1. Welcome to Starry Monday at Otterbein Astronomy Lecture Series -every first Monday of the month- June 6, 2005 Dr. Uwe Trittmann

2. Today’s Topics • Saturn – the ringed Planet • The Night Sky in June

3. Feedback! • Please write down suggestions/your interests on the note pads provided • If you would like to hear from us, please leave your email / address • To learn more about astronomy and physics at Otterbein, please visit • http://www.otterbein.edu/dept/PHYS/weitkamp.asp (Obs.) • http://www.otterbein.edu/dept/PHYS/ (Physics Dept.)

4. Saturn – the ringed Planet

5. Saturn Jupiter Neptune Uranus Saturn is a Jovian Planet

6. Terrestrial close to the Sun closely spaced orbits small radii small masses predominantly rocky high density solid surface few moons no rings Jovian far from the Sun widely spaced orbits large radii large masses predominantly gaseous low density no solid surface many moons many rings Comparison

7. Saturn’s Atmosphere • 92% Hydrogen 7% Helium; some methane, water, ammonia • Belt structure similar to Jupiter’s, but fainter • Storms are rarer • White spot seen, 1990 (Voyager)

8. Aurora Borealis and Australis on Saturn

9. Ring Systems Saturn Uranus Neptune Jupiter

10. Saturn’s Rings • Rings composed of small, icy fragments, orbiting in concentric circles • James Clerk Maxwell; confirmed by James Keeler (1895) using Doppler shift • Orbits obey Kepler’s laws (of course!) • Inner rings move faster than outer ones

11. Visibility of Saturn’s Rings

12. Changing Ring Opening 2000 1999 1998 1997 1996

13. How Do They Form? • Miscellaneous debris • Moons or other small bodies torn apart by tidal forces • Roche limit – distance inside of which an object held together by gravity will be pulled apart

14. Rings and Shepherd Moons Shepherd moons

15. Ring Formation • Rings may be short lived (on the time scale of solar system) • Means that they must form fairly frequently • A moon may pass too close to a planet (within the Roche limit) and be destroyed by tidal forces • This will probably happen to Triton (a moon of Neptune) within 100 million years!

16. Saturn’s Moons

17. Saturn’s Moons Two-facedlooks like Star Wars’ Death Star We saw these three plus Titan at rooftop

18. Weitkamp Observatory Picture • Saturn (March 9, 2004, 20:50 EST) (Photographed with the LX200 10”, and department’s Sony DSC F-717 Digital Camera)

19. Saturn’s Moons from the Roof

20. Titan • Titan is the only moon in the solar system known to have an atmosphere Infrared picture shows surface details

21. Double-faced Japetus • Extremely different surface reflectivity • Probably dust

22. Space Probes:Voyager & Pioneer • Pioneer 10 • launched in early 1970ies • Still alive • Voyagers: launched 1977 • Jupiter 1979 • Saturn 1981 • Uranus 1986 • Neptune 1989

23. The Grand Tour Small window of opportunity in 1977

24. Leaving the Solar System • Voyager 1 • 8.6 billion miles (95 AU) out • Speed: 3.6 AU/year

25. The Sounds of Earth – Message to the Aliens • On the chance that someone is out there, NASA approved the placement of a phonograph record on each of the Voyager spacecraft. The recording, called "Sounds of Earth" fits on a 12-inch, copper disc containing greetings from Earth people in 60 languages, samples of music from different cultures and eras, and natural sounds of surf, wind and thunder, and birds, whales and other animals. The record also contains electronic information that an advanced technological civilization could convert into diagrams, pictures and printed words, including a message from President Carter. (Courtesy NASA)

26. Cassini: NASA space probe • Huygens: ESA lander

27. Cassini at Saturn: a Picture Harvest

28. Phoebe –Saturn’s Outpost

29. A Look through the Rings

30. Rhea’s Bright Splat • Rhea (949 mi) • Cassini photo from 1.3 million miles

31. Visible here are: Mimas (397 kilometers, or 247 miles across) near lower right; Janus (181 kilometers, or 113 miles across) below the F ring; and Enceladus (505 kilometers, or 314 miles across) at lower left.

32. Hyugens at Titan • STRANGE TITAN: Get ready for two of the strangest hours in the history of space exploration. That's how long it will take the European Space Agency's Huygens probe to parachute to the surface of Saturn's largest moon Titan on January 14th, 2005. Huygens will sample Titan's atmosphere, photograph its bizarre terrain, listen for alien sounds and, possibly, splash down in a liquid methane sea.

33. Surface of Titan

35. Titan from 10 km

36. 360° Panorama of Titan

38. Titan’s thick atmosphere • made up of nitrogen and methane • extremely cold -290 degrees Fahrenheit • Scientists believe Titan's atmosphere may be similar to that of the primordial Earth and studying it could provide clues to how life began.

39. Titan’s Atmosphere

40. The Night Sky in June • The sun is at its highest -> shortest nights! • Summer constellations are coming up: Hercules, Scorpius, Ophiuchus (Snake Bearer), Snake  lots of globular star clusters! • Center of the Milky Way in Sagittarius • Jupiter is in the South at sunset

41. Moon Phases • Today (Waning crescent, 0%) • 6 / 6 (New Moon) • 6 / 14 (First Quarter Moon) • 6 / 22 (Full Moon) • 6/ 28 (Last Quarter Moon)

42. Today at Noon • Sun at meridian, i.e. exactly south

43. Saturn sets 10 PM Typical observing hour, early March • no Moon • Jupiter past meridian • Pluto (experts only)

44. South-West Virgo and Coma with the Virgo-Coma galaxy cluster

45. Virgo-Coma Cluster • Lots of galaxies within a few degrees

46. M87, M88 and M91

47. Zenith • Big Dipper points to the north pole

48. South • Canes Venatici • Corona Borealis • Bootes • Serpens • Globular Star • Clusters: • M 3 • M 5 • M 13 • Galaxies: • M 51 • M 101 • M 64 (Bl. Eye) M 5

49. South-East • Hercules • Ophiuchus • Serpens • Globular Star • Clusters: • M 13 • M 92 • M 12 • M 10 … Summer is Globular Cluster time! M 5

50. M13: Globular Cluster