Chapter 4 The Solar System

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1 Chapter 4 The Solar System

2 Comet Tempel

3 Chapter overview Solar system inhabitants Solar system formation Extrasolar planets

4 Solar system inhabitants Sun Planets Moons Asteroids Comets Meteoroids Kuiper Belt Objects

5 Figure 4.1 Solar System

6 Planets Orbital size Orbital period Mass Radius Moons Density (water density is 1000 kg/m 3 )

7 Table 4-1 Properties of Some Solar System Objects

8 Planetary orbits Lie in same plane (ecliptic plane) Mercury and Pluto are slight exceptions Orbit around sun in same direction

9 Figure 4.2 Planetary Alignment

10 Terrestrial planets Mercury Venus Earth Mars

11 Jovian planets Jupiter Saturn Uranus Neptune Memory aid: S-U-N

12 Figure Sun and Planets

13 Table Comparison Between the Terrestrial and Jovian Planets Table 4-2 Comparison Between the Terrestrial and Jovian Planets

14 Other planet? Pluto As of late 2006, demoted from a planet

15 Interplanetary matter Asteroids Comets Meteoroids

16 Figure 4.4 Inner Solar System

17 Asteroids Asteroid belt Between orbits of Mars and Jupiter Noticeably elliptical orbits Trojan asteroids Earth crossing asteroids Up to 1000 km in size

18 Figure 4.5 Asteroids, from Earth

19 Figure 4.6 Asteroids, Close-up a) Gaspra b) Ida with Dactyl c) Mathilde

20 Asteroid types Carbonaceous Dark, water ice and organics (carbon) Silicate Reflective, more rocky Inner portion of asteroid belt

21 Figure 4.7 Asteroid Eros

22 Discovery 4-1a What Killed the Dinosaurs?

23 Discovery 4-1b What Killed the Dinosaurs?

24 Figure 4.8 Halley s Comet

25 Comets Nucleus Coma (dust and evaporated gas) Hydrogen envelope Ion tail Dust tail Tails directed away from sun

26 Figure 4.9 Comet Tails - Comet Hale-Bopp 1997

27 Figure 4.10 Comet Trajectory

28 Figure 4.11 Halley s Comet Close-up from Giotto spacecraft in 1986

29 Figure 4.12 a) Comet Wild-2 from Spacecraft Stardust b) aerogel for comet dust

30 Short period comet orbits Short period (< 200 years) Kuiper belt (beyond Neptune) 30 to 100 AU from sun Roughly circular orbits, in ecliptic plane Occasionally kicked into inner solar system About 900 Kuiper belt objects (KBO) known Some KBO s larger than Pluto

31 Long period comet orbits Long period (> 200 years) Oort cloud Up to 100,000 AU diameter Random orbital orientation Occasionally kicked into inner solar system

32 Figure 4.13 Comet Reservoirs

33 Meteor terminology Meteoroid (chunk of space debris) Meteor (streak of light in sky) Meteorite (piece of meteoroid that falls to ground) Micrometeoroids Meteoroid swarm or shower (cometary debris)

34 Figure 4.14 Meteor Trails

35 Figure 4.15 Meteor Showers

36 Table 4.3 Some Prominent Meteor Showers Table 4-3 Some Prominent Meteor Showers

37 Figure 4.16 Radiant

38 Figure 4.16 Analogy Railroad Tracks Converging

39 Meteor craters on earth About 100 craters over 100 m in diameter Others heavily eroded by weather or geological activity

40 Figure Barringer Crater, Arizona

41 Figure 4.18 Manicouagan Reservoir, Quebec

42 Figure 4.19 Tunguska Debris (Siberia, 1908)

43 Meteorite types Rocky silicate Iron with some nickel Carbonaceous 4.4 to 4.6 billion years old

44 Figure Meteorite Samples (a) rocky or stony (silicate) (b) iron and some nickel

45 Model of Solar System formation must explain 1. Each planet isolated 2. Planet orbits nearly circular 3. Planet orbits nearly lie in a plane 4. Planets orbit sun in same direction sun rotates 5. Most planets rotate in same direction sun rotates 6. Most moons revolve in direction planet rotates 7. Terrestrial vs. Jovian planets 8. Asteroids are old and are unlike planets 9. Kuiper belt objects 10. Oort cloud comets

46 Figure 4.21 Angular Momentum

47 Figure 4.22 Beta Pictoris

48 More Precisely 4-1 The Concept of Angular Momentum

49 More Precisely 4-1b Conservation of Angular Momentum

50 Figure Dark Cloud containing interstellar dust and gas

51 Formation of solar system Nebular contraction Spinning material flattens into pancake as it contracts Condensation of interstellar dust Accretion Millions of planetesimals Protoplanets Fragmentation Protosun

52 Figure 4.24 Solar System Formation

53 Figure 4.25 Newborn Solar Systems?

54 Jovian planets Outer planets grew rapidly Gravitationally attracted gas from solar nebula Or could have started as gravitational instabilities in solar nebula

55 Figure 4.26 Jovian Condensation

56 Figure 4.27 Temperature in the Early Solar Nebula

57 Figure 4.28 Planetesimal Ejection

58 Figure 4.29 Extrasolar Planet

59 Extrasolar planets Indirectly detected by motion of star Large Jupiter-like planets in small orbits Selection effect Only detect largest and closest to the star Is our solar system unique?

60 Figure 4.30 Planets Revealed

61 Figure 4.31 An Extrasolar Transit

62 Figure 4.32 Extrasolar Orbits

63 Figure 4.33 Sinking Planet