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 reached Saturn reached Uranus 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 2 O

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 K Ammonium hydrosulfide ice 200 K H 2 O ice Gaseous H, He, methane, ammonia, H 2 O

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 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