“I’m so down to earth, I’m bringing gravity back.” Tinie Tempah Reading: Chapter 11: Gas Giants Chapter 12: Rings, moons, dwarf planets. Make-up tests need to be done before class on Wednesday.

The Gas Giant Planets (Jovian and Neptunian). What are their common features in contrast to the Terrestrial planets?

What are their common features in contrast to the Terrestrial planets? The Jovian Planets. What are their common features in contrast to the Terrestrial planets? * All very massive- gas giants. (318, 95, 15, & 15 Earth masses) * No solid, observable surfaces * All have rings * All have many moons. * All are past the asteroid belt. (Where it is colder.)

Jupiter's moons Jupiter has at least 63 moons. The 4 largest are known as the Galilean moons,

56 known moons

Uranus has at least 21 moons, but only 5 are of reasonable size. All have densities of "dirty snowballs" between 1.3 and 1.6 g/cc.

Neptune has 14 known moons.

Europa ~20-180 million years Structure changes as they get further from Jupiter. Surface Age: Io < few million Europa ~20-180 million years Ganymede ~3 billion years Callisto: 4-4.5 billion years old Density = 3.5 g/cc Density = 3.0 g/cc Density = 1.9 g/cc Density = 1.8 g/cc

Jupiter’s other moons are captured asteroids

*Titan is larger than Mercury and more massive than Pluto. *It has an atmosphere composed mostly of N2 like Earth's but 50% thicker than ours. *94k (- 290F) at Titan's surface. *At its distance from the Sun, Titan is at the triple point of ethane/methane

Round → massive Clearly defined features → solid surface Hazy edge/clouds → atmosphere

Mountain range → plate tectonics! Radar image: Crater; one of only 5! Young surface 10s Myrs Mountain range → plate tectonics!

3 observations & meanings Dark streaks are sand dunes → wind & weather River delta below → rain! But too cold for water. No craters in this image! 3 observations & meanings

This dark, smooth area is a lake. This is an island This is an island T= -290oF This is a river channel

This is a volcano: large round feature, small round top, lines from it are ‘lava’ channels. Cryovolcano

The top is a (dry at the time) lake bed The top is a (dry at the time) lake bed. Bottom are hills with river channels. This means there is rain!!!!

True color image from the surface. Look around the ‘rock’ in the middle- see how it has been washed out around it? Like flowing liquid. This is like ‘rocks’ in ‘sand’ but there is no rock, it is all made of water ice.

The blue things are lakes! 300 miles across. The blue things are lakes!

Titan is a round, massive, solid object surrounded by a thick, opaque atmosphere. The surface is incredibly young, indicating many erosive processes including plate tectonics (mountain ranges), rain (river channels), and volcanoes.

Density = 1.88 g/cc A liquid region within the ice.

Titan.... the other Earth. It rains, it pours, it snows, it evaporates. There are volcanoes and plate tectonics, and few (49 estimated) craters. There's wind, sand dunes, river beds, and lots of erosion. And is there life?

Other moons * Average density of Saturn's moons (except Titan) is ~1.3g/cc: basically they may have rocky cores, but contain substantial amounts of ice.

Enceladus

Iapetus

Iapetus: a giant walnut

Epimetheus: A captured asteroid?

Epimetheus: A captured asteroid?

Hyperion.

Hyperion.

Hyperion. Density = 0.6 g/cc

Miranda

Triton: Neptune's moon

Triton is ~25% water-ice with the rest being rocky (Density=2. 0g/cc) Triton is ~25% water-ice with the rest being rocky (Density=2.0g/cc). Triton has a young surface w/ few craters. Triton orbits Neptune retrograde and rotates at a highly inclined angle. This means it was a captured moon and will eventually fall into Neptune or break up.

Look at all the water!

Quiz 6: How many of the Jovian planets have rings? A) 0 B) 1 C) 2 D) 3 E) 4 F) 6