The Jovian PlanetsThe Jovian Planets

The Gas Monsters.The Gas Monsters.

JupiterJupiter

Size of JupiterSize of Jupiter

• Jupiter is the fifth planet from the Jupiter is the fifth planet from the Sun and by far the largest. Jupiter is Sun and by far the largest. Jupiter is more than twice as massive as all more than twice as massive as all the other planets combined (318 the other planets combined (318 times Earth).times Earth).

Orbit: 778,330,000 km (5.20 AU) from Sun

Diameter: 142,984 km (equatorial)

Mass: 1.900e27 kg

MythologyMythology

• Jupiter (a.k.a. Jove; Jupiter (a.k.a. Jove; Greek Zeus) was Greek Zeus) was the King of the the King of the Gods, the ruler of Gods, the ruler of Olympus and the Olympus and the patron of the patron of the Roman state.Roman state.Zeus was the son Zeus was the son of Cronus (Saturn). of Cronus (Saturn).

CompositionComposition

• The gas planets The gas planets do not have solid do not have solid surfaces, their surfaces, their gaseous gaseous material simply material simply gets denser with gets denser with depth. depth.

CompositionComposition

• Jupiter is about Jupiter is about 90% hydrogen and 90% hydrogen and 10% helium with 10% helium with traces of methane, traces of methane, water, ammonia water, ammonia and "rock". and "rock".

• Jupiter and the other gas planets have high Jupiter and the other gas planets have high velocity winds which are confined in wide bands velocity winds which are confined in wide bands of latitude.of latitude.

• The winds blow in opposite directions in adjacent The winds blow in opposite directions in adjacent bands. bands.

• Slight chemical and temperature differences Slight chemical and temperature differences between these bands are responsible for the between these bands are responsible for the colored bands that dominate the planet's colored bands that dominate the planet's appearance. appearance.

• The light colored bands are called zones; the The light colored bands are called zones; the dark ones belts.dark ones belts.

Atmospheric Belts and Atmospheric Belts and ZonesZones

AtmosphereAtmosphere

• The interior heat of The interior heat of Jupiter probably Jupiter probably causes convection causes convection deep within Jupiter's deep within Jupiter's liquid layers and is liquid layers and is probably responsible probably responsible for the complex for the complex motions we see in motions we see in the cloud tops.the cloud tops.

Voyager Space CraftVoyager Space Craft

• The voyager space The voyager space crafts have given crafts have given us much of the us much of the information we information we know about Jupiter know about Jupiter and Saturnand Saturn

Clouds and SpotsClouds and Spots

The Great Red SpotThe Great Red Spot

GRSGRS

• The Great Red Spot (GRS) has been The Great Red Spot (GRS) has been observed from Earth for more than observed from Earth for more than 300 years300 years

The GRS is an oval about 12,000 by 25,000 km, big enough to hold two Earths. Other smaller but similar spots have been known for decades.

Interior of JupiterInterior of Jupiter

Metallic Hydrogen?Metallic Hydrogen?

IMPACT!IMPACT!

• In July 1994, Comet In July 1994, Comet Shoemaker-Levy 9 Shoemaker-Levy 9 collided with collided with Jupiter with Jupiter with spectacular resultsspectacular results

Jupiter has rings like Saturn's, but Jupiter has rings like Saturn's, but much fainter and smaller (right). They much fainter and smaller (right). They

were totally unexpected and were were totally unexpected and were only discovered when two of the only discovered when two of the Voyager 1 scientists insisted that Voyager 1 scientists insisted that

after traveling 1 billion km it was at after traveling 1 billion km it was at least worth a quick look to see if any least worth a quick look to see if any

rings might be presentrings might be present

MoonsMoons

• Galileo's discovery, in 1610, of Galileo's discovery, in 1610, of Jupiter's four large moons Io, Europa, Jupiter's four large moons Io, Europa, Ganymede and Callisto, are now Ganymede and Callisto, are now known as the Galilean moons).known as the Galilean moons).

• Jupiter has 16 known satellites, the Jupiter has 16 known satellites, the four large Galilean moons and 12 four large Galilean moons and 12 small onessmall ones

SaturnSaturn

MythologyMythology

• In Roman mythology, Saturn is the In Roman mythology, Saturn is the god of agriculture. god of agriculture.

• The associated Greek god, Coronus, The associated Greek god, Coronus, was the son of Uranus and Gaiawas the son of Uranus and Gaiaand the father of Zeus (Jupiter). and the father of Zeus (Jupiter).

• Saturn is the root of the English word Saturn is the root of the English word "Saturday""Saturday"

Mass, Size, and DistanceMass, Size, and Distance

• M =6.58 x 10M =6.58 x 102626 kg kg

• Diameter = 119,000 km equatorial Diameter = 119,000 km equatorial and 107,000 polar.and 107,000 polar.

• Distance to sun = 9.52 AU or Distance to sun = 9.52 AU or 1,426,000,000 km1,426,000,000 km

OrbitOrbit

• Saturn’s orbit is almost spherical. Saturn’s orbit is almost spherical.

