Intro to Solar System

Intro to Solar System Jovian Planets and Moons 1

Jovian Planets

and Moons


Jovian Planets

primitive, look much as they did at time of formation gas giants, completely different than the terrestrial planets


Voyager Project, JPL, NASA

Jupiter • largest most massive of all

• size 140,00 km 11 Earths across • mass - 300 times that of Earth • density 1300 kg/m3

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What makes the colors in Jupiter's clouds? With a mean temperature of 120 degrees Kelvin (-153 degrees Celsius) and a composition dominated by hydrogen (about 90%), and helium (about 10%) with a smattering of hydrogen compounds like methane and ammonia, the blue, orange, and brown cloud bands and the salmon colored "red" spot are hard to explain. Trouble is -- at the cool cloud temperatures Jupiter's atmospheric constituents should be colorless! Some suggest that more colorful hydrogen compounds well up from warmer regions in the atmosphere, tinting the cloud tops. Alternatively, compounds of trace elements like sulfur may color the clouds. Jupiter's colors do indicate the clouds' altitudes, blue is lowest through red as highest. The dark colored bands are called belts and the light colored ones zones. In addition to the belts and zones, the Voyager missions revealed the presence of intricate vortices visible, for example, in this 1979 image from the Voyager I flyby. Centuries of visual observations of Jupiter have revealed that the colors of its clouds are ever changing. 2.5 times mass of all planets totaled Jovian planets are made of much different stuff!


Jupiter - Composition

hydrogen, helium - liquid and gaseous gases that have been there since formation

temperature: 130 K escape speed: 60 km/sec

even hydrogen can’t get away!


Jupiter - “Surface” there is NO surface !!

convective flow in the atmosphere light regions: zones - tops of high pressure regions dark regions: belts - descending areas of low pressure

convective flow tells us the interior is HOT!


Jupiter - “Surface”

rotation: 10 hours differential rotation => a fluid cloud speed: 43,00 km/hr

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26,000 mi/hr speed stretches the clouds into belts and zones


Great Red Spot

permanent storm: observed in 1630 cooler than surrounding zone, is raised a few km above it rotates counterclockwise, 7 day period

NASA


Jupiter - Atmosphere

Galileo - Probe Entry Point

82% Hydrogen 18% Helium ammonia ice crystals, liquid ammonia, water ice

1000 km thick

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much like the Sun’s composition


Jupiter - Internal Structure • low density and atmospheric composition

materials like the Sun

• radiates away more energy than it receives

hot interior (heat from formation)


Jupiter - Interior Structure differentiated outer layer: molecular hydrogen liquid hydrogen density pressure liquid metallic hydrogen

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pressure so great that protons and electrons separate


Jupiter - Interior Structure core: heavy elements (rocky?) temperature 10 x Earth

magnetic field: HUGE - 10 x Earth’s expected due to rapid rotation, metallic liquid core


Jupiter - Moons

Io - 3500 kg/m3

Europa - 3000 kg/m3

Ganymede - 1900 kg/m3

Callisto - 1800 kg/m3

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: This composite image features classic portraits of members of one of the Solar System's most prominent families - Jupiter and its four large "Galilean" moons. Starting from the top the moons are Io, Europa, Ganymede, and Callisto. The top-to-bottom order is also the order of increasing distance from Jupiter. These are big moons indeed which attend the largest planet. The smallest of the lot, Europa, is the size of Earth's moon while Ganymede is the largest moon in the Solar System. In fact, Ganymede with a diameter of 3,100 miles, is larger than the planets Mercury and Pluto. The swirling Great Red Spot appears at the edge of Jupiter. A hurricane-like storm system that has persisted for over 300 years, two to three earths could fit inside it. Battered Callisto's image was recorded during the 1979 flyby of Voyager. The other portraits were taken by the Galileo spacecraft which began exploring the Jovian system in 1995. : Galileo Project, Voyager Project, JPL, NASA


Io

•thin sulfur dioxide atmosphere •sodium emissions •volcanic eruptions •lava lakes

surface of Io - youngest in the Solar System

Galileo Project, JPL, NASA

(no impact craters)

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The surface of Io is changing even as we watch. The inset frame of Jupiter's most active moon was taken by the robot spacecraft Galileo in April. Just last month the larger image was taken. The new large black spot reveals that a volcano named Pillan Patera has been erupting during the interim. A vast moonscape roughly the size of Arizona has just been covered by some dark material. What is this material? It's composition remains unknown although it is certainly different in color from the red material seen surrounding volcano Pele on the upper left. Galileo Project, JPL, NASA 1 million years old



Europa •water ice •filled in fractures •smoothest surface •devoid of craters •not primitive

beneath the crust ???

