Download Seeing Saturn Cart

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Seeing Saturn Cart
Brief Summary
This cart and its props illustrate three different ways that people have recorded images of
Saturn, 1) as a simple drawing, 2) as photographs seen from Earth and 3) from spacecraft that
have flown near Saturn. The Seeing Saturn Cart allows visitors to wander around the cart and
see these three views of Saturn.
Equipment Required
Seeing Saturn Cart
Fig 1- Seeing Saturn Cart
Fig 2 – Front display. Notice
the hole that serves as
simulated telescope view
Fig 3 – Rear Display
Fig 4 0 Close up of the
wheel that turns
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Main Teaching Points
The purpose of the Seeing Saturn Cart is:
1) To demonstrate how the view of Saturn and its rings from Earth changes as Saturn
orbits the Sun.
2) To talk about the history of the discovery and understanding of Saturn’s rings
3) To allow visitors to explore the variety of 2-dimensional shadows made by a single 3
dimensional object, which is similar to what early observers saw with their basic
telescopes.
Educational Strategy
This model provides the opportunity to discuss the 17th Century “Mystery of Saturn’s Rings.”
To early observers, the rings seemed to disappear at regular intervals. Solving mysteries is
always a crowd pleaser. In addition, the issue of what you see when you shift perspectives is
a crucial one to science.
Set Up
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The Seeing Saturn Cart is located by the Experiment on the lower level of Space
Odyssey. It is plugged into a timer that has it automatically come on during regular
Museum hours.
Suggested ways of presenting demo
Try this approach, which treats the demo as a guessing game:
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Suggest that the visitors look at the painted Saturn ball from different views, noticing
the tilt of the rings.
Have visitors look at the historical drawings of Saturn drawn by Galileo, Huygens
and Cassini, and have them speculate why they would have seen Saturn that way.
Show visitors the view of Saturn on the rear display (shadows), which would be
similar to what early observers would have viewed through their basic telescopes
After visitors have explored on their own, have them look through the simulated
telescope hole on the front of the cart.
Turn the Saturn wheel so that visitors can see the apparent change in the slant of
the rings.
Have visitors make suggestions as to the cause. Explain to visitors that SATURN
DOES NOT CHANGE ITS RING ORIENTATION AS IT ORBITS THE SUN. The
apparent change in the tilt of the rings is due entirely to how our view of it from Earth
changes as Saturn orbits the Sun. Thus, over the Saturnian year (30 Earth years),
the rings appear to precess. To pass from one extreme where the rings appear
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mostly open (such as the view Galileo drew) to the edge-on view (when the rings
seem to disappear) takes about one quarter of a Saturn year, or 7.5 years.
In one could view Saturn from a point outside of our solar system, , Saturn’s rings
would always maintain their same orientation of 25 degrees from the Solar system’s
North Pole, which is the same as Saturn’s axial tilt.
Other Cool Stuff to Try
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Take interested visitors to the ORBITS TABLE or to the wall mounted pictures of Saturn
near the Planetarium entrance.
Using the MGG Portal, show visitors the latest Cassini Mission updates
Use Starry Night Pro (SNP) or the Orbits Table to show the 60 plus moon of Saturn we now
know of.
Use SNP top show how to find Saturn tonight.
Operating Tips
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If you wish to move the cart, unplug the cart from the wall in front of the Mars Diorama.
Make sure you have access to an electrical outlet near where you would like to facilitate
it so that the cart has power.
A Quick History of Understanding Saturn’s Rings
1610
1612
1655
1660
1676
1883
1979
1980 & 1981
2004
Galileo discovers Saturn’s rings
Galileo notices that rings have disappeared
Huygens conjectures that Saturn is surrounded by a solid ring
Chapelain suggest rings made up of many small bodies
Cassini discovers a gap in the rings of Saturn
First photographs of Saturn’s rings
Pioneer 11 Spacecraft flies by Saturn’s and takes first close-up pictures
Voyage 1 & 2 Spacecraft flies by Saturn and photographs Saturn & its moons
Cassini Spacecraft orbits Saturn and drops Huygens probe onto Titan.
Cassini's mission is slated to continue through September 2017
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Saturn Fast Facts
SATURN DAY
SATURN YEAR
SIZE
DISTANCE TO SUN
ORBITAL
ECCENTRICITY
DENSITY
COMPOSITION
ATMOSPHERE
REFLECTANCE
Saturn rotates on its axis every 10.2 hours.
Saturn rotates on its axis every 29.5 yr. It takes Saturn over two years
to cross through any constellation of the zodiac. This makes it easy
to find at night.
120,660 km = 9.5 times Earth
9.5 AU = 880 million miles from the Sun. This means that the Sun
seen from Saturn is only about 1.1% as large in area as the Sun is
from Earth.
Saturn = 0.056; (Earth = 0.017; Mars = 0.093) The practical effect is
that when Saturn is at the elongated part of its orbit (aphelion) is not
as bright to viewers on Earth. Saturn is brighter at it is perihelion.