• The planet is inclined about 27 The planet is inclined about 27 degrees from vertical.degrees from vertical.

CompositionComposition

• Like Jupiter, Saturn is about 75% Like Jupiter, Saturn is about 75% hydrogen and 25% helium with hydrogen and 25% helium with traces of water, traces of water, methane, methane, ammonia ammonia and "rockand "rock

Saturn’s InteriorSaturn’s Interior

Saturn’s RingsSaturn’s Rings

Ring CompositionRing Composition

• The rings are actually composed of The rings are actually composed of innumerable small particles each in innumerable small particles each in ananindependent orbit.independent orbit.

• They range in size from a centimeter They range in size from a centimeter or so to several meters.or so to several meters.

• A few kilometer-sized objects are A few kilometer-sized objects are also likely.also likely.

Close-up of ringsClose-up of rings

Moons—15!Moons—15!

TitanTitan

• Second largest moon in the Solar Second largest moon in the Solar SystemSystem

• TITAN IS THE ONLY MOON TO HAVE TITAN IS THE ONLY MOON TO HAVE A KNOWN ATMOSPHEREA KNOWN ATMOSPHERE

UranusUranus

MythologyMythology

• Uranus is the ancient Uranus is the ancient Greek deity of the Greek deity of the Heavens, the earliest Heavens, the earliest

supreme godsupreme god..

Size, Mass, DistanceSize, Mass, Distance

• orbit: 2,870,990,000 km (19.218 orbit: 2,870,990,000 km (19.218 AU) from SunAU) from Sun

• diameter: 51,118 km (equatorial)diameter: 51,118 km (equatorial)

• mass: 8.683 x 10mass: 8.683 x 102525 kg kg

Uranus from EarthUranus from Earth

Uranus was the first planet discovered in modern times (March 13, 1781).

CompositionComposition

• Uranus is composed primarily of rock and Uranus is composed primarily of rock and various ices, with only about 15% hydrogen various ices, with only about 15% hydrogen and a little helium (in contrast to Jupiter and and a little helium (in contrast to Jupiter and Saturn which are mostly hydrogen).Saturn which are mostly hydrogen).

• Uranus (and Neptune) are in many ways Uranus (and Neptune) are in many ways similar to the cores of Jupiter and Saturn similar to the cores of Jupiter and Saturn minus the massive liquid metallic hydrogen minus the massive liquid metallic hydrogen envelope.envelope.

• It appears that Uranus does not have a rocky It appears that Uranus does not have a rocky core like Jupiter and Saturn but rather that its core like Jupiter and Saturn but rather that its material is more or less uniformly distributed.material is more or less uniformly distributed.

AtmosphereAtmosphere

• Uranus' Uranus' atmosphere is atmosphere is about 83% about 83% hydrogen, 15% hydrogen, 15% helium and 2% helium and 2% methane.methane.

Rotation of UranusRotation of Uranus• Most of the planets spin on Most of the planets spin on

an axis nearly perpendicular an axis nearly perpendicular to the plane of the ecliptic to the plane of the ecliptic but Uranus' axis is almost but Uranus' axis is almost parallel to the ecliptic. parallel to the ecliptic.

• At the time of Voyager 2's At the time of Voyager 2's passage, Uranus' south pole passage, Uranus' south pole was pointedwas pointed almost directly at the almost directly at the Sun. Sun.

• This results in the This results in the odd fact that Uranus‘odd fact that Uranus‘ polar regions receive polar regions receive more energy inputmore energy input from the Sun than do from the Sun than do its equatorial regions.its equatorial regions.

RingsRings

• Like the other gas planets, Uranus has Like the other gas planets, Uranus has rings.rings.

• Like Jupiter's, they are very dark but like Like Jupiter's, they are very dark but like Saturn's they are composed of fairly large Saturn's they are composed of fairly large particles ranging up to 10 meters in particles ranging up to 10 meters in diameter in addition to fine dust. diameter in addition to fine dust.

• There are 11 known rings, all very faint; There are 11 known rings, all very faint; the brightest is known as the Epsilon ring.the brightest is known as the Epsilon ring.

MoonsMoons

• Uranus has 20 named moons plus 1 recently discovered one which as yet has not been given an official name.

• Unlike the other bodies in the solar system which have names from classical mythology, Uranus' moons take their names from the writings of Shakespeare and Pope.

NeptuneNeptune

MythologyMythology• In Roman mythology Neptune In Roman mythology Neptune

(Greek: Poseidon) was the god of (Greek: Poseidon) was the god of the Sea.the Sea.

