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Astronomy Chapter 8

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Which of the following is NOT a general characteristic of the four jovian planets in our solar system?
They are higher in average density than are the terrestrial planets.
Which of the following best describes the internal layering of Jupiter, from the center outward?
core of rock, metal, and hydrogen compounds
thick layer of metallic hydrogen
thick layer of liquid hydrogen
layer of gaseous hydrogen
cloud layer
Which of the following statements comparing the Jovian interiors is NOT thought to be true?
they all have the same exact set of internal layers, though these layers differ in size
Overall, Jupiter's composition is most like that of _________.
the sun
Jupiter's colors come in part from its three layers of clouds. Which of the following is NOT the primary constituent of one of Jupiter's cloud layers?
clouds of sulfuric acid
How do typical wind speeds in Jupiter's atmosphere compare to typical wind speeds on Earth?
They are much faster than hurricane winds on Earth.
What is the Great Red Spot?
a long lived, high pressure storm on Jupiter
What atmposheric constituent is responsible for the blue color of Uranus and Neptune?
Methane
How does the strength of Jupiter's magnetic field compare to that of Earth's magnetic field?
Jupiter's magnetic field is about 20,000 times as strong as Earth's.
Which of the following statements about the moons of the Jovian planets is NOT true?
most of the moons are large enough to be spherical in shape, but a few have the more potato like shapes of asteroids
Which statement about Io is true?
Io is the most volcanically active body in our solar system.
Which moon has a thick atmosphere made mostly of nitrogen?
Titan
The Hugyens probe took numerous pictures as it descended to Titan's surface in 2005. What did the pictures show?
features of erosion, including what appeared to be dry river valleys and lakebeds
Which large Jovian moon is thought to have been captured into its present orbit?
Triton
Which moon is considered likely to have a deep, subsurface ocean of liquid water?
Europa
Suppose you could float in space just a few meters above Saturn's rings. What would you see as you looked down on the rings?
countless icy particles, ranging in size from dust grains to large boulders.
Which statement about planetary rings is NOT true?
Saturn's rings formed along with its moons 4.6 billion years ago.
Which of the following gases is NOT a significant ingredient of the jovian planet atmospheres?
carbon dioxide
Jupiter and the other jovian planets are sometimes called "gas giants." In what sense in this term misleading?
They actually contain relatively little material in a gaseous state.
What would happen to Jupiter if we could somehow double its mass?
Its density would increase but its diameter would barely change
According to our theory of solar system formation, why did Uranus and Neptune end up to be much less massive than Jupiter and Saturn?
Particles in the solar nebula were more spread out at greater distances, so that accretion took longer and there was less time to pull in gas before the solar wind cleared the nebula.
Why does Jupiter have three distinct layers of clouds?
The three layers represent clouds made of gases that condense at different temperatures.
Which of the following best explains why we see horizontal stripes in photographs of Jupiter and Saturn?
The light stripes are regions of high clouds, and the dark stripes are regions where we can see down to deeper, darker clouds
Uranus and Neptune have methane clouds but Jupiter and Saturn do not. Which factor explains why?
Temperatures on Jupiter and Saturn are much too high for methane to condense
Which Jovian planet has the most extreme seasonal changes?
Uranus
Why is the radiation so intense in the region that traces Io's orbit around Jupiter?
The region is full of gases that become ionized after they are released from volcanoes on Io.
Which of the following best explains why many Jovian moons have been more geologically active than the moon or mercury?
Jovian moons are made mostly of ice that can melt or deform at lower temperatures that can the rock and metal that make up the Moon or Mercury.
All of the following statements are true. Which one is most important in explaining the tremendous tidal heating that occurs on Io?
Io orbits Jupiter on an elliptical orbit, due to orbital resonances with other satellites.
Which of the following is NOT a piece of evidence supporting the idea that Europa may have a subsurface ocean?
Astronomers have detected small lakes of liquid water on Europa's surface.
Which of the following is most unlikely to be found on Titan?
lakes of liquid water in the warmer equatorial regions
Why do astronomers believe that Triton is a captured moon?
Triton orbits Neptune in a direction opposite that of Neptune's rotation
Which statement about Saturn's rings is NOT true?
The rings must look much the same today as they did shortly after Saturn formed.
According to current understanding, which of the following is required in order for a planet to have rings?
The planet must have many small moons that orbit relatively close to the planet in its equatorial plane.
Jupiter and Saturn are made mostly of what?
Hydrogen and Helium gas
Uranus and Neptune are made mostly of what?
Hydrogen compounds
Jovian planet formation:
beyond the frost line: could accumulate ice

