Cassini Celebration
LASP, University of Colorado
30 June 2004
Saturn - the Big Picture
Nick Schneider, LASP/APS
What is Saturn like?
Why is Saturn so different from Earth?
Why so many moons, and why so interesting?
Why does Saturn have rings?
Saturn
• Giant and gaseous like Jupiter
• most spectacular rings of the 4 jovian planets
• many moons, including cloud-covered Titan
Jovian Planets A Different Kind of Planet
•
•
•
•
Bigger & more massive
Lower density, different composition
Rings
Numerous moons
Terrestrial planets are small, rocky, and close to the Sun.
Jovian planets are large, gas-rich, and far from the Sun.
Inside Saturn…
What’s it like inside Saturn?
Why is Saturn so different from Earth?
Our solar system
started as a cloud
like this…
The cloud of gas that gave birth to our solar system
resulted from the recycling of gas through many
generations of stars within our galaxy.
A collapsing cloud forms
the solar system…
Why are there two types of planet, when all
planets formed from the same nebula?
Fig 9.5
Inside the frost line: too hot for hydrogen compounds to form ices.
Outside the frost line: cold enough for ices to form.
Jovian planets create their own swirling clouds…
Why is Saturn different from Earth?
•
•
Outer planets get bigger because
abundant hydrogen compounds
condense to form ICES.
Outer planets accrete and keep
abundant hydrogen & helium gas gas
because they’re bigger.
Why so many moons,
…and why so interesting?
Saturn’s
moons 31 and counting
What kind of moons orbit the
jovian planets?
• Lots of moons mostly formed at the
same time as their planets from the
swirling cloud surrounding Saturn.
• Small moons are mostly captured
asteroids and comets.
One small
moon…
What makes Titan different from
other moons?
• only moon with a thick
atmosphere
• may also have surface
lakes of methane and
ethane
• ‘organic goop’ is ‘the
stuff of life’
• -Cassini movie-
Titan’s smoggy atmosphere
• 90% nitrogen, plus
argon, methane,
ethane, other
hydrogen
compounds.
• Methane & ethane
are greenhouse
gases.
• Still cold: 93 K
(-180 degrees C)
Why does Saturn have rings?
Spacecraft view
Rings are NOT
solid; they are
made of
countless small
chunks of ice
and rock, each
orbiting like a
tiny moon.
Artist’s conception
Saturn - the Big Picture
Nick Schneider, LASP/APS
What is Saturn like?
Why is Saturn so different from Earth?
Why so many moons, and why so interesting?
Why does Saturn have rings?
Got the Saturn Bug?
• http://saturn.jpl.nasa.gov - Cassini Mission web site
• http://ciclops.org - Imaging Team web site
• http://boulderastro.org/ Boulder Astronomy & Space Society
• http://longmontastro.org/ Longmont Astronomical Society
• Friday Night Open House at Sommers Bausch Observatory
• Planetary Science classes at CU!