The Giant PlanetsThe Giant Planets Jupiter, Physical AttributesJupiter, Physical Attributes! Mean distance from the Sun ≈ 5.2 AU! Radius ≈ 11 × REarth

! Mass ≈ 315 × MEarth

! Huge! Jupiter is 21/2 times more massive than all other planets combined.

! Density = Mass÷Volume ≈ 1.3 gm/cm3

! Low compared to the ≈ 5 gm/cm3 of terrestrial planets; implies very different composition

! Must contain low density substances: H and compounds—water, ammonia, and methane

! Element abundance similar to the Sun; Spectra show presence of helium as well as hydrogen, water, ammonia, and methane

! Atmosphere thickens with depth as weight compresses underlying material, changing gradually from gas to liquid

! Below the atmosphere is a sea of liquid H! Below that, a zone of metallic hydrogen! Core of rock and iron: gravitational field and shape of

planet suggest 4% mass in core

Jupiter, AtmosphereJupiter, Atmosphere

! Very Hot Interior! From measurements of heat loss! Theoretical models

! Loses more heat than it gets from the Sun?! Original heat of formation! Continued gravitational compression

! Heat drives convective motions in atmosphere: gas rises, flows along the surface and sinks back

! Cloud motions show rapid rotation of planet: approximately 10 hours! Surface exhibits strong cloud belts - result of convection inside and

Corio lis Effect! Other atmospheric features include the Great Red Spot, (a huge

atmospheric vortex) and smaller, fainter vortices! Clouds contain water, ice and ammonia! Cloud colors probably from complex molecules

! Strong magnetic fields ! Caused by electric currents sustained by

! rapid rotation! convection in deep interior! Metallic hydrogen; good conductor of electricity

! Steers solar wind particles to polar regions to cause auroras! Produce radio waves in the 3 – 75 cm range

The Jovian SystemThe Jovian System! A mini-Solar System;

! 16 satellites

! Most lie in equatorial plane and orbit in the same direction

! Four largest moons: the Galilean satellites! Io, Europa! Ganymede, Callisto

! All locked in synchronous rotation

! All rich in silicates! rocky material

! All except Io rich in iceFaint, thin, ring system

discovered in 1977

The Four Galilean Satellites of JupiterThe Four Galilean Satellites of JupiterThe Four Galilean Satellites of Jupiter IoIo

! Looks like a pizza, mostly orange-colored, with white, yellow and dark blotches

! Heated by strong tidal forces exerted on it by Jupiter and the other Galilean satellites

! Erupting sulfur volcanoes: ! 10,000 tons/sec

! Feeds about one ton every second into the, a doughnut shaped ring of plasma around its orbital path

! Black spots are volcanic vents

ClosestClosest--Ever Ever Pictures of IoPictures of Io

October 10, 1999: While just 671 km above Io, Galileo snapped a high-resolution picture of a lava field near the center of an erupting volcano.

EuropaEuropa! Smooth icy surface

! cracks on surface! Heated and partially

resurfaced! few impact craters

! Heating due to gravitational tidal forces of Jupiter and outer satellites

! Melts ice and causes cracks in the surface

! Ocean of ice, continually recycled a la plate tectonics on Earth

Sulfuric Acid Found onSulfuric Acid Found on EuropaEuropa

Sulfuric acid, a corrosive chemical found on Earth in car batteries, exists on the frozen surface of Jupiter's icy moon Europa.

! Ganymede!Largest moon in the Solar System

!Heavily cratered, icy surface

!Light-colored grooved terrain (old plate tectonics)

!Dark, circular island of ancient crust (far side)

! Callisto! Size of Mercury

! Heavily cratered, ancient icy surface. Ocean of water under the ice

! No grooved terrain

!No plate tectonics ever

! Large impact basin; concentric rings up to 3,000 km in diameter

Why are Callisto and Ganymede so different?