The Outer Planets

Chapter 23, Section 3

Jupiter: Giant Among Planets Jupiter has a mass that is 2 ½ times greater than the mass

of all other planets and moons combined If Jupiter had been about 10 times larger, it would have

become a star One rotation around its axis take 10 Earth hours The most striking feature of Jupiter is its Great Red Spot, it is

a cyclonic storm in the upper atmosphere Jupiter’s hydrogen-helium atmosphere also contains small

amounts of methane, ammonia, water, and sulfur compounds

Due to immense pressures within the atmosphere, Jupiter is thought to be a gigantic ocean of liquid hydrogen

Jupiter also has a faint system of rings surrounding the planet, not discovered until Voyager 1 flew past in 1979

Jupiter’s Atmosphere

Jupiter’s Moons Jupiter’s satellite system, consisting of 28 moons

discovered so far, looks like a mini solar system The four largest moons (Io, Europa, Ganymede,

and Callisto) were discovered by Galileo Io is one of three known volcanically active

bodies in our solar system (Neptune’s moon Triton is another)

The largest of the moons is Ganymede Europa is covered with ice and shows many

linear features Callisto is heavily cratered and greatly

resembles Earth’s moon

Jupiter and its Moons

Saturn: The Elegant Planet The most prominent feature of Saturn is its system of

rings Saturn’s atmosphere is very active, with wind speeds

up to 1500 kilometers per hour Large “cyclonic” storms occur in the atmosphere The main rings of Saturn (A and B) are very dense

and contain many “moonlets” that often collide with each other

Saturn’s faintest ring (E) is composed of very fine particles that are spread apart

Saturn’s satellite system consists of 31 moons (Titan is the largest and has an atmosphere that obscures its surface from view)

Saturn’s moon, Enceladus, was found to emit liquid geysers

Saturn and its Moons

Saturn’s Rings

Uranus: The Sideways Planet Instead of being generally perpendicular to

the plane of its orbit, Uranus’s axis of rotation lies nearly parallel with the plane of its orbit

Uranus has a set of at least nine distinct rings

Uranus has five large moons, and many smaller ones, that are very varied in their geology: deep canyons, linear scars, large-smooth areas on otherwise cratered surfaces

Uranus

Neptune: The Windy Planet Winds exceeding 1000 kilometers per hour

encircle Neptune, making it one of the windiest places in the solar system

It has an Earth-size storm called the Great Dark Spot

There are white, cirrus-like clouds that occupy a layer about 50 kilometers above the main cloud deck, thought to be frozen methane

Triton, Neptune’s largest moon, exhibits retrograde motion, indicating that it formed separately from Neptune and was gravitationally captured

Neptune

Pluto: Planet X Pluto lies on the fringe of the solar system, almost 40

times farther from the sun than Earth Because of its great distance, and slow orbital

period, it takes Pluto 248 Earth-years to orbit the sun Pluto’s orbit is highly eccentric, causing it to

occasionally travel inside the orbit of Neptune, where it resided from 1979 through February 1999

In 1978, the moon Charon was found to be orbiting Pluto

The average temperature on Pluto is estimated at -210ºC

In 2006, Pluto’s status as a planet was revoked, it is now considered a dwarf planet along with many other Kuiper belt objects

Assignment

Read Chapter 23, Section 3 (pg. 654-659) Do Section 23.3 Assessment #1-7 (pg. 659)