1. Starry Monday at Otterbein Astronomy Lecture Series -every first Monday of the month- October 5, 2010 Dr. Uwe Trittmann Welcome to

2. Today’s Topics Close Encounter with Jupiter The Night Sky in October

3. Observing Planets Inner Planets: closer to sun than Earth –Mercury & Venus –Always close to sun in the sky Outer Planets: further from sun than Earth –Mars, Jupiter, Saturn, Uranus, Neptune, Pluto –Best viewing when opposite of sun in the sky

4. Inner Planets Inner planet Earth superior conjunction inferior conjunction western elongation eastern elongation

5. Outer Planets Outer planet Earth conjunction opposition quadrature

6. Close Outer Planet (Mars) Outer planet Earth Size of planet varies a lot as Earth moves

7. Far-Out Planet (e.g. Jupiter) Outer planet Earth Size of planet varies little as Earth moves

8. Jupiter Color: yellowish-white Brightness: up to –2.9m Size: up to 50” When to observe: most of the year, except for some months around conjunction Difficulty: easy, moons visible in binoculars

9. Jupiter & Moons

10. General Features of Jupiter Largest planet Low density –Primarily ball of light gases compressed by gravity Fastest rotation No seasons Has Rings 63 Moons 1/1000 mass of sun, 320x Earth

11. Jupiter’s Orbit Average distance from Sun: 779 mill. km = 5.2 A.U. Eccentricity: 0.0488 Closest to Sun: 741 mill. km Farthest from Sun: 817 mill. km Jupiter Year = 11.86 Earth years

12. Kepler’s First Law The orbits of the planets are ellipses, with the Sun at one focus

13. Ellipses a = “semimajor axis”; e = “eccentricity”

14. Kepler’s Second Law An imaginary line connecting the Sun to any planet sweeps out equal areas of the ellipse in equal times

15. Kepler’s Third Law The square of a planet’s orbital period is proportional to the cube of its orbital semi-major axis: P 2  a 3 a P Planet Orbital Semi-Major AxisOrbital Period Eccentricity P 2 /a 3 Mercury0.387 0.241 0.2061.002 Venus0.723 0.615 0.0071.001 Earth1.000 1.000 0.0171.000 Mars1.524 1.881 0.0931.000 Jupiter5.203 11.86 0.0480.999 Saturn9.539 29.46 0.0561.000 Uranus19.19 84.01 0.0460.999 Neptune30.06 164.8 0.0101.000 Pluto39.53 248.6 0.2481.001 (A.U.)(Earth years)

16. Jupiter Opposition 2010 Best since 1951, until 2022 Distance: 3.9539 AU unexpected disappearance of Jupiter's South Equatorial Belt (SEB) earlier this year SEB’s return is often impressive, with dramatic storms erupting suddenly. Days or years before Jupiter looks normal again

17. Jupiter’s Atmosphere Cloud bands parallel to equator Great Red Spot –First observed in 1664 by Robert Hooke

18. Jupiter’s Atmosphere 86% Hydrogen, 14% Helium; some methane, water, ammonia Several layers of clouds: ammonia, ammonium hydrosulfide, water Colors mostly due to compounds of sulfur and phosphorus

19. Great Red Spot About twice the diameter of the Earth A hurricane that is hundreds of years old!

20. GRS As seen by Voyager 1, 1979

21. Jupiters’ Bands: Zones and Belts Belts: cool, dark, sinking Zones: warm, bright, rising Jovian weather mostly circles the planet due to high rotation rate Bands exhibit east–west flow  Great Red Spot lies between regions of opposite wind flow

22. Naming of Belts & Zones Tropical, equatorial, temperate Zone/Belt

23. Jupiter Changes

24. Missing Belt!

25. Rotation About 9 hours for Jupiter and Saturn Differential rotation: rotation speed varies from point to point on the “surfaces” –Gaseous bodies with no solid surfaces! –On Jupiter, the equatorial regions rotate 6 minutes slower than polar regions Flattening of planet! Tilt of rotation axis: –almost none – no seasons!

26. 4 Galilean Moons + 59 others

27. 4 Moons are Planet Size

28. Jupiter’s Galilean Moons

29. Io Jupiter’s innermost moon Size and mass similar to our moon Zips around Jupiter in just 2 days

30. Io The most volcanically active object in the solar system –Heated by tidal friction Eruptions as high as 200 miles, may last for months

32. Europa Europa might have liquid water oceans under the surface  Life?

33. Ganymede Largest Moon in the solar system: 5260km diameter Icy surface, dark parts are oldest

34. View through the Telescope

35. Comet Shoemaker-Levy 9 HST image (1994); Earth added to show scale

36. Comet Shoemaker-Levy 9 Headed for Jupiter…

37. Impact on Jupiter

38. Space Probes Pioneer –Jupiter and Saturn; early 70's –First man-made object to leave solar system Voyager –“Grand Tour” of Jupiter, Saturn, Uranus and Neptune –Launched 1977; arrived 1979 Galileo –Launched in 1989 on space shuttle –Boosted by gravitational assists from Earth and Venus –Two-part spacecraft arrived late 1995 Atmospheric probe entered Jupiter's atmosphere 12/7/95 Orbiter the first permanent orbiter of outer planets Cassini - arrived at Saturn 2004, Huygens probes Titan right now

39. Internal Structure Gas of increasing density and pressure On Jupiter and Saturn, conditions are such that hydrogen becomes metallic; dense cores Uranus and Neptune probably have conducting slushy layers

40. Magnetospheres Very strong – Jupiter's extends past the orbit of Saturn! Indicate the presence of conducting cores

41. The Night Sky in October The sun is past autumn equinox -> longer nights! Autumn constellations are coming up: Cassiopeia, Pegasus, Perseus, Andromeda, Pisces  lots of open star clusters! Jupiter is visible most of the night

42. Moon Phases Today (Waning Crescent) 10 / 7 (New Moon) 10/ 14 (First Quarter Moon) 10 / 22 (Full Moon) 10/ 30 (Last Quarter)

43. Today at Noon Sun at meridian, i.e. exactly south

44. 10 PM Typical observing hour, early October Uranus Neptune Jupiter

45. South- West High in the sky: The summer triangle

46. Due North Big Dipper points to the north pole

47. High up – the Autumn Constellations W of Cassiopeia Big Square of Pegasus Andromeda Galaxy

48. “PR” Foto Actual look

49. East Perseus and Auriga with Plejades and the Double Cluster

50. Greek Mytho- logy in the Sky

51. South - 2006 Planets –Uranus –Neptune Zodiac: –Capricorn –Aquarius

52. South – 2007 Planets –Uranus –Neptune Zodiac: –Capricorn –Aquarius

53. South – 2008 Planets –Uranus –Neptune Zodiac: –Capricorn –Aquarius

54. South – 2009 Planets –Uranus –Neptune Zodiac: –Capricorn –Aquarius

55. South – 2010 Planets –Uranus –Neptune Zodiac: –Capricorn –Aquarius

56. Mark your Calendars! Next Starry Monday: November 1, 2010, 7 pm (this is a Monday ) Web pages: –http://www.otterbein.edu/dept/PHYS/weitkamp.asp (Obs.)http://www.otterbein.edu/dept/PHYS/weitkamp.asp –http://www.otterbein.edu/dept/PHYS/ (Physics Dept.)http://www.otterbein.edu/dept/PHYS/