Chapter 7: The Outer Planets & Their Moons (Lecture Notes)
the rings are composed of hundreds or thousands of _____.
"ringlets"
what are the origins of saturn's rings?
An icy moon collided and broke up into icy fragments. The particles are still 'clean' from orbit dust because they continually grind against each other and break.
Uranus & Neptune are believed to have ___ cores surrounded by.....
Both planets are believed to have rocky cores surrounded by compressed water and liquid hydrogen and helium.
Water jets into space on ____
Enceladus
Saturn also has an icy moon called ___
Enceladus [which is very small, radium = 250 km)
which Galilean moon is a lot more promising to find life?
Europa
refer to more info on Ganymede >>>
Ganymede is dominated by the huge, dark, circular region which is the largest remnant of Ganymede's ancient crust. Darker areas of the moon are older; lighter areas are younger, tectonically deformed regions. The light white areas in and around craters indicate the presence of water ice. Large impacts create craters, filled in by ice from below the surface. The surface is not geologically active today.
the most famous feature on Jupiter is the...
Great Red Spot
all of the Galilean moons are icy except ____
Io
which moon is the most geologically active object in the solar system?
Io [has over 400 active volcanoes]
more info on why there are volcanoes on Io >>>
Io's surface is constantly altered by volcanoes spewing molten rock and Sulfur. On Earth, the energy for geological activity comes from radioactivity and heat of formation - its interior is still hot. However, Io's size is relatively small (~ our Moon), so it should have relatively little heat left from its formation period. There is a "land tide" of up to 100 feet!
refer to more info on Saturn's Moon: Titan >>>
It's BIG: Largest Moon of Saturn: 1.8 times the mass of Earth's Moon. It's cold, average T=-180 degrees C Titan's atmosphere is mostly Nitrogen with a substantial amount of Methane. There are organic molecules, but it is probably too cold for life to have evolved.
Jupiter also has dark ____. which are comprised of?
Jupiter also has dark rings, comprised mainly of dust, not ice like the rings of Saturn. They were discovered by Voyager in the late 1970s. [pic: Jupiter's Faint Rings]
refer to info on jupiter >>>
Jupiter is by far the most massive planet in the solar system (it contains about 2/3 of the solar system mass outside the Sun). It has the largest radius of any solar system planet, and it rotates the fastest (once every 10 hours). It has at least 63 moons. It has no solid surface. In many categories, Jupiter is the most extreme case.
how often is jupiter's rotation? what does this rotation do to the planet?
Jupiter rotates very quickly, completing a rotation every 10 hours. This rapid rotation drives high speeds winds and storms. Different colors correspond to different temperatures, chemical compositions, and heights. (Great Red Spot-Phosphorus)
due to Jupiter's rapid rotation, describe its atmosphere.
Owing to its rapid rotation, Jupiter has a very turbulent atmosphere, which is composed mostly of methane and ammonia (both hydrogen rich).
refer to info on Io's volcanoes >>>
Plumes from the volcano Prometheus rise up hundreds of km above Io. Prometheus has been active in every image taken of Io since the Voyager flybys of 1979.
refer to info on Saturn >>>
Saturn is 9.5AU from the Sun. It has the lowest density of any planet 687 kg/m3, less than that of water! Saturn is big, about 95 Earth masses. The outer atmosphere is very cold, ~100K= -280 oF. The composition of Saturn is similar to that of Jupiter, 96% H, 4% He. Saturn also rotates rapidly, once every 10 hours or so. Saturn's weather is like that on Jupiter, although the contrast between different bands is much less, and the wind speeds are lower.
small satellites can have what effect on saturn's rings?
Small satellites can cause some of the rings to ripple or to have braided structure.
what are the four Galilean moons? where are they located?
The Galilean moons are the four largest moons of Jupiter—Io, Europa, Ganymede, and Callisto.
refer to pic of Saturn's North Pole Hexagon >>>
The Mystery Hexagon on Saturn
Describe the Great Red Spot: how old is it? what exactly is it? what is the persistence of the red spot?
