Download The Jovian Planets

Chapter 7
The Jovian Planets
Jupiter from Spacecraft Cassini
Figure 7.1
Jupiter a) earth based telescope, b) HST
Figure 7.2
Saturn from HST
Spacecraft Jovian Exploration
• Gravity assist
• Voyager 1 & 2
• Galileo
• Cassini-Huygens
More Precisely 7-1
Gravitational “Slingshots”
Voyager 1 & 2 spacecraft
• Launched 1977
• Reached Jupiter 1979
• Used gravity assist
• 1 reached Saturn 1980
• 2 reached Saturn 1981
• 2 reached Uranus 1986
• 2 reached Neptune 1989
More Precisely 7-1
Gravitational “Slingshots”
Galileo spacecraft
• Launched 1989
• Three gravity assists through inner solar
system
• Reached Jupiter December 1995
• Probe entered Jupiter’s atmosphere
• Orbiter studied Jupiter’s moons
Figure 7.10
Galileo’s Atmospheric Probe Entry Site
Figure 7.3
Jupiter from Cassini (on way to Saturn)
Cassini-Huygens spacecraft
• Launched October 1997
• Reached Saturn July 2004
• Cassini - orbiter and Huygens - probe
• Huygens entered Titan’s atmosphere
January 2005
Figure 7.4
Uranus from Voyager 2
Uranus
• Discovered by William Herschel in 1781
• Barely visible to naked eye
• Orbit not exactly elliptical
• Another planet influencing it
Figure 7.5
Neptune from Voyager 2
Discovery of Neptune
• Orbit predicted by
• Englishman John Adams 1845 and
• Frenchman Urbain Leverrier 1846
• First seen by German Johann Galle
1846
Figure 7.6
Jovian Planets - Relative size
Table 7.1
Planetary Properties
Rotation rates
• Not solid - differential rotation
• Atmosphere at various latitudes rotate
different rates
• Magnetosphere rotates
Jovian Planet Physical Properties
• Strong gravity held original atmosphere
- mainly H and He
• Each has dense compact core
• Atmospheres liquid in interior
Analogy 7.1
Saturn would float
Axial tilt
• (Earth 23.5°)
• Jupiter 3°
• Saturn 27°
• Uranus 98° (axis roughly parallel to
ecliptic)
• Neptune 30°
Figure 7.7
Seasons on Uranus
Jupiter’s atmosphere
• Molecular Hydrogen 86%
• Helium 14%
• Small amounts of methane, ammonia,
H 2O
Figure 7.8
Jupiter’s Convection
Cloud bands
• Lighter zones - warm material rising,
high pressure
• Darker belts - cool material sinking, low
pressure
Figure 7.9
Jupiter’s Atmosphere
Atmospheric layers
• Haze on top 110 K
• White ammonia clouds 125 - 150 K
• Ammonium hydrosulfide ice 200 K
• H2O ice
• Gaseous H, He, methane, ammonia,
H 2O
Weather on Jupiter
• Great Red Spot
• White spots
• Brown oval
Figure 7.11
Jupiter’s Red Spot and a white spot
Great Red Spot
• 2X size of earth
• Large hurricane like storm
• More than 300 years old
• Earth hurricanes die out over land
Figure 7.12
Jupiter’s Brown Oval
Figure 7.13
Saturn
a) Voyager 2, b) Cassini
Saturn’s atmosphere
• Molecular H 92.4%
• Helium 7.4% - less than Jupiter liquefied and sank
• Traces of methane and ammonia
• Less gravity, so thicker than Jupiter’s
atmosphere
• Not as colorful (fewer holes/gaps)
Figure 7.14
Saturn’s Atmosphere
Figure 7.15
Saturn Storm from HST a) 2 hour intervals b) infrared
Figure 7.16
Saturn’s “Dragon Storm”
Uranus and Neptune atmospheres
• Molecular H 84%
• Helium 14%
• Methane - Neptune 3%, Uranus 2%
• Methane absorbs long wavelengths
(red)
• Neptune more blue than Uranus
Figure 7.17
Uranus’s Rotation
a), b), c) 4 hour interval
d) rings and clouds, infrared
Figure 7.18
a) Neptune’s Dark Spot (Voyager 2) b) later disappeared
Jupiter’s interior
• Top layers are gas - molecular H
• At several thousand km, liquid
• Liquid metallic H
• Rocky core
Figure 7.19
Jupiter’s Interior
Saturn’s interior
• Top layers are gas - molecular H
• Thinner metallic H layer
• Larger rocky core
Figure 17.20
Jovian Interiors
Jovian magnetospheres
• Stronger than Earth’s
• Caused by fast rotation
• Jupiter - largest and strongest
magnetosphere
• Aurora on Jupiter
Figure 7.21
Pioneer 10 Mission
Figure 7.22
Aurorae on Jupiter
Figure 7.23
Jovian Magnetic Fields
Jovian internal heating
• Jupiter - emits 2X more energy than
absorbed (left over heat)
• Saturn - 3X (helium rain and
gravitational compression)
• Neptune - 2.7X
Discovery 7-1
A Cometary Impact