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This bull's-eye pattern marks the impact of a mountain-sized comet or asteroid on the icy surface of Jupiter's moon Europa. Recorded by the Galileo spacecraft in April of this year, the composite false color image clearly reveals the telltale concentric fractures which cover about 86 miles - roughly equivalent to the Island of Hawaii. The fat reddish and finer blue-green lines overlay the impact fractures and must therefore be younger surface features formed after the impact. The dark red color may be the result of a a relatively dirty water-ice mixture. The possibility of liquid water below the ice has fueled speculation that life may exist on this large and distant moon. Galileo Project, JPL, NASA


Europa


nearly the same size as our Moon

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What mysteries might be solved by peering into this crystal ball? This crystal ball is quite unusual because it is actually a moon of Jupiter, the crystals are ice-crystals, and the ball is not only dirty and opaque but cracked beyond repair. Nevertheless, speculation is rampant that oceans exist under these tortured ice-plains that could support life. Europa, the smallest of Jupiter's Galilean moons, was photographed last month in natural color by the robot spacecraft Galileo, now in orbit around Jupiter. The brown patches are what one might think: dirt -- tainting an otherwise white ice-crust. Europa, nearly the same size as Earth's Moon, similarly keeps one face toward its home planet. The hemisphere of Europa shown above is the one that always trails. Why is Europa's surface the smoothest in the Solar System? Where are Europa's craters? Galileo Project, JPL, NASA


cracks icy crust is thin interior was once hot

Europa - Conamara Region Galileo Project, JPL, NASA

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The Galileo Europa Mission has planned eight close fly-bys frozen moon. The first close encounter of this extended mission occurred last December and the next will occur in February. The above enhanced color picture shows a small region of Europa's Conamara region. The white and blue colors highlight regions covered by ice dust from the collision that created the Pwyll Crater. Disconnected islands of ice are visible that have apparently rafted to new positions. Galileo Project, JPL, NASA



Impact Crater - Pwyll

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The impact crater Pwyll (a name from Celtic Mythology) is thought to represent one of the youngest features on the surface of Jupiter's moon Europa. A combination of color and high resolution black and white data from NASA's Galileo spacecraft was used to produce this view looking down on the crater with the sun illuminating the scene from the right. Pwyll's visible dark central region is about 24 miles in diameter, while brilliant white rays of debris blasted from the impact site extend outward for hundreds of miles. The white debris or ejecta clearly overlays everything else on the surface - indicating that this formation is younger than all surrounding features. Interestingly, the bright white color suggests a composition of fresh water ice particles. Does water in liquid form exist below Europa's icy surface? Galileo Project, JPL, NASA


Lightning on Jupiter


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Why is there lightning on Jupiter? Lightning is a sudden rush of electrically charged particles from one location to another. To create lightning, charges must first separate inside a cloud. On Earth, drafts of colliding ice and water droplets usually create this charge separation, but what happens on Jupiter? Many astronomers theorize that Jovian lightning is also created in clouds containing water ice. To help investigate this, the above photograph was taken in October by the Galileo spacecraft now orbiting Jupiter. Clouds are dimly lit by sunlight reflected off Jupiter's moon Io. The bright flashes appear to originate in active regions at the level where water clouds would exist, and illuminate an even lower cloud level containing ammonia. One thing is for sure: lightning on Jupiter is a lot brighter than lighting on Earth. The Galileo Project, NASA


Ganymede

The Galileo Project, NASA

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Where is the rest of the circle? Jupiter's largest moon Ganymede has some truly unusual terrain, including the pictured half circle above cut by nearly parallel curves. Full circles can be easily explained by impact craters, but partial circles imply that some resurfacing has occurred since the original impact. The diameter of the half circle is about 32 kilometers. Also of interest is a dense linear crater chain that cuts across the top of the half-circle. Mysteries like these are typically solved by the hard work of reconstructing a sequence of natural occurrences, which in this case may yield a better understanding of Ganymede's interesting past.


The Galileo Project, NASA

Jupiter’s Inner Moons

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The potato-shaped inner moons of Jupiter are lined-up in this mosaic "family portrait" of these tiny Jovian satellites. The individual images were recorded over the last year by NASA's Galileo spacecraft and are scaled to the moons' relative sizes. Left to right in increasing order of distance from Jupiter are Metis (longest dimension 37 miles), Adrastea (12 miles), Amalthea (154 miles), and Thebe (72 miles). All these moons orbit in the zone between Io and Jupiter's rings, are bombarded by high-energy ions within the Jovian magnetosphere, and are probably locked in synchronus rotation by Jupiter's strong gravity. Why are they shaped like potatoes? Like the asteroids and the diminutive moons of Mars, their own gravity is not strong enough to mold them into spheres. The Galileo Project, NASA


R. Beebe (NMSU), NASA

InfraRed Jupiter Note: the ring

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: An inner moon, an edge-on, planet-girdling ring, and high altitude cloud bands are visible in this mosaic of infrared images of gas giant Jupiter. The moon Metis, 25 miles wide and about 80,000 miles from the planet, is the bright spot at the upper right. Metis lies within Jupiter's faint, tenuous ring, and may be a source of ring material. Recorded on September 17th by the NICMOS instrument on board the Hubble Space Telescope, these pictures also emphasize atmospheric features high above the main jovian cloud deck. Methane gas in Jupiter's atmosphere absorbs the near infrared light causing deeper clouds to appear dark at these wavelengths. Clouds riding above most of the atmospheric methane are bright. The circular dark spot just above the brightest cloud band is an image artifact.

http://charon.nmsu.edu/

http://www.nasa.gov/

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