The Spot is at least 200 years old. It is basically a giant hurricane, roughly three times the size of Earth, with wind speeds >300 mph. Smaller features are also evident. Presumably the persistence of the Great Red Spot is related to the fact that it never comes over land, as in the case of a hurricane on Earth, and that it is driven by Jupiter's internal heat source.
List the giant planets.
The giant planets are Jupiter, Saturn, Uranus, and Neptune
why are there volcanoes on Io?
The heating source turns out to be Jupiter's gravity, which compresses Io as it orbits. Io has a slightly eccentric orbit so that its distance from Jupiter changes in time, and the gravitational force on Io changes also. The changing gravity results in a changing compression on the moon.*
refer to pic/info on Life in the Subsurface Lake Vostok, Antartica? >>>
The lake was drilled into by Russian scientists in 2012. The lake water itself may have been isolated for 15 to 25 million years. In 2013, a team of Russian scientists claimed to have completed the longest ever ice core of 3,623 m and pierced the ice shield to the surface of the lake. As soon as the ice was pierced, water from the underlying lake gushed up the borehole. Living micro-organisms have potentially been found in Lake Vostok's deep ice core drillings. This would suggest the presence of a deep biosphere utilizing a geothermal system of the bedrock encircling the subglacial lake. There is optimism that microbial life in the lake may be possible despite high pressure, constant cold, low nutrient input, potentially high oxygen concentration and an absence of sunlight. Jupiter's moon Europa and Saturn's moon Enceladus may also harbor lakes or oceans below a thick crust of ice. Any confirmation of life in Lake Vostok could strengthen the prospect for the presence of life on icy moons.
refer to info on difference between the giant planets & earth >>>
The radii are between about 4 and 11 times that of Earth. The masses are between 14 and 318 times that of Earth. However, the densities are low, between 0.7 and 1.8 grams/cc, and the albedos are high (highly reflective of light). The planets are composed of light elements, mostly Hydrogen and Helium. The composition of the giant planets, especially Jupiter, is close to that of the Sun. The external structures of these planets is completely different from that of the Earth. In particular, there is no hard surface. These planets are relatively far from the Sun (> 5 AU), so heating by the Sun is not a big factor.
what do the range of colors on Io result from?
The range of colors results from surface deposits of sulfur ejected from Io's numerous volcanoes.
refer to pic/info on the seasons of uranus >>>
The rotation axis of Uranus is inclined by about 90 degrees relative to its orbital plane. This gives rise to highly exaggerated seasons. Orbital Period of 84 years.
refer to more info on Callisto >>>
The series of faint, concentric rings that cover much of this image is the result of a huge impact that created the impact basin Valhalla. Valhalla dominates the Jupiter-facing hemisphere of this frozen, geologically inactive world. It is speculated that there is a subsurface ocean.
refer to even more info on Io's volcanoes >>>
There are many active volcanoes on Io, plus mountain ranges. No ice on surface, even though the surface temperature is T=100K or -170 degrees C! Several volcanoes produce plumes of sulfur and sulfur dioxide that climb as high as 500 km (300 mi) above the surface.
refer to more info on jupiter's interior >>>
There is no way to directly study the deep interior parts, we rely on computer models. The interior should be hot (35,000 K), with a solid rocky core, possibly surrounded by liquid. The solid rocky core is estimated to have a mass of ~10-20 times the Earth mass. A solid core is needed in order to have enough gravity to attract the light gases later on. The gaseous outer atmosphere surrounds molecular and liquid metallic hydrogen and helium. The composition of the planet overall is very similar to the Sun, 90%H, 10%He.
refer to more info on the Outer Gas Giants: Uranus and Neptune >>>
They are each about 4 times the diameter of the Earth, and about 15 times more massive than the Earth. They are made up mostly of H and He, ice, and some heavier elements. Both planets appear blue-green because of the Methane mixed in with the Hydrogen. The weather patterns are much less apparent than on Jupiter. Solar heating is not important since they are far from the Sun, and very cold.
saturn's rings consist of....
