1 Comparative Planetology of the Outer Planets Chapter 18 (150+ slides) A Travel Guide to the Outer Planets • Hydrogen-rich atmospheres • belt-zone circulation • shallow atmospheres • interiors mostly liquid hydrogen • Large satellite systems Jupiter
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50 moons & 14 provisional moons are known of for Jupiter
Four largest moons discovered by Galileo are know as The Galilean Moons
Io Europa Ganymede Callisto
Jupiter and two moons
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Callisto: The Ancient FaceTidally locked to Jupiter, like all of Jupiter’s moons.
Av. density: 1.79 g/cm3
composition: mixture of ice and rocks
Dark surface, heavily pocked with craters.
No metallic core: Callisto never differentiated to form core and mantle.
No magnetic field.
Layer of liquid water, ~ 10 km thick, ~ 100 km below surface, probably heated by radioactive decay.
Jupiter CallistoJupiter
Callisto is surrounded by an extremely thin atmosphere composed of carbon dioxide and probably molecular oxygen. Investigation revealed that Callisto may possibly have a subsurface ocean of liquid water at depths less than 300 kilometers. The likely presence of an ocean within Callistoindicates that it can or could harbor life. However, this is less likely than on nearby Europa. Callisto has long been considered the most suitable place for a human base for future exploration of the Jupiter system since it is furthest from the intense radiation of Jupiter.
Ganymede: A Hidden PastLargest of the 4 Galilean moons. Av. density = 1.9 g/cm3
Close to Jupiter should be hit by many meteoroid impacts;
but few craters visible.
Active surface; impact craters rapidly erased.
Jupiter
The Surface of Europa
Cracked surface and high albedo (reflectivity) provide further evidence for geological activity.
Jupiter
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The Interior of EuropaEuropa is too small to retain its internal heat
Heating mostly from tidal interaction with Jupiter.Core not molten No magnetic field.
Europa has a liquid water ocean ~ 15 km below the icy surface.
Jupiter EuropaJupiter
Ganymede is composed of approximately equal amounts of silicate rock and water ice. It is a fully differentiated body with an iron-rich, liquid core, and an internal ocean that may contain more water than all of Earth's oceans combined. Its surface is composed of two main types of terrain. Dark regions, saturated with impact craters and dated to four billion years ago, cover about a third of the satellite. Lighter regions, crosscut by extensive grooves and ridges and only slightly less ancient, cover the remainder. The cause of the light terrain's disrupted geology is not fully known, but was likely the result of tectonic activity due to tidal heating.
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Io: Bursting EnergyMost active of all Galilean moons;
no impact craters visible at all.
Over 100 active volcanoes!
Av. density = 3.55 g/cm3
Interior is mostly rock.
Activity powered by tidal interactions
with Jupiter.
Jupiter Jupiter - Io
Io's volcanism is responsible for many of its unique features. Its volcanic plumes and lava flows produce large surface changes and paint the surface in various subtle shades of yellow, red, white, black, and green, largely due to allotropes and compounds of sulfur.
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With over 400 active volcanoes, Io is the most geologically active object in the Solar System. Several volcanoes produce plumes of sulfur and sulfur dioxide that climb as high as 500 km (300 mi) above the surface. Io's surface is also dotted with more than 100 mountains that have been uplifted by extensive compression at the base of Io's silicate crust. Io is primarily composed of silicate rock surrounding a molten iron or iron-sulfide core. Most of Io's surface is composed of extensive plains coated with sulfurand sulfur-dioxide frost.
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• Formed from cold gas in the
outer solar nebula, where
ices were able to condense.
• Rapid growth
• Soon able to trap gas directly through gravity
• Heavy materials sink to the center
• In the interior, hydrogen becomes metallic (very good
electrical conductor)
• Rapid rotation strong
magnetic field
• Rapid rotation and large size belt-zone cloud pattern
• Dust from meteorite impacts onto inner moons trapped to form ring
• Equatorial Radius:– 1185 km– 0.18 times Earth’s radius– 0.02 times Jupiter’s radius
• Mass– 0.0022 times Earth’s mass– 0.000007 times Jupiter’s mass
• Distance from Sun– 39.44 AU (Jupiter is 5.2 AU)
• Rotation Period– 247.7 years (Jupiter is 11.867 years)
Pluto is NOT a Planet• Virtually no surface features visible from Earth.
• ~ 65 % of size of Earth’s Moon.
• Highly elliptical orbit; coming occasionally closer to the sun than Neptune.
• Orbit highly inclined (17o) against other planets’ orbits
Neptune and Pluto will never collide.
• Surface covered with nitrogen ice; traces of frozen methane and carbon monoxide.
• Daytime temperature (50 K) enough to vaporize some N and CO to form a very tenuous atmosphere.
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Definition of a Planet• Planets: The eight worlds starting with Mercury
and moving out to Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
• Dwarf planets: Pluto and any other round object that "has not cleared the neighborhood around its orbit, and is not a satellite."
• Small solar system bodies: All other objects orbiting the sun.
Pluto’s Moon Charon
Hubble Space Telescope image
Discovered in 1978;
about half the size and
1/12 the mass of
Pluto itself.
Tidally locked to
Pluto.
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Pluto and CharonOrbit highly inclined against orbital plane.
From separation and orbital period:
Mpluto ~ 0.2 Earth masses.
Density ≈ 2 g/cm3
(both Pluto and Charon)
~ 35% ice and 65% rock.
Large orbital inclinations → Large seasonal changes on
Pluto and Charon.
The Origin of Pluto and CharonProbably very different history than neighboring Jovian planets.
Older theory:
Pluto and Charon members of Kuiper belt of small, icy objects. Collision between Pluto and Charon may have caused the peculiar orbital patterns and large inclination of Pluto’s rotation axis.
Pluto and Charon formed as moons of Neptune, ejected by interaction with massive planetesimal. Mostly abandoned today since such interactions are unlikely.
• Miranda (Uranus)• Titan (Saturn)• Io (Jupiter)• Europa (Jupiter)• Callisto (Jupiter)• Ganymede (Jupiter)• Moon (Earth)• Phobos (Mars)
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October 7, 2002NASA's Hubble Space Telescope has measured the largest object discovered in the solar system since the discovery of Pluto 72 years ago. Approximately half the size of Pluto, the icy world 2002 LM60, dubbed "Quaoar" (pronounced kwa-whar) by its discoverers, is the farthest object in the solar system ever to be resolved by a telescope. It was initially detected by a ground-based telescope, as simply a dot of light, until astronomers aimed the powerful Hubble telescope at it.
Sedna
This artist's concept shows the planet catalogued as 2003UB313 at the lonely outer fringes of our solar system. Our Sun can be seen in the distance. The new planet, which is yet to be formally named, is at least as big as Pluto and about three times farther away from the Sun than Pluto. It is very cold and dark. The planet was discovered by the Samuel Oschin Telescope at the Palomar Observatory near San Diego, Calif., on Jan. 8, 2005. Image credit: NASA/JPL-Caltech