4/15/2015
Today’s Class: The Giant Planets – Saturn & Titan
April 15, 2015
ULA’s New Reusable Rocket: Vulcan
Homework:
1. Reading:
2.
a)
b)
c)
Uranus at http://en.wikipedia.org/wiki/Uranus
Neptune at http://en.wikipedia.org/wiki/Neptune
Mankind Beyond Earth, p. 231-235.
Exam 3 next Wednesday, April 22.
Astronomy 2020 – Space Astronomy & Exploration
Astronomy 2020 – Space Astronomy & Exploration
Last Class
Class Exercise
• Inside Jupiter
– Source of heat
– Magnetosphere
Do you think a human expedition to Europa to
search for life in this moon’s ocean will be
feasible during this century? Why or why not?
• Atmosphere of Jupiter
• The moons of Jupiter
– Io: Active volcanoes
– Europa: Possible ocean & life?
Astronomy 2020 – Space Astronomy & Exploration
Astronomy 2020 – Space Astronomy & Exploration
Today’s Class
Saturn
• Interior of Saturn
• Saturn’s atmosphere & magnetosphere
• Titan
– Atmosphere
– Surface
• Enceladus – water geysers
• The Cassini Mission – results & new goals for
extended mission
Astronomy 2020 – Space Astronomy & Exploration
• Giant and gaseous like Jupiter
• Spectacular rings
• Many moons, including cloudy Titan
Astronomy 2020 – Space Astronomy & Exploration
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4/15/2015
Saturn
• Rings are NOT solid;
they are made of
countless small
chunks of ice and
rock, each orbiting
like a tiny moon.
Ring Formation
• Jovian planets all have rings because they possess many small
moons close in.
• Impacts on these moons are random.
• Saturn's incredible rings may be an "accident" of our time.
Astronomy 2020 – Space Astronomy & Exploration
Astronomy 2020 – Space Astronomy & Exploration
Comparing Jovian Interiors
Jovian Planet Atmospheres
• Other jovian planets
have cloud layers
similar to Jupiter's.
• Models suggest cores of jovian planets have
similar composition.
• Lower pressures inside Uranus and Neptune
mean no metallic hydrogen.
• Different compounds
make clouds of
different colors.
Astronomy 2020 – Space Astronomy & Exploration
Astronomy 2020 – Space Astronomy & Exploration
Saturn's Colors
Other Magnetospheres
• All jovian planets
have substantial
magnetospheres,
but Jupiter's is the
largest by far.
• Saturn's layers are similar, but deeper in and
farther from the Sun (more subdued).
Astronomy 2020 – Space Astronomy & Exploration
Astronomy 2020 – Space Astronomy & Exploration
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4/15/2015
Medium and Large Moons
Titan's Atmosphere
• Titan is the only
moon in the solar
system to have a
thick atmosphere.
• Enough self-gravity to
be spherical
• Have substantial
amounts of ice
• Formed in orbit around
jovian planets
• Circular orbits in same
direction as planet
rotation
• It consists mostly
of nitrogen with
some argon,
methane, and
ethane.
Astronomy 2020 – Space Astronomy & Exploration
Astronomy 2020 – Space Astronomy & Exploration
Titan's Surface
Medium Moons of Saturn
• Huygens probe provided first look at Titan's
surface in early 2005.
• It found liquid methane and "rocks" made of ice.
• Almost all of them show evidence of past
volcanism and/or tectonics.
Astronomy 2020 – Space Astronomy & Exploration
Astronomy 2020 – Space Astronomy & Exploration
Enceladus – Geysers of Water
Medium Moons of Saturn
• Ice fountains of
Enceladus suggest it
may have a
subsurface ocean.
Astronomy 2020 – Space Astronomy & Exploration
• Iapetus has a
curious ridge
around much of
its equator
Astronomy 2020 – Space Astronomy & Exploration
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4/15/2015
Cassini at Saturn/Titan
The Cassini Mission
Cassini probe arrived July 2004 (launched in 1997).
• Now on an extended
mission through Sep.
2017.
video
Surface of Titan
Astronomy 2020 – Space Astronomy & Exploration
Astronomy 2020 – Space Astronomy & Exploration
Goals for Cassini Extended Mission
•
•
•
•
•
Enceladus - Small, icy Enceladus is surprisingly active. Tidal heating is keeping Enceladus
warm, and hotspots associated with the fountains have been pinpointed. With heat, organic
chemicals and, potentially liquid water, Enceladus could be a place where primitive life forms
might evolve.
Titan - During the earlier parts of the mission, Cassini investigated the structure and complex
organic chemistry of Titan's thick, smog-filled atmosphere. The Huygens probe revealed vast
methane lakes & wind-sculpted hydrocarbon sand dunes. Cassini also deduced the presence
of internal, liquid water-ammonia ocean. Cassini will look for signs of seasonal climate
change such as storms, flooding, or changes in lake levels, as well as evidence of volcanic
activity.
Saturn - The spacecraft eventually will make repeated dives between Saturn and its rings to
obtain in depth knowledge of the gas giant. Spacecraft will study the internal structure of
Saturn, its magnetic fluctuations, and the mass of the rings.
Rings - From a distance the rings look ordered and tidy. But up close, Cassini finds Saturn’s
rings to be a complex place where small moons and ring particles jostle and collide, where
waves and jets constantly form and dissipate.
Magnetic Environment - One major discovery was that water ice jets from Enceladus play a
major role in Saturn’s magnetosphere. Water from the jets loads up the magnetosphere,
influencing radio and auroral activity. Cassini will study these phenomena & probe for links
to Enceladus in addition to connections with other moons.
Astronomy 2020 – Space Astronomy & Exploration
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