a beneficial greenhouse effect. Supports the majority of life forms that need to take in its gases to live.

14. The Atmosphere What kind of radiation does it keep out? What forms of radiation reach the Earth’s surface? Image Source: redorbit.comredorbit.com

15. The hydrosphere ( 水圈 ) 75% of the Earth’s surface is covered by oceans For the last ~3.8 billion years, the Earth has had a relatively stable water cycle (see video), with possibly a few freeze-ups or “Snowball Earth” episodes…video The planets are misnamed in Chinese: Earth is the “Water Planet,” not Mercury ( 水星 )!

16. Liquid water is essential for life as we know it. The biochemical reactions that sustain life need a fluid in order to operate; in a solid, getting molecules where they need to go is difficult. Compared to most other liquids, water also has an extremely large liquid range. Water is probably the best solvent in the universe.

17. It’s hard to imagine waterless life. Other liquids just don’t work: Ammonia (NH 3 ) - liquid range is small, only about 30 degrees C (compared to 100 degrees for water) Methane (CH 4 ) – a liquid at -150 K, but at that temperature, other chemical reactions are too slow…

18. The Biosphere ( 生物圈 ) Consists of all life on Earth Microscopic organisms are the most common life forms and are essential for supporting the bigger life forms. Phytoplankton (microorganisms that live in water and convert the Sun’s energy into chemical energy) produce half of the oxygen in the Earth’s atmosphere. We can’t live without them ! THE BIOSPHERE IS THIN!  For a scale model, take a piece of paper. Fold once. Paste on a basketball.

19. The Earth has a layered structure Compositional Layers Crust – Silicates and aluminosilicates Mantle – Silicates rich in iron and magnesium Core – Iron, nickel Physical Layers Lithosphere – Rigid plates Asthenophere - Plastic Mesophere – Denser, more rigid than asthenophere Outer Core - Liquid Inner Core - Solid

20. 岩石圈 軟流圈 中層圈 地核 外部地核 內部地核 地函 地殼 地函 The Earth’s Layers Image Source: J. Varekamp,J. Varekamp

21. Let’s start at the Earth’s center and work outward!

22. INNER CORE ( 內部地核 ) -HOT!!!! ~9000 C -Solid -Composed of Fe and Ni. http://www.sciencenewsforkids.org/articles/20030521/a48_1477.jpg

23. OUTER CORE ( 外部地核 ) HOT! (but not as hot as the inner core) Liquid Composed of Fe and Ni The Earth's magnetic field is mostly caused by electric currents in the liquid outer core. http://www.sciencenewsforkids.org/articles/20030521/a48_1477.jpg

24. The Earth’s Magnetic Field – deflects the solar wind Without this field, the solar wind would erode the Earth’s atmosphere and would shower the Earth with particles that could damage the DNA of living things. Artist’s rendering, not to scale. http://en.wikipedia.org/wiki/File:Magnetosphere_rendition.jpg http://en.wikipedia.org/wiki/File:Magnetosphere_rendition.jpg

25. MANTLE ( 地函 ) Still hot! – but not as hot as the core! Still hot! – but not as hot as the core! Largest layer Largest layer – 2900 km thick – 82% by volume – 68% by mass Composed of silicate rocks with abundant iron and magnesium Composed of silicate rocks with abundant iron and magnesium http://www.sciencenewsforkids.org/articles/20030521/a48_1477.jpg

26. CRUST ( 地殼 ) Two types: Continental crust  Thick - up to 75 km  Lower density - 2.7 g/cm 3  Strongly deformed  May be billions of years old Oceanic crust  Thinner - about 8 km  Dense - 3.0 g/cm 3  Comparatively undeformed  Younger - < 200 million years old http://www.sciencenewsforkids.org/articles/20030521/a48_1477.jpg

27. The lithosphere ( 岩石圈 ) - the outer part of the earth that consists of rigid plates Includes the crust and the rigid part of the upper mantle http://www.physicalgeography.net/fundamentals/10h.html

28. Main features of plate tectonics 板塊構造學說 The Earth's lithosphere consists of plates that are moving relative to one another. The ocean floors are continually spreading from the center and sinking (being subducted) at the edges. Convection currents in the asthenosphere probably cause plate motion. The source of heat that drives the convection currents is radioactivity deep in the Earth.

29. The Earth’s Major Tectonic Plates ( 分離板塊邊緣 )( 聚合性板塊邊緣 )( 轉形斷層 ) www.sci.uidaho.edu/geol111/geology_101.htm

30. The Plate Tectonics Model Convection ( 對流 ) in the asthenosphere may drive plate motions; magnetic “stripes” on the ocean floor record the Earth’s magnetic field at the time the ocean crust cooled.

31. Three Types of Plate Boundaries 板塊邊緣 Divergent ( 分離板塊邊緣 ) – Plates moving apart Convergent ( 聚合性板塊邊緣 ) – Plates moving toward each other Transform ( 轉形斷層 ) – Plates sliding past each other

32. Plate Boundaries Image source: WikipediaWikipedia Three Types of Plate Boundaries

33. Plate tectonic setting of Taiwan What kind of plate boundary does Taiwan sit on? Image from Wang, C.Y. et al. (2001)Wang, C.Y. et al. (2001)

34. Answer: Taiwan sits on a very complicated convergent boundary (island arc – continent collision) If any subduction were occurring we would have a volcano erupting in Kenting…

35. Scheme proposed by Chemenda et al. (2001) for the arc-continent collision that produced the island of Taiwan. An island arc is not dense enough to be subducted, so when it arrives at the subduction zone, subduction shuts down.

36. Geologically dead  Biologically dead? Is plate tectonics necessary for life? Plate tectonics and liquid water seem to need each other. If one disappears, so does the other. Mercury and Moon – Geologically dead for 4 billion years… Mars – Tectonic activity may have started but was stopped by the planet’s rapid cooling… Venus – Like the very young earth??? The crust may be too hot for plates to form. Surface of Venus is bone dry with temperatures near 800 o Earth – Just right!