They consist of fragments of ice and ice-covered rocks from 1 cm-10 m in size. The Main rings extend out 100,000 km, yet are less than 100 m thick!
upwelling water and tidal stresses causes what to happen on Europa?
This image of Europa shows smooth plains of ice, mineral ridges deposited by upwelling water, and numerous fractures believed to be caused by tidal stresses.
refer to pic of surface features on europa >>>
This region of Europa's surface shows the jumbled, stressed features common to the surface, as well as direct indications of liquid water activity underground.
what impact does Tidal Flexing have on Europa's interior?
Tidal flexing kneads Europa's interior and gives the moon a source of heat, possibly allowing its ocean to stay liquid while driving subsurface geological processes.
Saturn has 1 very large moon called ____ . It also has 10 moderate size moons, and a few dozen much smaller ones.
Titan
refer to more info on Enceladus >>>
a) Cassini view of the two distinct landscapes on Enceladus, one heavily cratered, the other nearly crater-free. The blue "tiger stripes" are believed to be due to upwelling of liquid water that froze at the surface. b) The ridges are thought to be created by tectonic flows. The inset shows ice boulders. Enceladus seems to have liquid water under its icy surface
Europa also may have ..... underneath the surface
an ocean of liquid water
the giant planets' masses are ____ than earth, but their densities are ____
bigger, lower
the outermost Galilean satellite is ____
callisto
saturn has the lowest ___ of any planet, less than that of water!
density
the next moon, Ganymede is significantly lower in ____
density
three of the Galilean moons have low densities, which indicate....
each contains a thick layer of water and ice.
the Galilean moon, ____ has a very smooth icy surface
europa
Ganymede is roughly half ___ and half ___
ice, rock
numerous craters pockmark Callisto's ___ ____
icy surface
extremophiles, which is a type of organism, exist ____ from the sun. how?
independently; convert the heat, methane, and sulfur compounds provided by black smokers into energy through a process called chemosynthesis. More complex life forms, such as clams and tubeworms, feed on these organisms.
what is the most massive planet in the solar system?
jupiter
Io is one of ____ moon
jupiter's
Ganymede is the ____ moon in our solar system
largest
the giant planets are primarily composed of ...
light elements: mostly hydrogen & helium
Callisto is almost the same size as ___
mercury
on Titan, there are lakes of liquid ____, which are seen to....
methane; evolve over time
the darker areas on Ganymede are ____, lighter areas are ___
older, younger
the 8 planets orbit in nearly the same ____ in space
plane (ecliptic)
refer to another pic of Saturn's Icy Moon -- Enceladus >>>
refer to pic of Saturn's Icy Moon -- Enceladus >>>
refer to pic of Saturn's Icy Moon -- Enceladus >>>
refer to pic of Saturn's Icy Moon -- Enceladus >>>
The most obvious feature of Saturn is its large ____ system, which has been known for more than 300 years.
ring
The 4 Galilean moons have small ___ or ___ cores
rocky or iron cores.
describe jupiter's rotation. what does this lead to?
rotates very quickly (once every 10 hours) ; generates a lot of wind and weather
the surface of Io has no impact craters, which must imply....
that it's surface is young
the light white areas in and around the craters indicate...
the presence of water ice
the composition of the giant planet, Jupiter is closest to that of...
the sun
Titan is the only moon in our solar system with a .....
thick atmosphere.
what is the astronomer's goal when exploring objects in the solar system?
to find life
the surface of Io is ____ that of any other solar system
unlike
what are the outer gas giants?
uranus & neptune
there are active ____ on Io
volcanoes
europa has a lot of _____. refer to pic >>>
water; [pic: all of the water on europa compared to all the water on earth]
saturn's rings are super ___ & ___ and spread out over time
wide & thin
