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AS101 Week 11 Lecture 1.docx

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Wilfrid Laurier University
Patrick Mc Graw

AS101 Week 11 Lecture 1 Common Characteristics of Jovian Planets  Larger than terrestrial planets.  Contain a lot more hydrogen and helium, and hydrogen-containing compounds like water, ammonia, methane (a.k.a. “ices”)  Multiple satellites (some with atmospheres/oceans.)  All have rings made up of icy/rocky debris. (Saturn's are the most prominent.)  In summary, you could almost say that it's as if each one of the Jovian planets forms its own miniature solar system. Jupiter  Distance from Sun: 5.2 au  Orbital period: 11.86 years  Rotation period: 10 hours  Surface temp (top of cloud layer): -108 C  90%hydrogen, 10% helium, less than 1% other stuff. Moons of Jupiter  The 4 Galilean moons  IO  Europa  Ganymede  Callisto Moons of Jupiter: Other Moons  Many smaller objects (less than a few hundred km across) orbit Jupiter.  Closer than the Galilean four include Amalthea, Metis, Adrastea, Thebe. Jupiter: Internal Structure  Metallic Hydrogen: Under high  pressures, hydrogen becomes an  electrical conductor and behaves  like a liquid metal.  Liquid metal creates an extremely  strong magnetic field compared  to Earth.  Not naturally occurring on Earth, but under high pressures you can duplicate this behaviour  Helps explain why Jupiter has such a high magnetic field Jupiter's Aurora  Jupiter has an aurora because of its magnetic field Jovian Weather: Belt and Zone Ciculation  Belts: darker bands of lower pressure.  Zones: lighter bands of higher pressure.  Patterns of wind can be understood based on the interaction of convection and the planet's rotation, much as on Earth.  Convection: a pattern of circulation in which a fluid (or gas) heated from below rises, then loses some of its heat and sinks. o Convection is combined with planets rotation o Convection: hotter gas to rise, cooler gas to sink Earth's and Jupiter's Weather Similarities  Wind patterns created by the combination of convection, pressure differences and the planet's rotation.  Winds spiral around high and low pressure areas due to the Coriolis effect.  Large-scale bands parallel to latitude lines, smaller systems within the global pattern. Earth's and Jupiter's Weather Differences  Jupiter rotates faster, so the effect of rotation is stronger.  Jupiter is more symmetrical: no continents, oceans, mountain ranges to break up the pattern. (And weaker seasonal changes.)  Main energy source on Earth is heat from the sun. On Jupiter, weather patterns are mostly driven by heat escaping from the planet's interior.  Seasonal changes in Jupiter are weaker Jupiter's Hot Interior  Infrared observations show both Jupiter and Saturn emit noticeably more energy than they absorb from the sun.  Both are gradually cooling off--- still losing the heat they gained in the process of forming.  Estimated temp. at Jupiter's core: 25,000 K.  Not hot enough to start a fusion reaction and become a star, but not far from the borderline.  Jupiters energy balance is not in balance Saturn  Distance from Sun: 9.6 au  Orbital period: 29.5 years  Rotation period: 10.6 hours  Surface temperature: - 139 C  Composition: about 96% hydrogen, 3% helium. (less helium than Jupiter or the Sun...) Saturn's Moons  More than 62 known moons  Largest moon, Titan, is larger than Mercury.  Titan is the only moon in the solar system with a significant atmosphere  Titan’s atmosphere is about 1.5x as thick as Earth’s atmosphere Jupiter and Saturn  Together, Jupiter and Saturn add up to 92% of the total planetary mass in the solar system. o aside from the sun
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