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The
Traveling Exhibit
Science Background
Part B: Meet the Giants
B. Meet The Giants
KEY QUESTIONS:
How do we explore the giant worlds of our
Solar System?
How do the giant worlds compare to Earth?
Let There Be Light
Newton’s Prism
The Electromagnetic Spectrum
Astronomers use light as a tool
Ultraviolet
Visible
Infrared
images in the ultraviolet
show Jupiter's auroral
emissions
What our eyes would
see from a spacecraft or
a distant moon
Bright areas in the
infrared show heat
escaping through gaps in
the clouds
Jupiter at different wavelengths
Giant Worlds are GIANT
Compared to the rocky worlds of the inner Solar System, the giant worlds are
enormous. The largest of them, Jupiter, is so big that more than 10 Earths could line
up across its diameter; more than 1,000 Earths could fit inside; and all the other
planets in the Solar System put together are less than half its tremendous mass. The
other giant worlds are not as big as Jupiter, but they still dwarf rocky planets like
Earth.
Some facts about the Giant Planets
Giant Planets have NO SOLID
SURFACE
You could not land a spaceship on a Giant Planet!
Storm Warnings
The Great Red Spot on Jupiter is 20,000 km
long and has been followed by observers
on Earth since the telescope was invented
400 years ago. This huge storm is made
visible by variations in the composition of
the cloud particles.
Extreme Seasons - Uranus
The Greater a Planet’s Axial
Tilt, the More Extreme its
Seasons
A planet has seasons if its axis
of rotation is tilted relative to its
orbital plane. The tilt causes
the amount of sunlight reaching
the planet to vary from place to
place. Earth’s axis is tilted by
23.5°, producing our familiar
pattern of seasons. By
contrast, Uranus is tilted by
more than 90°, which produces
very extreme seasons indeed.
Wild Weather on Neptune
The Sun at Neptune is 900 times
dimmer than at Earth. Since heat
from the Sun drives weather, the
winds on Neptune should be
relatively mild. Instead, they
whip around at more than 2,000
km per hour. The weather is
correspondingly wild, with
enormous dark storms that come
and go, and high-altitude white
thunderheads that bubble up
from the depths of Neptune’s
thick hydrogen atmosphere.
Heat from Neptune itself may
drive these storms.
Exploring the Giant
Magnetosphere of Jupiter
Fran Bagenal
University of Colorado
Earth
Jupiter's strong
magnetic field
makes a vast
magnetosphere
~100 Jupiter Radii
1000 Suns would fit inside Jupiter's magnetosphere
Earth
Magnetosphere
Solar
Wind
~10 Earth Radii
If you’ve ever seen the beautiful
northern lights on Earth, then
you’ve witnessed visible evidence
of an enormous, invisible
phenomenon: Earth’s magnetic
field. Polar lights, or aurorae,
happen on any planet that has a
magnetic field and an atmosphere.
The glow is caused when charged
particles guided by the magnetic
field collide with atoms in the
atmosphere and stimulate the
emission of light.
Earth Aurorae
Jupiter's 3 Types of Aurora
Steady Main
Auroral Oval
Aurora associated with moons
Variable
Polar Aurora
Saturn also has a large
magnetosphere and
aurorae
All Giant Planets Have Rings
but only Saturn’s are visible
Jupiter
Saturn
Uranus
Neptune
Fun Facts
Planetary rings are not solid. Instead,
they are made of countless ice and
rock fragments, ranging in size from
dust particles to house-sized
boulders.
Saturn’s diameter is more than 9
times that of Earth, and yet its ring
system is only about 50 meters thick!
This means that if Saturn were the
height of a 60-story building, the rings
would be as thin as a sheet of paper.
Rings Up-close
A Cassini image of Saturn. The Sun is behind the
planet, putting Cassini in shadow. Earth is the bright
dot outside the main rings at the ten o’clock
position.
This false-color image of Saturn's main rings was made by
combining data from multiple star occultations using the
Cassini ultraviolet imaging spectrograph. During
occultations, scientists observe the brightness of a star as
the rings pass in front of the star. Cassini has given
scientists the most detailed view yet of Saturn's densely
packed B ring. Particles in the central yellow regions are too
densely packed for any starlight to pass through.
Many Moons
The giant planets each
have many moons ranging
in size from rocky bodies
only a few kilometers
across to one that is larger
than Mercury. New moons
are being found all the
time.
Let’s meet some of them.
Saturn’s Moon Rhea
Europa
An icy moon of Jupiter,
Europa is covered with a
thick layer of ice.
Beneath the ice lies a
massive saltwater ocean
which might harbor life.
Image taken by Voyager 2 spacecraft
Credit: NASA/JPL
Io
This moon of Jupiter is the most
volcanically active body in the
solar system. Eruptions tower
over the surface, as seen here in
this edge-on view of a 90-mile
high plume. The surface of Io is
constantly changing, so no
craters exist today.
Image taken by Voyager 2 spacecraft
Credit: NASA/JPL
Enceladus
An icy moon of Saturn,
Enceladus boasts a myriad of
large fractures – dubbed “tiger
stripes” by the imaging
scientists – that appear to
spout massive geysers of
liquid water, as seen in the
false color image below. Like
Jupiter’s Europa, Enceladus is
now a potential habitat for life
within our Solar System.
Images taken by Cassini spacecraft
Courtesy NASA/JPL/Space Science Institute
Titan
This moon of Saturn,
bigger than the planet
Mercury, boasts a thick,
methane-rich atmosphere,
seen here as the purple
band around the limb. It is
believed that our primordial
Earth had an environment
very similar to Titan’s.
Image taken by Cassini spacecraft,
courtesy NASA/JPL.
B. Meet the Giants
SUMMARY
Jupiter, Saturn, Uranus, and Neptune are mini solar systems. Each
has a collection of many moons and a ring system.
Planetary rings are not solid. Instead, they are made of countless ice
and rock fragments, ranging in size from dust particles to house-sized
boulders.
Each giant planet is surrounded by an enormous magnetic field that is
invisible except near the poles, where magnetized particles show up
as spectacular aurorae.
Our eyes see only a narrow range of the light filling the Universe.
However instruments allow us to detect light waves that are longer or
shorter than our eyes can see. Wavelengths of light reveal
different things about an object such as what it’s made of.
We might be more likely to find life on or in some of the moons of the
giant planets than on any of the terrestrial planets besides Earth.
CONCLUSION
Re-visiting the Big Ideas of the Introductory Presentation
We study the giant planets of our
Solar System because they tell us
about the formation of solar
systems, our planet, and the
conditions necessary for life.
Someday we may answer the ageold question of whether there is
life beyond Earth.
We are developing extraordinary
new tools, techniques, and insights
for exploring these extraordinary
worlds – mini solar systems that
include many moons and
spectacular rings.
There are two
possibilities:
Maybe we’re alone…
Maybe we’re not…
Both are equally amazing…
We shall not cease from exploring,
And the end of all our exploration
Will be to arrive where we started
And to know the place for the first
time.
- T.S. Eliot, Little Gidding