Jupiter and its Moons Summary 1. At an average distance of over 5 AU, Jupiter takes nearly 12 years to orbit the Sun 2. Jupiter is by far the largest and most massive planet in the solar system being over 11x the size and 318x the mass of the Earth. Indeed Jupiter is more massive than all the other planets combined! 3. Jupiter has a much lower density than the Terrestrial planets since it is made mostly of gases and liquids 4. Jupiter receives less than 1/25 th of the radiation the Earth receives so its outer layers are very cold Jupiter has a Large Equatorial Bulge! 6.9% compared to the Earth s 0.3%! This is because Jupiter is made of a mixture of gas and liquid and rotates rapidly! Jupiter Rotates Differentially Jupiter from Earth Superior planet: best seen at opposition! 1
Jupiter from Space The winds in the belts and zones travel in opposite directions! Jupiter s weather patterns are driven by the release of internal heat via convection Convection: bulk moments of gases and liquids Jupiter in the Infrared (IR) The Great Red Spot a giant rotating storm in Jupiter s outer atmosphere! 2
The Motion of the Great Red Spot Smaller Storm Features White Ovals Brown Ovals Red Spot, Jr. and Baby Red Spot New Red Spots 3
Spot Interactions In Jun 2010 Jupiter s South Equatorial Belt Vanished! Also did this in the early 1970 s Chemical Composition of Atmosphere 86.2% molecular hydrogen (H 2 ) 13.6% atomic helium (He) 0.2% mixture of methane (CH 4 ), ammonia (NH 3 ), water (H 2 O) and hydrogen sulfide (H 2 S) Similar to the Sun! Hydrogen and Helium are colorless gases! The highly colored atmosphere comes from chemical reactions between the trace components of the atmosphere! These reactions are driven by the heat being released from the interior! Jupiter s Outer Layers Which layer is the great red spot associated with? 4
Which layer are white ovals associated with? Which layer are brown ovals associated with? The Galileo Mission The atmospheric entry probe parachuted into Jupiter s atmosphere Consisted of orbiter and atmospheric entry probe Returning measurements of chemical compositions and physical conditions 146 km below the surface the signal from the probe was lost due to the high temps and pressures 5
Energy Emission Energy received from Sun = energy reflected (albedo) + energy absorbed Absorbed energy is emitted out into space as heat (IR) Expect: energy emitted < energy received Jupiter emits twice as much energy as it receives from the Sun! Origin of excess energy? Internal heat! This is the same heat that drives the weather patterns and cloud chemistry! Jupiter is mostly made of liquid! Internal Structure Central rocky core surrounded by huge envelope of mostly hydrogen depth temp pressure Rocky core is 14-18x mass of the Earth Ice layer is 4x mass of the Earth Jupiter s magnetosphere is huge! The large amounts of liquid metallic hydrogen and its rapid rotation generates a very powerful magnetic field! 20,000x stronger than the Earth s 6
It has radiation belts like the Earth! One million times the volume of the Earth s magnetosphere! When charges particles spiral into the upper atmosphere they generate aurora! Jupiter has the most moons of any planet! 63 in total! Most are very small and are probably captured asteroids The largest are the 4 moons discovered by Galileo! The four Galilean Moons are of similar size to the smaller Terrestrial planets! 7
They all have synchronous rotations like the Moon! Bulk Properties Same side always faces Jupiter! The Galilean Moons and Jupiter are like a miniature solar system! Io is similar in size and density to the Moon! How much geological activity? Very low! Expected to have an ancient, heavily cratered surface like the Moon! 8
Io from Voyager 2 Flyby Galileo Image of Europa Highly colored surface covered with sulfur compounds! Like a rotten pizza! Not a single impact crater! The surface of Io is geologically young, even younger than the Earth! There must therefore be an extremely high level of geological activity! Source of geological activity? Volcanism! How can this be? Io is the most geologically active body in the solar system! 9
Tidal Forces Tidal Distortion The orbital periods of Io, Europa and Ganymede are in a 1:2:4 resonance! This elongates Io s orbit into an ellipse which in turn causes tidal distortion This flexing generates enormous amounts of internal heat which drives the volcanism A Volcanic Caldera on Io The volcanoes eject sulfur compounds from the interior which cover the surface 10
At any time there are many volcanoes erupting simultaneously! The eruptions on Io are more like Geysers than volcanoes! IR image Old Faithful Geyser Yellowstone National Park, WY Geothermal heat from the Earth converts water into steam which expands and blasts water above the surface! The eruptions on Io are probably powered by the rapid expansion of sulfur dioxide (SO 2 ) liquid into sulfur dioxide gas! Io Plasma Torus Europa is slightly smaller than the Moon and has a lower density It is mostly made of rock with a thin layer of ice on its surface Ionized debris spread along Io s orbit 11
Galileo Orbiter Image of Europa Again, we would expect an icy version of the Moon! Very smooth, icy surface with few impact craters Covered with cracks and dark meteoritic debris! Again, geologically younger than expected from size! Origin? Once again tidal flexing! Not as strong as in Io! Cracks are probably caused by the tidal flexing of suggesting is icy crust is very thin! Europa may have a subsurface ocean of water! Evidence: frozen icebergs on the surface 12
Basic Requirements for Life 1. Liquid solvent water 2. Raw materials for biological molecules - carbon 3. Energy source Sun, geothermal Europa has it all! 1. Water in the form of a sub-surface ocean 2. Carbon-rich nutrients from meteoritic debris which percolate down from the surface 3. Geothermal energy from tidal flexing One day we may send a submarine probe to explore Europa s subsurface ocean! Life on Europa? Life may be present beneath Europa s subsurface ocean! Life on Earth started in the oceans! Ganymede Ganymede s icy surface is older than Europa s The solar system s largest moon (larger than Mercury!) The only moon to have its own magnetic field! It has two kinds of terrain 13
The dark terrain is old and heavily cratered while the bright terrain is highly grooved with fewer craters! Ganymede s bright, grooved terrain Evidence for past tectonic activity! Callisto Callisto has a dark, ancient, heavily cratered surface with few signs of geological activity! It s like an icy version of the Moon! An icy version of the Moon! The Valhalla Impact Basin Dating the Ages of Icy Moons Geological age # impact craters Surface darkness Due to build-up of meteoritic debris Similar to Caloris on Mercury and the Oriental Basin on the far side of the Moon 14
Some of the smaller moon s of Jupiter Captured asteroids! 15