Lecture 18 4/10/2013 12:54:00 PM
Jovian Planets and their moons, Part I
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
In summary, you could almost say that it's as if each one of the
Jovian planets forms its own miniature solar system.
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: other moons:
o Many smaller objects (less than a few hundred km across)
o Closer than the Galilean four include Amalthea, Metis,
o Metallic Hydrogen: Under high pressures, hydrogen
becomes an electrical conductor and behaves like a liquid
o Liquid metal creates an extremely strong magnetic field
compared to Earth.
Jovian weather: Belt and Zone Circulation:
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.
Earths and jupiters 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
Large-scale bands parallel to latitude lines, smaller systems within
the global pattern.
Earths and jupiters 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
Jupiters 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.
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...)
Moons: o More than 62 known moons
o Largest moon, Titan, is larger than Mercury.
o Titan is the only moon in the solar system with a significant
Jupiter and Saturn are real giants:
Together, Jupiter and Saturn add up to 92% of the total planetary
mass in the solar system.
Jupiter and Saturn:
o Similar size and composition