0.69 g/ml. This is below the density of water, so Saturn would float on
water!
rocky core, a liquid metallic hydrogen layer and a molecular hydrogen
layer
Mainly hydrogen and helium gas
Visual albedo = 0.46 (Earth’s moon = 0.11)
Source: The Nine Planets @ http://www.nineplanets.org/saturn.html
Cassini-Huygens Probe
Launch date
Saturn arrival date
Launch mass
Total flight path
Power source
Communications:
Huygens probe release date
Oct 15, 1997
July 1, 2004
5,574 kilograms (6.1 tons)
5 billion kilometers (3 billion, 200 million miles)
700 watts of electrical power comes from three radioisotope
thermoelectric generators
three antennas, operating at microwave frequency. The large
white dish on Cassini is the 2-way high-gain antenna
November 6, 2004, landed on Titan January 14, 2005
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The Cassini orbiter has:
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Examined the gravitational field of Saturn, its rings and moons using radio waves
Take photos in visible, near-ultraviolet (UV) and near-infrared (IR) light
Mapped the surface of Titan using radar
Has studied particles around Saturn and its rings and flown by its moons to learn about
their atmospheres and ionospheres
Study ice and dust grains in the Saturn system
Cassini continues to operate in orbit around Saturn and its moons in 2015 and is likely
to continue its mission into 2017
The Huygens probe, contributed by the European Space Agency successfully landed on Titan
and:
 Took pictures of Titan's atmosphere and surface
 Studied clouds, chemical composition, winds and particles in Titan's atmosphere
 Explored the surface of Titan immediately adjacent to the landing site
Questions and Answers
Are the rings solid?
Though they look continuous from the Earth, the rings are actually composed of innumerable
small particles each in an independent orbit. They range in size from a grain of sugar, to the
size of a house and everything in between.
How thick are the rings?
Saturn's rings are extraordinarily thin: though they're up to 175,000 miles in diameter they are
only 30 feet thick. Despite their impressive appearance, there's really very little material in the
rings -- if the rings were compressed into a single solid object it would be no more than 62 miles
across.
What are the rings made of?
The ring particles are made of water ice as well as some small rocky particles that are coated
in ice.
How did the rings form?
While the exact origin of the rings of Saturn (and the other Jovian planets) is not known, it is
thought that Saturn’s rings were probably formed by comets, asteroids, or moons that were
pulled into orbit and broken up by Saturn’s strong gravity. As the pieces of these objects
continued to orbit Saturn, they collided; creating even smaller pieces that eventually became
more evenly distributed and formed the rings. However, the rings are not stable and must be
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regenerated by an ongoing process. Enceladus, a moon of Saturn, has geysers of water that
may be part of this regeneration process.
All we see of Saturn is clouds. Is there a solid planet under the clouds?
Saturn's deep interior is similar to Jupiter's consisting of a rocky core, a liquid metallic hydrogen
layer and a molecular hydrogen layer. Traces of various ices (water ice is very familiar on Earth,
but, methane, and ammonia can also form solids at extremely low temperatures.) Saturn's
interior is hot (12000 K at the core) and Saturn radiates more energy into space than it receives
from the Sun. Most of the extra energy is generated by the slow gravitational compression of
the planet as in Jupiter. But this may not be sufficient to explain Saturn's luminosity; some
additional mechanism may be at work, perhaps the "raining out" of helium deep in Saturn's
interior.
What are Saturn’s clouds made of?
Like Jupiter, Saturn is about 75% hydrogen and 25% helium with traces of water, methane,
ammonia and "rock", similar to the composition of the primordial Solar Nebula from which the
solar system was formed. Winds in the upper atmosphere of Saturn reach up to 1600 feet per
second. These super-fast winds, along with heat rising from the core cause the yellow and gold
bands visible in the atmosphere.
Where did we get our information about Saturn’s clouds?
Details in the cloud tops are invisible from Earth so it was not until the Voyager encounters that
any detail of Saturn's atmospheric circulation could be studied. Saturn also exhibits long-lived
oval and other features common on Jupiter. In 1990, the Hubble Space Telescope observed
an enormous white cloud near Saturn's equator which was not present during the Voyager
encounters; in 1994 another, smaller storm was observed. Over the course of its mission,
Cassini has observed several storms on Saturn, including one in 2010 that was called a
“monster storm” because of its intensity and long-lived turbulence. Findings from the Cassini
mission revealed the dynamics of Saturn’s storms. The storms on Saturn are similar to
convective storms on earth that send air and water vapor high into the atmosphere, creating
tall billowing clouds that can be 10-20 times larger than thunder clouds on Earth.
Are the rings connected?
Two prominent rings (A and B) and one faint ring (C) can be seen from the Earth. The gap
between the A and B rings is known as the Cassini division. The much fainter gap in the outer
part of the A ring is known as the Encke Division (but this is somewhat of a misnomer since it
was very likely never seen by Encke). Using Voyager and Cassini, scientists have found an
additional five rings. Some gaps in the rings have moons inside of them (Encke and Keller
gaps). These tiny moons keep the gaps between rings open. Saturn's rings, unlike the rings of
the other planets, are very bright (albedo 0.2 - 0.6). (Albedo is the fraction of incident light that
is reflected.)
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What are some of the unsolved issues about Saturn?
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How does Saturn generate its internal heat?
What is the origin of the rings? What does that tell us about the origin of the solar system
as a whole? Why are Saturn's rings so much more dramatic than the other gas giants?
Source: The Nine Planets @ http://www.nineplanets.org/saturn.html and The Cassini Mission @ saturn.jpl.nasa.gov
Potential Problems
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If moving the cart to a different location, make sure you have an outlet in that location to
plug-in the cart.
Background materials
collections links)
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(websites,
videos,
articles,
digital
http://www.solarviews.com/eng/saturnbg.htm - Historical Background of Saturn’s rings
(with diagrams)
http://solarsystem.nasa.gov/planets/profile.cfm?Object=Saturn
http://www.nineplanets.org/saturn.html - Great Saturn Factsheet
http://www.solarviews.com/eng/saturn.htm - Another good Saturn Factsheet
http://saturn.jpl.nasa.gov/index.cfm - Cassini-Huygens home page
http://saturn.jpl.nasa.gov/kids/index.cfm - Cassini Mission Kid’s Page
http://sci.esa.int/cassini-huygens/ -- ESA Cassini-Huygens home page