The outer planets

1. The outer planets What do the outer planets have in common? What are the characteristics of each outer planet?

2. The outer planets are large and massive like Giants and made out of gas. • The outer planets are Jupiter, Saturn, Uranus, Neptune. • How do they differ from Earth? Gas giants do not have solid surfaces. • What are the main gases that make up gas giants? hydrogen and helium.

3. What feature do gas giants have that earth does not? rings of ice and rock. • How do moons of gas giants and earth’s moon differ? Earth has one moon, gas giants have many moons. Some of the moons of gas giants have their own atmospheres, unlike Earth’s moon.

4. Characteristics of each outer planet • Jupiter is the largest planet in the solar system. It takes about 12 years to orbit the sun and almost 10 hours to rotate on its axis. • How massive is Jupiter? About 2 ½ times greater than all the other planets together. • What object in the solar system is more massive than Jupiter? The sun. • What is a notable feature of Jupiter’s atmosphere? The great red Spot, a storm larger than Earth. • How many moons – Jupiter have? At least 63.

5. Jupiter’s structure: a thick mantle of liquid hydrogen and helium surrounds Jupiter’s core. • Much of the planet is liquid. • Why? The force of gravity is huge because Jupiter is so massive. The hydrogen and helium are under great pressure, which causes them to be compressed into the liquid state. • Students page 156 figure 2 the great red Spot. It illustrates the storm in Jupiter.

6. The moons of Jupiter • Jupiter’s four largest moons are larger than Earth’s moon. • The four moons are: Ganymede, Calisto, Lo, Europa. • which of these moons is the largest? Ganymede • If Ganymede is larger than Mercury why is Ganymede not a planet? It is not in its own orbit around the sun. It orbits Jupiter. • How is Lo different from the other moons? Lo has active volcanoes and is not icy.

7. Summary of Jupiter’s moons; • Ganymede is Jupiter’s largest moon • Callisto is second to Ganymede in size. It has less ice. • Lo is not icy. It has many active volcanoes. • Europa is covered with ice. There may be liquid water below the ice. If there is water there might be life.

8. Saturn • Saturn is distinguished by its rings. • What are Saturn’s rings made of? Chunks of rock and ice. • What are Saturn’s rings like? There are many broad, thin rings. • What keeps some of Saturn’s rings in place? Gravity from tiny moons that orbit on either side of the rings.

9. How are Saturn and Jupiter similar? Both have atmospheres made up of hydrogen and helium. Both have clouds and storms. • How are Saturn and Jupiter different? In addition to being smaller than Jupiter, Saturn is also less dense. • How are Saturn’s moons like those of Jupiter? Both planets had many moons. The largest moon of each is bigger than the planet Mercury. • Students page 158,figure 4, answer the questions

10. Uranus • Uranus has a distinctive axis of rotation. • How is its rotation different from that of the other planets ? Uranus rotates from top to bottom instead of from side to side. • What do astronomers think caused it’s unusual rotation? It was probably hit by a large object that knocked it on its side. • Seasons on Uranus are unusual. During spring and fall, all parts of the planet experience equal hours of sunlight and darkness. During winter and summer one hemisphere is always in darkness while the other is always in sunlight.

11. Neptune • Neptune is similar in size and color to Uranus • Neptune is called the blue planet; its atmosphere contains visible clouds. • How many moons does Neptune have? at least 13. • What is the name of Neptune’s largest moon? Triton. • What is unusual about a region near Triton’s South Pole? It is covered by nitrogen ice.

12. Students page 161, apply it. • Assess your understanding. • Homework: • Draw an image of Saturn and Jupiter and then compare and contrast the similarities and the differences between the two planets. • Draw an image and compare and contrast Uranus and Neptune.