• Jupiter – NeptuneJupiter – Neptune

• The Dwarf PlanetsThe Dwarf Planets

• Minor Solar System BodiesMinor Solar System Bodies

JupiterJupiter

• Mass = 318 Earths or greater than 2.5 times the combined mass of all other planets.

• Only 1/800 as massive as the Sun.

• Would have evolved into a small star if it had 80 times more mass.

JupiterJupiter

• Most rapidly rotating planet: 1 Jupiter-day = 10 Earth-hours.

• Jupiter gives off more heat than it receives from the Sun - producing huge convection currents in the atmosphere.

Sulfur Compounds (orange-brown)

Methane Ice(brighter, higher clouds)

Atmosphere is mostly H and He with minor amounts of methane, ammonia and water.

• The Great Red Spot:

– Hurricane-like storm caught between two jet-stream bands of atmosphere.

– 2 to 3 Earths in diameter.

– Has lasted for more than 300 years.

At 600 miles depth, hydrogen At 600 miles depth, hydrogen gas is compressed into liquid gas is compressed into liquid hydrogenhydrogen

Rocky and metallic core: Rocky and metallic core: about 10-15 Earth-massesabout 10-15 Earth-masses

Jupiter’s MoonsJupiter’s Moons

• 67 moons discovered so far

• 4 largest moons are all geologically distinct worlds

The Galilean MoonsThe Galilean Moons

Io

Europa

Ganymede

Callisto

IoIo

• The most volcanically active body in the Solar System.

• Similar in size to Earth’s moon.

• Stress from the tidal flexing of Io’s surface generates internal heat (100 m tides).

The young volcanic surface of Io

Coloration from a variety of sulfur compounds

Eruption plumes up to 300 km high spew from Io’s volcanoes.

Like on Earth, silicate-based lavas are erupted on Io’s surface.

EuropaEuropa

• Covered in a highly fractured crust of water ice.

• Similar in size to Earth’s moon.

• May be an ocean of liquid water beneath the surface.

• Tidal forces cause internal heating which produces ice-tectonics.

• One of the youngest geological surfaces.

EuropaEuropa

Image taken by the Galileo space probe: 30 X 70 km area of Europa’s “chaos terrain”.

GanymedeGanymede

• Larger than Mercury: largest moon in Solar System.

• Outer layer composed mostly of water ice.

• Surface composed of a collage of geological terrains of different ages.

CallistoCallisto

• Slightly smaller than Mercury.

• Composed of a mixture of water ice and rock.

• Heavily cratered and least active of Jupiter’s moons.

SaturnSaturn

• Mass = 95 Earths

• Twice as far from the Sun as Jupiter

• Similar composition and internal structure to Jupiter

• Winds in atmosphere exceed 1500 km/hr (930 miles/hr).

SaturnSaturn

• The least dense of all of the planets: 0.7 times the density of water.

• Gives off more heat than it receives from the Sun.

Cyclonic storms in Saturn’s atmosphere

Saturn’s RingsSaturn’s Rings

• The main rings are more than 100,000 km across, but less than 100 m in thickness.

• Composed of ice and rock fragments with sizes ranging from dust to boulder-sized particles.

Gravitational influence of moons that coexist with rings play a role in determining their structure.

Saturn’s Moons:Saturn’s Moons:62 Known Moons62 Known Moons

Dione

Mimas

Tethys

Titan

Enceladus

Rhea

TitanTitan

• The largest of Saturn’s moons: larger than Mercury.

• Has a thick nitrogen atmosphere with traces of organic compounds such as hydrocarbons.

• Surface temperature: minus178°C

• Titan’s surface is composed mostly of dirty water ice and hydrocarbon ice.

Rounded pebbles of water ice in hydrocarbon soil.

Lakes of liquid methane and ethane detected by radar.

Surface apparently shaped by erosion with drainage channels and shoreline-like features

EnceladusEnceladus

• The brightest body in the Solar System.

• Has an icy surface consisting of both young and old geologic terrains.

• Tectonic deformation of surface = fissures and ridges.

Cryovolcanism: eruptions produced by partial melting of ice rather than silicate rocks.

RheaRhea

IapetusIapetus

DioneDione

HyperionHyperion

MimasMimas

UranusUranus

• Mass = 15 Earths

• Axis of rotation is turned over so that the planet rotates “on its side”.

