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Chapter 7: The Jovian Planets
Jupiter and Saturn
Jupiter and Saturn are the two largest and best known
Jovian planets. Others include Uranus and Neptune. Pluto
is considered as a separate object.
Great
Red
Spot
a) Earth Based View
b)View from Hubble
The four brightest moons are called the Galilean satellites after Galileo
Chapter 7: The Jovian Planets
While Jupiter is known for its four brightest moons and the
red spot, Saturn is known for its extensive ring system.
a) Earth Based View
b)View from Hubble
Chapter 7: The Jovian Planets
Discovery of Uranus
Uranus was discovered by William Herschel while cataloging stars.
Uranus slowly moved among the stars proving it was a planet.
Herschel wanted to name the planet “George” but was talked into
Uranus by Johann Bode.
a) Earth view
b) Voyager 2 view
Chapter 7: The Jovian Planets
Discovery of Neptune
a) Earth view
The orbit of Uranus was
being gravitationally
perturbed by another
unknown planet. After
two years of searching,
they found the planet
within 2 degrees of its
predicted position.
a) Voyager 2 view
Chapter 7: The Jovian Planets
Physical Properties
Notice for example that Jupiter is 315 times more massive than
the Earth and 11 times bigger while being less dense.
Chapter 7: The Jovian Planets
It is difficult to measure the rotation rates of the Jovian planets
because they have no “surface” to watch as they rotate.
With nothing to tie them down different parts of the atmosphere
rotate at different speeds (differential rotation).
The Jovian planets are also
known as the gas giants.
Chapter 7: The Jovian Planets
Jupiter’s Atmosphere
Because of its high escape velocity, Jupiter has been able to retain
all the lighter gasses including hydrogen and has the same
chemical proportions as when it was created 4.6 billion years ago.
It consists of 86% hydrogen, 14% helium, traces of methane,
ammonia, and water vapor.
After its four bright moons, Jupiter is
best known for its cloud bans.
The bands are the result of convection
currents in the atmosphere. Lighter
warmer gasses tend to ride on top
(ammonia) and the cooler heavier gasses
sink down (ammonium hydrosulfide)
giving a light/dark pattern on the
surface.
Chapter 7: The Jovian Planets
Weather on Jupiter
In addition to the large scale band structures on Jupiter there are
smaller structures. The most famous being the great red spot
which is a hurricane storm which has been raging for over 300
years. Spacecraft have detected lightening and aurora.
Show Fix laser disk video:
side 2, at 15559
Chapter 7: The Jovian Planets
Saturn’s Atmosphere
Saturn is not as colorful or turbulent as Jupiter. This may be
due to the fact that Saturn is cooler because it is further away
from the Sun.
It does not contain as large of storms not are they permanete.
It also has enough gravity to hold on to all the gasses and
consists of 92.4% hydrogen, 7.4 helium, and traces of
methane and ammonium
The most famous thing about Saturn is its rings.
Chapter 7: The Jovian Planets
“Real” color
Color enhanced
to show structure.
Chapter 7: The Jovian Planets
Some storms on Saturn actually encircle the planet.
Sequence of images from Hubble