Discovery of NeptuneDiscovery of Neptune

• After the discovery of Uranus, it was noticed After the discovery of Uranus, it was noticed that its orbit was not as it should be in that its orbit was not as it should be in accordance with Newton's laws. It was accordance with Newton's laws. It was therefore predicted that another more distant therefore predicted that another more distant planet must be perturbing Uranus' orbit.planet must be perturbing Uranus' orbit.Neptune was first observed by Galle and Neptune was first observed by Galle and d'Arrest on 1846 Sept 23 very near to the d'Arrest on 1846 Sept 23 very near to the locations independently predicted by Adams locations independently predicted by Adams and Le Verrier from calculations based on the and Le Verrier from calculations based on the observed positions of Jupiter, Saturn and observed positions of Jupiter, Saturn and Uranus.Uranus.

Orbit, Mass, DiameterOrbit, Mass, Diameter

• orbit: orbit: 4,504,000,000 km4,504,000,000 km

(30.06 (30.06 AU) from SunAU) from Sundiameter: 49,532 diameter: 49,532 km (equatorial)km (equatorial)mass: mass: 1.0247e26 kg1.0247e26 kg

CompositionComposition

• Neptune's composition is probably similar to Uranus': Neptune's composition is probably similar to Uranus': various "ices" and rock with about 15% hydrogen and various "ices" and rock with about 15% hydrogen and a little helium. a little helium.

• Like Uranus, but unlike Jupiter and Saturn, it may not Like Uranus, but unlike Jupiter and Saturn, it may not have a distinct internal layering but rather to be more have a distinct internal layering but rather to be more or less uniform in composition. But there is most or less uniform in composition. But there is most likely a small core (about the mass of the Earth) of likely a small core (about the mass of the Earth) of rocky material. rocky material.

• Its atmosphere is mostly hydrogen and helium with a Its atmosphere is mostly hydrogen and helium with a small amount of methane.small amount of methane.

AtmosphereAtmosphere

• Like a typical gas Like a typical gas planet, Neptune has planet, Neptune has rapid winds confined rapid winds confined to bands of latitude to bands of latitude and large stormsand large stormsor vortices.or vortices.Neptune's winds areNeptune's winds arethe fastest in thethe fastest in thesolar system, solar system, reachingreaching2000 km/hour.2000 km/hour.

RingsRings

• Neptune also has Neptune also has rings. Earth-based rings. Earth-based observations observations showed only faint showed only faint arcs instead of arcs instead of complete rings, butcomplete rings, butVoyager 2's imagesVoyager 2's imagesshowed them to beshowed them to becomplete rings with complete rings with bright clumps.bright clumps.

Because Pluto's orbit is so Because Pluto's orbit is so eccentric, it sometimes crosses eccentric, it sometimes crosses the orbit of Neptune making the orbit of Neptune making Neptune the mostNeptune the mostdistant planet from the Sun for a distant planet from the Sun for a few years. few years.

MoonsMoons

• Neptune has 8 known moons; 7 small Neptune has 8 known moons; 7 small ones and Triton.ones and Triton.

PlutoPluto

MythologyMythology

• In Roman mythology, Pluto (Greek: Hades) is the god of the underworld. The planet received this name (after many other suggestions) perhaps because it's so far from the Sun that it is in perpetual darkness and perhaps because "PL" are the initials of Percival Lowell.

• Lowell predicted the existence of Pluto

Pluto was discovered in 1930 by a Pluto was discovered in 1930 by a fortunate accident. Calculations which fortunate accident. Calculations which later turned out to be in error had later turned out to be in error had predicted a planet beyond Neptune, predicted a planet beyond Neptune, based on the motions of Uranus and based on the motions of Uranus and Neptune. Not knowing of the Neptune. Not knowing of the error, Clyde W. error, Clyde W. Tombaugh at LowellTombaugh at LowellObservatory inObservatory inArizona did a veryArizona did a verycareful sky survey careful sky survey which turnedwhich turnedup Pluto anyway.up Pluto anyway.

Mass, Size, DistanceMass, Size, Distance

•orbit: 5,913,520,000 km (39.5 AU) from the Sun (average)

•diameter: 2274 km

•mass: 1.27 x 1022 kg

OrbitOrbit

Pluto's orbit is highly eccentric. At times it is closer to the Sun than Neptune (as it was from January 1979 thru February 11 1999). Pluto rotates in the opposite direction from most of the other planets.

PLUTO FROM EARTH PLUTO FROM EARTH BASED TELESCOPEBASED TELESCOPE

CompositionComposition

Pluto's composition is unknown, but its density (about 2 gm/cm3) indicates that it is probably a mixture of 70% rock and 30% water ice much like Triton.

The bright areas of the surface seem to be covered with ices of nitrogen with smaller amounts of (solid) methane, ethane and carbon monoxide.

MoonsMoons

Fortunately, Pluto has a satellite, Charon.

By good fortune, Charon was discovered (in 1978) just before its orbital plane moved edge-on toward the inner solar system.

It was therefore possible to observe many transits of Pluto over Charon and vice versa. By carefully calculating which portions of which body would be covered at what times, and watching brightness curves, astronomers were able to construct a rough map of light and dark areas on both bodies.

Pluto and Charon from HSTPluto and Charon from HST