• Has dark rings of dust and ice.

• Atmosphere is mostly H and He with water, ammonia and methane ice.

• Methane gives planet a blue-green color.

Uranus’ MoonsUranus’ Moons

• 27 known moons.

• Mostly composed of water ice and rock.

• The strangest moon, Miranda consists of a “jigsaw puzzle” of different geologic terrains.

Miranda’s Bizarre Surface – probably tectonic in origin.

Ariel’s Fault-Bound ValleysAriel’s Fault-Bound Valleys

NeptuneNeptune

• Mass = 17 Earths

• Similar composition to Uranus.

• Has a dynamic atmosphere with winds as great as 1,500 mi/hr.

• Has a ring system.

“Great Dark Spot”

“Small Dark Spot”

Neptune’s MoonsNeptune’s Moons

• Has 13 known moons.

• The 6 smaller moons orbit in opposite directions of the 2 largest moons.

TritonTriton

• Largest moon with a retrograde orbit in Solar System.

• Nearly the size of Earth’s moon.

• Coldest surface temperature measured in solar system: minus 235°C

• Has a thin nitrogen atmosphere.

TritonTriton

• Surface composed of frozen methane, nitrogen, and water-ice.

• Surface shaped by cryovolcanism.

• Volcanoes may erupt a mixture of nitrogen gas, water-ice, ammonia, methane, and dust.

PlutoPluto

• Mass = 0.002 Earths.

• Surface temperature: -235°C to -210°C.

• Is composed of a mixture of ice and rock – surface covered with frozen nitrogen.

• 5 moons discovered so far.

Pluto’s very elongate and inclined orbit: occasional passage inside Neptune’s orbit.

• Pluto and Charon orbit about a common center of mass located above Pluto’s surface.

• Charon and Pluto are so similar in size, they are referred to as a double dwarf planet.

In 2006, Pluto was officially classified as a dwarf In 2006, Pluto was officially classified as a dwarf planet by the International Astronomical Union.planet by the International Astronomical Union.

Before the 1850s, the Solar System consisted of more than 8 planets until some of the bodies were classified as asteroids.

The Dwarf PlanetsThe Dwarf Planets

• Dwarf planets – A new class of planets:

– Celestial bodies that orbit the Sun.

– Have sufficient gravity to maintain a rounded shape.

– Are not satellites to more massive bodies.

– Unlike planets, they lack the gravity to have cleared away other bodies around their orbits (orbital dominance).

The Dwarf PlanetsThe Dwarf Planets

Pluto Eris Ceres

Beyond Pluto’s orbit.

Larger than Pluto.

Located in the Kuiper Belt.

Located in the Asteroid Belt.

The Dwarf PlanetsThe Dwarf Planets

• Most recent Kuiper Belt objects to be given dwarf planet status by the IAU.

Haumea Makemake

Beyond PlutoBeyond Pluto

• Hundreds of icy bodies similar to Pluto are located beyond the orbit of Neptune in the Kuiper Belt.

– Disk-shaped region past the orbit of Neptune extending from 30 to 50 AU from the Sun.

– Also contains numerous comets.

CometsComets

• Comet: small solar system bodies that are loose masses of ice, dust, and rocky material.

• Leftover debris from the formation of the Solar System.

Image of Comet 67P/C-G taken by the Rosetta spacecraft (ESA) in August, 2014

Close up views of the surface taken on November, 2014.

Comet Ison in November, 2013

Comet McNaught (January, 2007)

Nucleus of Halley’s Comet imaged by the Giotto space probe in 1986. Every 76 years, the comet returns to the inner Solar System.

Comet Hale-Bopp (April, 1997) will make a return Comet Hale-Bopp (April, 1997) will make a return appearance in the year, 4385.appearance in the year, 4385.

The Asteroid BeltThe Asteroid Belt

• Asteroids: minor bodies of rocky and metallic material (compositions like those of terrestrial planets).

– More than 600,000 discovered so far.

• Meteoroids: smaller fragments.

The Asteroid BeltThe Asteroid Belt

Leftover debris from the nebula that formed the Solar System.

Asteroid Eros imaged by the NEAR-Shoemaker probe.

Image of Vesta taken by the Dawn spacecraft in the summer of 2011.

At 940 km in diameter, the dwarf planet, Ceres is the largest member of the asteroid belt.