• 3rd brightest object in night sky

• Alternating light & dark bands

• Giant Red Spot

• Galilean moons (Io, Callisto, Ganymede, Europa)

•Much fainter than Jupiter; twice the distance from Earth

•Atmospheric bands less distinct

•Moons•Ring system

Voyager 1 and Voyager 2Voyager 1 and Voyager 2•Launched in 1977Launched in 1977•Arrived at Jupiter in 1979Arrived at Jupiter in 1979•Both visited SaturnBoth visited Saturn•Voyager 2 flew by Uranus and Voyager 2 flew by Uranus and

NeptuneNeptune

GalileoGalileo• Launched in 1989Launched in 1989• Arrived at Jupiter in 1995Arrived at Jupiter in 1995• Orbited Jupiter and its Orbited Jupiter and its

moonsmoons• Was crashed into Jupiter in Was crashed into Jupiter in

20032003

Cassini- HuygensCassini- Huygens• Launched in 1997Launched in 1997• Arrived at Saturn in 2004Arrived at Saturn in 2004• Launched the Huygens probe Launched the Huygens probe

which landed on Titanwhich landed on Titan• Continues to orbit Saturn Continues to orbit Saturn

and its moonsand its moons

• Uranus was discovered in 1781 by William Herschel

• Originally named after King George III

• After some study, the predicted and observed position of Uranus were off. This led to the search and discovery of…

Neptune•Discovered in 1846 by Johann Galle

•Neptune is not visible to the naked eye

• Due to the composition of the planets (gas) the equator rotates at a different rate than near the poles

• Jupiter’s equator rotates at 9h50m, higher latitudes are 6 minutes slower

• Produces an oblate shape

Extra-solar PlanetsExtra-solar Planets

•318x more massive than Earth

•Diameter is 11x Earth’s •3° axial tilt•Distance from Sun: ~5 A.U.•Gravity = 2.53x Earth’s•Orbital Period: ~12 earth years

Composition:

•Molecular hydrogen (H2)

•Helium

•Trace amounts of CH4, NH3 and H2O

The Great Red Spot•A large hurricane-like storm that has been around for over 300 years

•Two earths could fit inside

Belts and Zones•Belts are the dark colored bands

•Zones are the light colored bands

•Caused by convection currents

Where does the energy come from?

•Sun’s radiation (small)•Lightning discharges (small)•Internal heat source**Jupiter gives off more than it gets from the Sun

In 1994 Comet Shoemaker-Levy (22 pieces of it) smashed into Jupiter leaving the dark spots seen in this photo

•95x more massive than Earth

•9.5x Earth’s radius•27 axial tilt•Distance from Sun: 9.5 A.U.•Orbital Period: 29 years•Gravity: 1.1x Earth’s

Gases:

•Molecular Hydrogen (H2): 92%

•Helium: 7.4%•Some of the helium liquefied

and sank to interior

•Trace amounts of CH4 and NH3

• Rings are wide but thinRings are wide but thin

• About 106,000 km wideAbout 106,000 km wide

• Thickness of rings: a few hundred metersThickness of rings: a few hundred meters

• Composition mainly water, ice, and carbon Composition mainly water, ice, and carbon compounds and is not uniform across ringscompounds and is not uniform across rings

• Sizes range from centimeters to metersSizes range from centimeters to meters

• Rings structured into ringlets and gapsRings structured into ringlets and gaps

The Roche Limit:The Roche Limit:• Any object will break apart by tidal forces if it gets Any object will break apart by tidal forces if it gets

too close to the planettoo close to the planet• Distance of breakup is called the Distance of breakup is called the Roche limitRoche limit

and is 2.44 planetary radiiand is 2.44 planetary radii• For rings to persist they must be replenishedFor rings to persist they must be replenished• Existence of side-by-side ringlets of different Existence of side-by-side ringlets of different

compositions indicates rings supplied by varied compositions indicates rings supplied by varied comets and asteroidscomets and asteroids

http://saturn.jpl.nasa.gov/

http://saturn.jpl.nasa.gov/

• Channels cut by running liquid• Evidence of thunderstorms• Atmospheric pressure 50% >

than earth’s

• Ethane (C2H6) lakes confirmed

• Hydrocarbon dunes

http://saturn.jpl.nasa.gov/

http://saturn.jpl.nasa.gov/

Reflection of Sunlight off Titan Lake

http://saturn.jpl.nasa.gov/

http://saturn.jpl.nasa.gov/

http://saturn.jpl.nasa.gov/

•Discovered in 1781 by William Herschel

•Composed of 83% hydrogen, 15% helium, 2% methane

•Winds up to 360 mph•Mean cloud temperature = -

193°C

•Distance from Sun: 19 A.U.•Period = 84 years•Blue color due to methane in

atmosphere•Mass = 14.5x Earth’s mass•At least 22 moons

•Diameter = 4x earth’s•Ring system•Axial tilt = 98°; Uranus is on

its side!•Magnetic Poles tilted > 60°

with respect to its axis

•Discovered in 1846 by Johann Galle

•A day on Neptune is 16 hours and 6.7 minutes

•Diameter = 4x earth’s•winds blow up to 2,000 kph

(1,200 mph) an hour

•Distance from Sun: 30 A.U.•Period = 164 years•Blue color (methane)•Mass = 17x Earth’s mass•Ring arcs•Neptune has cloud beltsNeptune has cloud belts

• One of its six moons is TritonOne of its six moons is Triton

• Triton’s orbit is retrograde Triton’s orbit is retrograde

• Triton has an atmosphereTriton has an atmosphere

• At least one geyser caught in At least one geyser caught in eruption by the passing eruption by the passing Voyager IIVoyager II