Starry Monday at Otterbein

Astronomy Lecture Series-every first Monday of the month-

June 6, 2005

Dr. Uwe Trittmann

Welcome to

Today’s Topics

• Saturn – the ringed Planet

• The Night Sky in June

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.)

Saturn – the ringed Planet

              

                                                                                                                  

Saturn is a Jovian Planet

Jupiter

Uranus

Saturn

Neptune

Comparison

• 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

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)

Aurora Borealis and Australis on Saturn

Ring Systems

Saturn

Jupiter

Uranus

Neptune

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

Visibility of Saturn’s Rings

Changing Ring Opening

1998

1997

1996

2000

1999

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

Rings and Shepherd Moons

Shepherd moons

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!

Saturn’s Moons

Saturn’s Moons Two-faced looks like Star Wars’ Death Star

We saw these three plus Titan at rooftop

Weitkamp Observatory Picture

• Saturn (March 9, 2004, 20:50 EST) (Photographed with the LX200 10”, and department’s Sony

DSC F-717 Digital Camera)

Saturn’s Moons from

the Roof

Titan• Titan is the only moon in the solar system

known to have an atmosphere

Infrared picture shows surface details

Double-faced Japetus

• Extremely different surface reflectivity

• Probably dust

Space Probes:Voyager & Pioneer

• Pioneer 10 – launched in early 1970ies– Still alive

• Voyagers: launched 1977– Jupiter 1979– Saturn 1981– Uranus 1986– Neptune 1989

The Grand Tour

Smallwindow ofopportunityin 1977

Leaving the Solar System

• Voyager 1– 8.6 billion

miles (95 AU) out

– Speed: 3.6 AU/year

                                                                                                                

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)

• Cassini: NASA space probe•Huygens: ESA lander

Cassini at Saturn: a Picture Harvest

Phoebe –Saturn’s Outpost

A Look through

the Rings

Rhea’s Bright Splat

• Rhea (949 mi)

• Cassini photo from 1.3 million miles

                                                                                

• 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.

                                                                                                   

                                             

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.

                                                                                                                                                                                                 

                                                                                                                            

Surface of Titan

                                                                                                                                                                                                         

                                                                                                                    

                                                                                                                                                                                                    

                                                                                                                         

Titan from 10 km

360° Panorama of Titan

                                                                                                                                                                                                                                  

                                                                                           

                                                                                                                                                                                                         

                                                                                                                    

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.

                         

                          

                               

                    

Titan’s Atmosphere

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

Moon Phases• Today (Waning crescent, 0%)

• 6 / 6 (New Moon)

• 6 / 14 (First Quarter Moon)

• 6 / 22 (Full Moon)

• 6/ 28 (Last Quarter Moon)

Today at

Noon

• Sun at meridian, i.e. exactly south

10 PM Typical

observing hour, early March

• no Moon

• Jupiter past meridian

• Pluto (experts only)

Saturn sets

South-West

Virgo andComa

with the Virgo-Coma

galaxy cluster

Virgo-Coma

Cluster

• Lots of galaxies within a few degrees

M87, M88 and M91

Zenith

• Big Dipper points to the north pole

South– Canes Venatici– Corona Borealis– Bootes– Serpens

Globular Star Clusters:• M 3• M 5• M 13

M 5

Galaxies: • M 51• M 101• M 64 (Bl. Eye)

South-East

– Hercules– Ophiuchus– Serpens

Globular Star Clusters:• M 13• M 92• M 12• M 10 …

M 5Summer is Globular Cluster time!

M13: Globular Cluster

South-East

– Ophiuchus– Serpens– Scorpius

Globular Star Clusters:• M 4• M 19• M 62• M 80 …

M 5Summer is Globular Cluster time!

Summer Break: Mark your Calendars for Fall!

• Next Starry Monday at Otterbein: October 3, 2005, 7 pm (this is a Monday )

• Web pages:– http://www.otterbein.edu/dept/PHYS/weitkamp.asp (Obs.)– http://www.otterbein.edu/dept/PHYS/ (Physics Dept.)

Mark your Calendars II

• Physics Coffee is every Wednesday, 3:30 pm • Open to the public, everyone welcome!• Location: across the hall, Science 256• Free coffee, cookies, etc.

• Will also return in the Fall!