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Ch 7--The Outer Planets. What Do You Think. Is Jupiter a “failed star” or almost a star? What is Jupiter’s Great Red Spot? Does Jupiter have continents and oceans? Is Saturn the only planet with rings? Are the rings of Saturn solid ribbons?. Astronomical Telescopes. Jupiter.
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Ch 7--The Outer Planets ASTR103, GMU, Dr. Correll
What Do You Think • Is Jupiter a “failed star” or almost a star? • What is Jupiter’s Great Red Spot? • Does Jupiter have continents and oceans? • Is Saturn the only planet with rings? • Are the rings of Saturn solid ribbons? ASTR103, GMU, Dr. Correll
Astronomical Telescopes ASTR103, GMU, Dr. Correll
Jupiter ASTR103, GMU, Dr. Correll
Jupiter Outer Layer • Rapid rotation generates dynamic atmosphere • The great red spot • a “hurricane” lasting for centuries • Differential rotation at different latitudes causes colored cloud bands ASTR103, GMU, Dr. Correll
Jupiter’s Atmosphere • Spectroscopy from earth and spacecraft reveal • 86% hydrogen • 13% helium • traces of other simple compounds • methane • ammonia • water vapor ASTR103, GMU, Dr. Correll
Jupiter’s Atmosphere • Convection--movement of material from hotter to cooler regions • just as we saw in the Earth’s mantle • and we’ll see later in the Sun ASTR103, GMU, Dr. Correll
Jupiter’s Interior • Atmosphere--about 150 km of hydrogen, helium and trace gases • Liquid Hydrogen mantle--60,000 km • lower 40,000 km is liquid metallic hydrogen which is electrically conductive, generating the planet’s magnetic field--about 20,000 time stronger than Earth’s • Terrestrial protoplanet core--inner 10,000 km radius, about 50% larger than the Earth! ASTR103, GMU, Dr. Correll
Jupiter’s Moons • Jupiter has at least 16 moons--typical for a large planet • Four largest were discovered by Galileo--the Gallilean moons • Io • Europa • Ganymede • Callisto ASTR103, GMU, Dr. Correll
Jupiter’s Moons ASTR103, GMU, Dr. Correll
Io • Tidal forces generate heat and volcanic activity • Rich in sulfur and sulfur dioxide, hence the yellowish color ASTR103, GMU, Dr. Correll
Europa • Ice and rock crust • Tidal forces heat the moon, making it likely that liquid water is abundant under the ice crust • fracture lines in crust support this theory ASTR103, GMU, Dr. Correll
Ganymede • Largest Jovian moon • Iron-rich core • ice and rock mantle • week magnetic field • thin atmosphere ASTR103, GMU, Dr. Correll
Callisto • Similar to Ganymede--icy and rocky • But, no iron-rich core • Geologically inactive ASTR103, GMU, Dr. Correll
Jupiter’s Rings • Rings comprised of small particles of dust and ice ASTR103, GMU, Dr. Correll
Saturn ASTR103, GMU, Dr. Correll
Saturn • Very similar to Jupiter in elemental makeup and dynamic structure ASTR103, GMU, Dr. Correll
Saturn • Strong magnetic field creates auroral activity as on Earth and Jupiter ASTR103, GMU, Dr. Correll
Saturn’s Rings • Composed of ice, dust and rock • Different rings separated by gaps • due to resonances with gravity of Saturn’s moons • first discovered by Cassini in 1675 ASTR103, GMU, Dr. Correll
Saturn’s Moons • Of Saturn’s 22 known moons, only 7 are spherical • the rest probably captured asteroids • Has a dense atmosphere of nitrogen gas • 4 times denser than Earth’s • rich in primitive organic molecules ASTR103, GMU, Dr. Correll
Uranus and Neptune ASTR103, GMU, Dr. Correll
Uranus and Neptune--Interiors ASTR103, GMU, Dr. Correll
Planetary Magnetic Fields • Planetary magnetic fields don’t always line up with rotation axis--and probably change orientation with time ASTR103, GMU, Dr. Correll
Rings and Moons of Uranus • A common feature of large planets ASTR103, GMU, Dr. Correll
Neptune’s Discovery • 1781--Uranus discovered • 1840--Uranus orbit not following predicted path according to Newtonian gravity • 1840-1846--John Adams and Erbain Leverrier predicted the location of an undiscovered planet • 1846--Neptune discovered by Johann Galle at predicted location • Newton’s theory of gravity vindicated! ASTR103, GMU, Dr. Correll
Pluto ASTR103, GMU, Dr. Correll
Pluto and Charon • Pluto is about 8 times as massive as its moon Charon • Similar in composition • rock and ice • No discernable features • Mutually synchronous rotation! ASTR103, GMU, Dr. Correll
What Do You Think • Is Jupiter a “failed star” or almost a star? • Jupiter has 75 times too little mass to shine as a star • What is Jupiter’s Great Red Spot? • The great red spot is a long-lived, oval cloud circulation similar to a hurricane on Earth • Does Jupiter have continents and oceans? • No, Jupiter is comprised mainly of a dense mantle of liquid hydrogen and helium. There is a solid core at it’s center. • Is Saturn the only planet with rings? • No, Four planets (Jupiter, Saturn, Uranus, and Neptune) have rings • Are the rings of Saturn solid ribbons? • Saturn’s rings are all comprised of thin, closely spaced ringlets of ice and dust particles ASTR103, GMU, Dr. Correll
Questions for review • Describe the planet Jupiter, it’s cloud tops, interior layers, magnetic fields and moons. ASTR103, GMU, Dr. Correll