Homework #5

1. Homework #5 What is the average speed of hydrogen atoms (m=1.67x10-27 kg) in the Sun’s photosphere (T = 5800 K)? What is the escape velocity from Mercury?

2. Mercury’s temperature range is the most extreme in the solar system • Daytime with the Sun overhead reaches 700K (or 800°F) • Midnight with the Sun completely obscured is 100K (or -280°F) • Earth typically has temperature differences between day and night of about 11K (or 20°F) • Mercury’s slow 176 day rotation and the lack of an appreciable atmosphere means temperatures vary enormously from one side of the planet to the other. Why is there no atmosphere on Mercury?

3. 4300 Average speed of particles in a gas on Mercury: Number of particles Speed of particles

6. The Outer Planets

7. Inner planets: Mercury Venus Earth Mars Outer planets: Jupiter Saturn Uranus Neptune

8. Jovian Planet Properties

9. Jovian Planet Properties • Compared to the terrestrial planets, the Jovians: • are much larger & more massive • are composed mostly of Hydrogen, Helium, & Hydrogen compounds • have no solid surfaces • rotate more quickly • have slightly “squashed” shapes • have many moons • have ring systems

10. Inside the Jovian Planets • All Jovian cores appear to be similar. • made of rock, metal, and Hydrogen compounds • 10 x the mass of Earth • Uranus & Neptune captured less gas from the Solar nebula. • accretion of planetesimals took longer • not much time for gas capture before nebula was cleared out by Solar wind • Only Jupiter and Saturn have high enough pressure for H & He to exist in liquid and metallic states.

11. Jovian Storms • We also see high pressure storms • analogous to hurricanes, but they rotate in the opposite direction • Jupiter • the Great Red Spot • we are not sure why it is red • Neptune • the Great Dark Spot

12. The Jovian Atmospheres • The temperature profile of each planet determines the color of its appearance. • Cloud layers form where a particular gas condenses. • Saturn has the same cloud layers as Jupiter. • they form deeper since Saturn is colder overall • they are spread farther apart since Saturn has lower gravity • Uranus & Neptune • cold enough to form methane clouds

13. Jovian Magnetospheres • Saturn, Uranus, & Neptune have smaller & weaker magnetospheres. • fraction of electrically conducting material in interiors is smaller • Solar wind is weaker farther out, or else their magnetospheres would be even smaller • we can not explain the magnetic field tilts of Uranus & Neptune.

14. medium moons 300 to 1,500 km in diameter large moons greater than 1,500 km in diameter both groups formed like planets out of the “mini-Solar nebulae” surrounding the Jovian planets small moons less than 300 km across they are not spherical probably captured asteroids Jovian Planets have Numerous Moons We can divide them into three groups:

15. The moons of Jupiter are listed below by orbital period: 1 XVI Metis 1979 Synnott (Voyager 1) Inner 2 XV Adrastea 1979 Jewitt (Voyager 2) Inner 3 V Amalthea 1892 Barnard Inner 4 XIV Thebe 1979 Synnott (Voyager 1) Inner 5 I Io 1610 Galilei Galilean 6 II Europa 1610 Galilei Galilean 7 III Ganymede 1610 Galilei Galilean 8 IV Callisto 1610 Galilei Galilean 9 XVIII Themisto 1975/2000 Kowal & Roemer/Sheppard et al. 10 XIII Leda 16 1974 KowalHimalia 11 VI Himalia 1904 Perrine Himalia 12 X Lysithea 1938 Nicholson Himalia 13 VII Elara 1905 Perrine Himalia 14 — S/2000 2001 Sheppard et al. Himalia? 15 XLVI Carpo 2003 Sheppard et al. Carpo 16 — S/2003 2003 Sheppard et al. ? 17 XXXIV Euporie 2002 Sheppard et al. Ananke 18 — S/2003 J 3 2003 Sheppard et al. Ananke 19 — S/2003 J 18 2003 Gladman et al. Ananke 20 — S/2011 J 1 2011 Sheppard et al. ? 21 — S/2010 J 2 2010 Veillet Ananke? 22 XLII Thelxinoe 2003 Sheppard et al. Ananke 23 XXXIII Euanthe 2002 Sheppard et al. Ananke