Hydrogen compounds are more abundant
Jovian planet differences
amount of Hydrogen and Helium gas accumulated

1. Timing: planet that forms earliest captures the most gas
2. Location: planet that forms in a denser part of the nebula forms its core first
Why are Uranus and Neptune denser than Saturn
because they have less Hydrogen and Helium gas proportionately
Adding mass to a jovian planet compresses the underlying gas layers
Jupiter has so many gases and so it's denser

Greater compression is why Jupiter is not much larger even though it is more massive
Interiors of Jovian planets
no solid surface
layers under high pressures and temperatures
cores made of hydrogen compounds, metals, and rock
layers are different for the different planets
Inside Jupiter
Core: rock, metals, and hydrogen compounds
Metallic Hydrogen
Liquid Hydrogen
Gas Hydrogen

High pressure of Jupiter causes the phase of hydrogen to change with depth

Hydrogen acts like a metal at great depths because electrons can move freely
Comparing Jovian interiors
cores have similar composition
low pressure- Uranus and Neptune cause them not to have metallic hydrogen
Saturn vs Jupiter interiors
same layers as Jupiter.. Metallic hydrogen layers are smaller
Jupiter's magnetosphere
strong magnetic field gives it an enormous magnetosphere
Jupiter's atmosphere
Hydrogen compounds form clouds
Different cloud layers correspond to freezing points of different hydrogen compounds

other jovian planets have similar cloud layers

Ammonium sulfide: red/brown
Ammonia: white
Saturn's colors:
Saturn's layers are similar but are deeper in and farther away from the Sun, more subdued
Methane on Uranus and Neptune
Methane gas absorbs red light and transmits blue light... blue light reflects off methane clouds making planets look blue
Weather of Jovian Planets
all have strong winds and strong storms
Medium and Large moons:
enough self gravity to be spherical
lots of ice
formed in orbit around jovian planets
circular orbits in same direction as planet's rotation
Small moons
far more numerous
not enough gravity to be spherical "potato shaped"
Io:
most volcanically active body in the solar system.

Eruptions continue to change Io's surface.

Squished and stretched as it orbits
Why is Io's orbit so elliptical?
because of orbit of other moons

orbital resonance: every 7 days, three moons line up

tugs add up making all 3 orbits elliptical
Europa:
tidal stresses crack Europa's surface ice

tidal flexing closes crack, grinds up ice
tidal flexing opens crack, leaving two ridges

Covered with ice not volcanoes

Interior also warmed by tidal heating.. it's entire surface is an ocean, ice layer on top
Ganymede:
largest moon in the solar system.
evidence of geological activity
tidal heating and heat from radioactive decay?
Callisto
classic cratered iceball
no tidal heating
no orbital resonances
magnetic field?
Titan
Saturn's only large moon
only moon in the solar system with a thick atmosphere
mostly nitrogen

Surface: liquid methane, rocks made of ice
Medium moons of Saturn
almost all of them show evidence of past volcanism and or tectonics

Enceladus: very large geiser, stripes due to geiser
craters on only one side
Medium moons of Uranus
Miranda: varying amounts of geological activity, large tectonic features, few craters
Neptune's moon Triton
similar to Pluto but larger
Evidence of past geological activity
Why are Jovian moons more geologically active than terrestrial planets?
Rocky planets: rock melts at higher temperatures, only large rocky planets have enough heat for activity

Icy moons: Ice melts at a low temperature, tidal heating can melt internal ice
What are Saturn's rings like
made up of tiny individual particles
orbit Saturn's equator
very thin
Why do Jovian planets have rings?
all four of them have rings. They formed from dust created in impacts on moons orbiting these planets. Rings aren't leftover form planet formation. The particles are too small to have survived that long. There must be a continuous replacement of tiny particles.