The document summarizes key facts about the outer planets. It describes Jupiter, Saturn, Uranus, and Neptune as gas giants composed primarily of hydrogen and helium. It discusses their atmospheric compositions and conditions. It also describes their moons, rings, and exploration by Voyager spacecraft. Pluto is described as a small icy body beyond Neptune that is no longer classified as a planet.

1. Chapter 24 Section 3: Outer Planets

2. 23.4 The Outer Planets Outer Planets: Description Outer Planets: Jupiter, Saturn, Uranus, Neptune Pluto is no longer considered a planet. 4 planets are gaseous giants ( Jovian Planets ) Pluto and Xenon are frozen spheres Voyager 1 & 2 probed the 4 gaseous giants Jupiter, Saturn, Uranus, Neptune Pgs. 654 - 659

3. Jupiter: Jupiter Largest Planet in our Solar System Fifth planet in order Revolution = 11.9 years to orbit Rotation = 10 hrs. (fastest of all planets) Voyager 1 & 2 (1979) probed Jupiter Gathered information about Jupiter’s Moons’ Atmospheres Discovered 3 more moons Discovered a faint dust ring orbiting Jupiter

4. Jupiter’s Composition: Hydrogen, Helium, Ammonia, Methane, & water vapor Gaseous Atmosphere, Liquid Mantle, & Solid Core Clouds form color bands; Winds up to 400 km/hr. Great Red Spot : Continuous Atmospheric Storm Lightning has been observed in the atmosphere Radiates 2x as much heat as it receives Believed to be a star “that just didn’t make it”

5. Images of Jupiter

6. Jupiter’s Moons Jupiter’s Moons Jupiter has at least 16 moons Four Largest = Galilean Moons (Discovered in 1610) Io, Europa, Ganymede, Callisto Io: Closest of the Large moons to Jupiter Most volcanic objects in out Solar System Sulfuric Lava produces Reddish/Orange color Holds a thin sulfur dioxide atmosphere Europa: Composed of solid rock covered with ice Tectonic activity Thin oxygen atmosphere

7. Ganymede: Largest moon in the Solar System Larger than Mercury, Surface covered in Ice Slushy Mantle, Solid rock core Callisto: Composed of heavily cratered Rock/Ice Crust Water/Ice mantle with a rocky core

8. Galilean Moons Io with eruption Europa Ganymede Callisto

9. Saturn Sixth planet; 30 year orbit; 11 hr rotation 1980 & 1981 surveyed by the Voyagers “ Ringed Planet” Second Largest planet Very low density (would float in water) Atmospheric composition: Mostly hydrogen & helium; also ammonia, methane Liquid Hydrogen/helium mantle Small rocky core

10. Saturn: Rings composed of 100’s of ringlets Ringlets are made up of ice & rock particles At least 18 moon orbit Saturn (Most of any planet) Largest moon = Titan (2 nd largest in Solar System) Real atmosphere of nitrogen, argon, & methane Thick, smog clouds cover Titan Surface temp. = -180 0 C (-292 o F)

12. Uranus Smallest of the gas planets Discovered in 1781 7 th planet, 84 year orbit, 17 hour rotation ** Average Temp. = -328 o F

13. Uranus: Voyager 2 surveyed (1986) Discovered 10 unknown moons (making 15 total) 5 largest almost identical Dark color, lack atmosphere, crater riddled Discovered several dark rings Detected a magnetic field tilted 60 0 from axis Atmosphere: Hydrogen, Helium & Methane Methane gives planet a blue/green tint Liquid mantle of water, methane, & ammonia Rocky core ** Rotational axis lays on its side (Spins like a tire)

14. Neptune Last of the gas planets; discovered in 1846 Orbit overlaps Pluto’s at 2 points Change position 8  9 & 9  8 1 orbit = 165 years; 1 rotation = 16 hrs Atmosphere: Hydrogen, Helium, Methane Methane gives Neptune bluish tint Winds = 2200 km/hr; Temperature = -417 0 F Has a dark spot = storm in it’s atmosphere Liquid mantle: water, methane, & ammonia Core: solid rock

15. F. Neptune (continued) Voyager 2 detected 6 moons (Totaling 8) Largest moon = Triton Has a thin nitrogen atmosphere Constantly erupting methane geysers Neptune also has rings (thin & thicken at different places)

17. Pluto: G. Pluto Discovered in 1930; smallest planetoid Between 1979 & 1999 Pluto orbited inside Neptune Rest of the time the ninth planet Orbit = 248 years Has a different orbital plane (tilted 17 0 from other planets)

18. Pluto: Pluto (continued) Surrounded by a minimal atmosphere Temperature = -364 o F Solid rocky crust One Moon, Charon (½ diameter of Pluto) Orbits very close to Pluto Sometimes considered “a double planet” with Pluto

19. H. Xenon Discovered January 8 th , 2005 20 % larger than Pluto Orbital time unknown; Rotational time unknown Has one known moon Dark & cold (below -225 0 C or -373 o F) Has not been “officially” named yet

20. Kuiper Belt Kuiper Belt Discovered by the Hubble Telescope Vast disk of icy comets Located near Neptune’s orbit

21. Voyagers’ Continuing Mission After passing Saturn in 1980 Voyager 1 headed out of our Solar System After passing Pluto in 2000 Voyager 2 headed out of our Solar System Both are still transmitting information back to Earth about deep space, and our sun’s long range influence of charged particles