Outer Planets (Jovian Planets)

-planets beyond the asteroid belt

- also known as the gas giants

- all 4 have a ring system made of dust and icy debris

Jupiter - -5th from the sun, Largest

planet

Its mass is more than 300 Earth’s

Revolution = 11.86 years (˜12 years)

Fastest rotation = 9 hrs. 50 min.

Atmosphere – very thick mostly hydrogen(92%), helium, ammonia, methane, and traces of water vapor.

(if Jupiter was a little bigger it may have became a star)

Temperature of outer surface is - 160°C

Because of different chemical make up

and motions of Jupiter – various color

bands and storms are observed (lighting

also) Example: Great Red Spot – High

pressure storm = 3 Earths’ in size

(observed for 400 years)

Has several thin rings (sulfur and dust)

69 plus moons (4 largest called Galilean moons)

Io – active volcano’s

Europa – thick icy crust (may have liquid water)

Ganymede – also icy crust largest moon

Callisto – heavily cratered

Gravity 2.5 times more than Earth

Saturn – 6th planet from the sun

-ringed planet (2nd largest)

Revolution = 29.5 years

Rotation = 10 hrs. 39 min.

Very cold -176°C

Atmosphere – hydrogen, helium, ammonia, etc.

(many color bands in atmosphere)

Lowest average density (could float on water)

Rings – very complex – made of several broad rings, each composed of hundreds of ringlets. Made of countless dust, rock, and ice particles.

61 + moons – Largest is Titan (1/2 size of Earth) its atmosphere of nitrogen, argon & methane

Space probe : Cassini, July, 2004 took best pictures of Saturn and landed a smaller probe on Titan.

Other Space probes sent to Jupiter/Saturn:

Pioneer I & II 1973-75

Voyager I & II 1979-82 (Voyager I farthest spacecraft)

Galileo 1995 – Jupiter & its moons

Uranus – 7th from the sun

god of harvest discovered by William Herschel (1781)

Revolution = 84 years

Rotation = 17 hrs (retrograde)

has the most tilted axis 87° (tilted on

its side)

atmosphere – hydrogen, helium, some methane (gives it a blue-green color)

temperature average = -214°C

12 thin rings largest is Triton

27 moons

Neptune – 8th planet from the sun

-god of the sea, discovered in 1846 mathematically

Revolution = 165 years

Rotation = 16 hrs.

Atmosphere – hydrogen, helium, methane (make it bluish – twin of Uranus)

Temperature = -225°C

Space probes have found great dark spot and white spots showing active storms

6 thin rings, which are thicker in some areas

14 moons largest called Triton

Dwarf Planets: 8 + are know

Trans- Neptunian objects -

Kuiper Belt objects

- mostly ice chunks debris

Pluto – 9th object from the sun

- god of the underworld/dead

- discovered in 1930

- revolution = 248.5 years

- temperature = -235°C

- 5 moons largest called Charon

New Horizon space took 9 years to reach Pluto – 1st space probe to gather info on (July 2015)