16. 24 XLV Helike ˈhɛlɨkiː 4 0.0090 20540266 −601.40 154.586° 0.1374 2003 Sheppard et al. Ananke 25 XXXV Orthosieɔrˈθɒsɨ.iː 2 0.0015 20567971 −602.62 142.366° 0.2433 2002 Sheppard et al. Ananke 26 XXIV Iocasteaɪ.ɵˈkæstiː 5 0.019 20722566 −609.43 147.248° 0.2874 2001 Sheppard et al. Ananke 27 — S/2003 J 16 2 0.0015 20743779 −610.36 150.769° 0.3184 2003 Gladman et al. Ananke 28 XXVII Praxidikeprækˈsɪdɨkiː 7 0.043 20823948 −613.90 144.205° 0.1840 2001 Sheppard et al. Ananke 29 XXII Harpalykehɑrˈpælɨkiː 4 0.012 21063814 −624.54 147.223° 0.2440 2001 Sheppard et al. Ananke 30 XL Mneme ˈniːmiː 2 0.0015 21129786 −627.48 149.732° 0.3169 2003 Gladman et al. Ananke 31 XXX Hermippehərˈmɪpiː 4 0.0090 21182086 −629.81 151.242° 0.2290 2002 Sheppard et al. Ananke? 32 XXIX Thyoneθaɪˈoʊniː 4 0.0090 21405570 −639.80 147.276° 0.2525 2002 Sheppard et al. Ananke 33 XII Ananke əˈnæŋkiː 28 3.0 21454952 −640.38 151.564° 0.3445 1951 Nicholson Ananke 34 L Herse ˈhɜrsiː 2 0.0015 22134306 −672.75 162.490° 0.2379 2003 Gladman et al. Carme 35 XXXI Aitne ˈaɪtniː 3 0.0045 22285161 −679.64 165.562° 0.3927 2002 Sheppard et al. Carme 36 XXXVII Kale ˈkeɪliː 2 0.0015 22409207 −685.32 165.378° 0.2011 2002 Sheppard et al. Carme 37 XX Taygeteteɪˈɪdʒɨtiː 5 0.016 22438648 −686.67 164.890° 0.3678 2001 Sheppard et al. Carme 38 — S/2003 J 19 2 0.0015 22709061 −699.12 164.727° 0.1961 2003 Gladman et al. Carme 39 XXI Chaldenekælˈdiːniː 4 0.0075 22713444 −699.33 167.070° 0.2916 2001 Sheppard et al. Carme 40 — S/2003 J 15 2 0.0015 22720999 −699.68 141.812° 0.0932 2003 Sheppard et al. Ananke? 41 — S/2003 J 10 2 0.0015 22730813 −700.13 163.813° 0.3438 2003 Sheppard et al. Carme? 42 — S/2003 J 23 2 0.0015 22739654 −700.54 148.849° 0.3930 2004 Sheppard et al. Pasiphae 43 XXV Erinomeɨˈrɪnɵmiː 3 0.0045 22986266 −711.96 163.737° 0.2552 2001 Sheppard et al. Carme 44 XLI Aoedeeɪˈiːdiː 4 0.0090 23044175 −714.66 160.482° 0.6011 2003 Sheppard et al. Pasiphae 45 XLIV Kallichorekəˈlɪkɵriː 2 0.0015 23111823 −717.81 164.605° 0.2041 2003 Sheppard et al. Carme? 46 XXIII Kalyke ˈkælɨkiː 5 0.019 23180773 −721.02 165.505° 0.2139 2001 Sheppard et al. Carme 47 XI Carme ˈkɑrmiː 46 13 23197992 −763.95 165.047° 0.2342 1938 Nicholson Carme

