Astronomy Ch. 14 Saturn

Saturn has the same composition as

Jupiter and the Sun

Saturn is named after

The Roman God of wealth and agriculture and father of Jupiter

Saturns atmosphere is rich in

H and He

Saturn rotates as fast as , but is __ as oblate

Fast, twice

Saturn’s Interior

• Radiates 1.8 times as much energy as it receives from the Sun

• Falling objects of He release energy as they pick up speed, thus heating the planet

• Similar composition as Jupiter, but in less proportions

Saturn’s Magnetic Field

• Weaker magnetic field and radiation belts than Jupiter

• Magnetic field is 20 times less intense that Jupiters

• Produces strong Auroras

• Uncommon in the Solar System: its magnetic axis (M) aligns with its rotation axis

Saturn’s Auroras

• Auroras on Saturn occur in rings around the planet’s magnetic poles and change day by day

• Because the magnetic field is not inclined very much to the axis of rotation, the auroral rings occur nearly at the planet’s geometrical poles

Saturn’s Atmosphere

• Three-layered cloud structure, just like Jupiter

• Belt-zone no has distinct as Jupiter

• Fewer winds to create boundaries, but winds much stronger than Jupiters (5x faster)

• Eastward wind at the equator of Saturn blows 500 m/s (1000 mph)

• Saturns belt zone circulation is not very distinct at visible wavelength

• Saturn is colder than Jupiter, the clouds form deeper in the hazy atmosphere

Saturns Moons and Rings

• More than 60 moons with charted orbits

• Most or icy and small

• Rings are numerous; made of icy particles

• The rings are controlled by many different natural processes

Saturn’s Moons: Titan

• Saturn’s largest moon, about the size of Ganymede

• Rocky core, but also large amount of ice

• Has an atmosphere at thick as Earth, containing 98% Nitrogen (N) and 2% Methane (CH4) and Ethane (C2H6)

• Surface is cold: 94K

• Rains methane

Saturn’s smaller moons

• Enceladus

• Dione

• Iapetus

• Phoebe

• Mimas

• Tethys

• Rhea

• Hyperion

Phoebe and Tethys

• Phoebe and Tethys have ancient cratered surfaces, but they differ in interesting ways

• Phoebe is only 1/5 the diameter of Tethys and shows no sign of internal heat to indicate surface activity

• Tethys has smooth areas and long cracks on its surface, showing that it has been active

Enceladus

• Potential of liquid water beneath its icy surface

• The icy surface of Enceladus does not look old, although some areas have few craters, and lanes of grooved terrain

• Resemble the surface of Jupiters moon Ganymede

• Enceladus is venting water, ice, and organic molecules from geysers near its south pole

Iapetus

• Leading side accumulated a coating of dark material

• The poles and trailing side of the moon have much cleaner ice

Roche Limit of a celestial body depends on its

Mass and density of the attracted objects

From earth, astronomers can see how many rings on saturn?

3 rings labeled A,B, and C

What missions revealed over a thousand ringlets within Saturn’s rings?

Voyager and Cassini

Saturn’s Rings

• Made up of billions of ice particles, each in its own orbit around the planet

• No leftover particles from Saturn’s formation, must be continually replenished

• Shepherd satellites confine rings in narrow strands or keep edges sharp

• Rings are created from and controlled by the planets moons.

• Without the moons there would be no rings

History of Saturn

Parallels that of Jupiter

• Formed from cold gas in outer solar nebula, where ices could condense

• Grew rapidly and became massive enough to capture H and He gas

• Rapid rotation and outward flow of heat drives dynamo effect for a strong magnetic field

• Planetary rings are not primordial and not stable for 4.6 billion years- perhaps results of a catastrophic event