17. 48 XVII Callirrhoekəˈlɪrɵʊiː 9 0.087 23214986 −727.11 139.849° 0.2582 2000 Spahr, Scotti Pasiphae 49 XXXII Eurydomejʊˈrɪdəmiː 3 0.0045 23230858 −723.36 149.324° 0.3769 2002 Sheppard et al. Pasiphae? 50 — S/2011 J 2 1 – 23329710 −725.06 151.8° 0.3867 2011 Sheppard et al. Pasiphae? 51 XXXVIII Pasitheepəˈsɪθɨ.iː 2 0.0015 23307318 −726.93 165.759° 0.3288 2002 Sheppard et al. Carme 52 — S/2010 J 1 2 23314335 −722.83 163.2° 0.320 2010 Jacobson et al. Pasiphae? 53 XLIX Kore ˈkɔəriː 2 0.0015 23345093 −776.02 137.371° 0.1951 2003 Sheppard et al. Pasiphae 54 XLVIII Cyllenesɨˈliːniː 2 0.0015 23396269 −731.10 140.148° 0.4115 2003 Sheppard et al. Pasiphae 55 XLVII Eukeladejuːˈkɛlədiː 4 0.0090 23483694 −735.20 163.996° 0.2828 2003 Sheppard et al. Carme 56 — S/2003 J 4 2 0.0015 23570790 −739.29 147.175° 0.3003 2003 Sheppard et al. Pasiphae 57 VIII Pasiphae pəˈsɪfeɪ.iː 60 30 23609042 −739.80 141.803° 0.3743 1908 Melotte Pasiphae 58 XXXIX Hegemonehɨˈdʒɛməniː 3 0.0045 23702511 −745.50 152.506° 0.4077 2003 Sheppard et al. Pasiphae 59 XLIII Arche ˈɑrkiː 3 0.0045 23717051 −746.19 164.587° 0.1492 2002 Sheppard et al. Carme 60 XXVI Isonoeaɪˈsɒnɵʊiː 4 0.0075 23800647 −750.13 165.127° 0.1775 2001 Sheppard et al. Carme 61 — S/2003 J 9 1 0.00015 23857808 −752.84 164.980° 0.2761 2003 Sheppard et al. Carme 62 — S/2003 J 5 4 0.0090 23973926 −758.34 165.549° 0.3070 2003 Sheppard et al. Carme 63 IX Sinopesɨˈnoʊpiː 38 7.5 24057865 −739.33 153.778° 0.2750 1914 Nicholson Pasiphae 64 XXXVI Sponde ˈspɒndiː 2 0.0015 24252627 −771.60 154.372° 0.4431 2002 Sheppard et al. Pasiphae 65 XXVIII Autonoe ɔːˈtɒnɵʊiː 4 0.0090 24264445 −772.17 151.058° 0.3690 2002 Sheppard et al. Pasiphae 66 XIX Megaclitemɛɡəˈklaɪtiː 5 0.021 24687239 −792.44 150.398° 0.3077 2001 Sheppard et al. Pasiphae — S/2003 J 2 2 0.0015 30290846 −1077.02 153.521° 0.1882 2003 Sheppard et al. ? 39 of 67 moons attributed to Scott Sheppard – a grad student at the IfA!

19. Comparing Jovian Ring Systems • Compared to Saturn, the other ring systems: • have fewer particles • are smaller in extent • have darker particles • Why this is so, we are not sure. • Other unsolved mysteries: • Uranus’ rings are eccentric and slightly tilted from its equatorial plane. • Neptune has partial rings.

22. Saturn’s spectacular rings are composed of fragments of ice and ice-coated rock

23. Moons Pandora and Prometheus act as shepherd moons and keep the F ring to a band about 100km wide because of gravitational effects.

24. Dust spokes in Saturn’s rings

26. A system of rings and satellites revolves around Uranus Uranus sports a hazy atmosphere with few clouds

27. Uranus’ tilt gives it very exaggerated seasons

28. Pluto was discovered in 1930 by Clyde Tombaugh by comparing photographs taken a few days apart.

29. Pluto and its moon, Charon, are about the same size

32. Origin of the Comets • The leftover icy planetesimals are the present-day comets. • Those which were located between the Jovian planets, if not captured, were gravitationally flung in all directions into the Oort cloud. • Those beyond Neptune’s orbit remained in the ecliptic plane in what we call the Kuiper belt. The nebular theory predicted the existence of the Kuiper belt 40 years before it was discovered!

33. The Kuiper Belt of comets spreads from Neptune out 500 AU from the Sun

34. Kuiper Belt Object 1993SC - these images were taken 4.6 hours apart

35. Comet Kohoutek and Comet West

36. Comets lack tails until they enter the inner solar system

37. Comets often have two tails:a thin ION tail and a curving DUST tail

39. Anatomy of a comet

41. Kokoiki –Halley’s comet (1758) Alapaÿi had been warned by his Kahuna Kilo Kilo that a child whose birth would coincide with a celestial display would become the killer of chiefs. Red Aliÿi by Herb Kawainui Kane Alapaÿi feared the prophecy and conspired to kill Kamehameha when this akualele appeared at his birth.

42. 15 km long by 8 km wideComet Halley nucleus

43. Comets don’t last forever Fragmentation of Comet West shortly after passing near the Sun in 1976 (sequence of photos is from March 8 to March 24)

44. Dave Jewitt, Jan Fernandez, and Scott Shepard

45. Comet orbits are altered by gravitational interactions with planets

46. Small rocky debris peppers the solar system • meteors • falling stars • shooting stars • bolides • fireballs each are caused by small rocks colliding with Earth’s atmosphere and heating up due to friction with the air

47. Primary Meteor Showers

50. What have we learned? • What four characteristics of our Solar System must be explained by a formation theory? • Patterns of motion, why there are terrestrial and Jovian planets, why there are asteroids and comets, and why there are exceptions to the rules. • What is the basic idea behind the nebular theory? • Our Solar System formed from a giant, swirling cloud of gas and dust. • What are the exceptions to the nebular theory? • The large size of Earth’s Moon • The extreme tilt of Uranus • Backward orbit of Triton • Venus goes the wrong way