Hubble high resolution photo of Saturn
Cassini close-up image of Saturn and its rings
Cassini image showing planet's shadow on the rings

Hubble high-resolution photo of the planet Saturn
(NASA/JPL)

Cassini close-up image of Saturn and its many rings
(NASA/JPL/Space Science Institute)

Cassini image showing Saturn's shadow falling across the rings
(NASA/JPL/Space Science Institute)

God of the Harvest

As we first enter the Saturnian system, we are presented with a sight of sheer beauty. It is a giant gas planet with a delicate system of silky rings. This is the planet Saturn. It is the sixth planet from the Sun and is the second largest in the Solar System. Saturn was named after the Roman god of agriculture and the harvest. His Greek counterpart was Chronus, the youngest of the Titans.

Many consider Saturn to be the most beautiful object in the Solar System. It is one of the brightest objects in the night sky, and has been known since prehistoric times. Galileo was the first person to observe Saturn through a telescope in 1610. He noticed the planet's odd shape, but was unable to figure out the significance of what he had seen. In 1659, Christiaan Huygens was able to correctly identify the odd shape as Saturn's rings. Since then, Saturn has been visited by three Spacecraft including Pioneer 11, Voyagers 1 and 2, and Cassini. The Cassini probe arrived at Saturn in 2004 and gave us spectacular new views of the planet and its moons. Saturn is surrounded by a small army of 60 known moons second only to Jupiter in number. Most of these moons are small, but seven of them are large enough to warrant further investigation.

Cassini false color image of Saturn cloud formations
Cassini image of the moon Dione orbiting above Saturn's rings
False color Cassini image of Saturn clouds and details

Cassini false color image of Saturn cloud formations
(NASA/JPL/Space Science Institute)

Cassini image of the moon Dione orbiting above Saturn's rings
(NASA/JPL/Space Science Institute)

False color Cassini image of Saturn clouds and details
(NASA/JPL/Space Science Institute)

The Ringed Planet

Without a doubt the most striking feature of Saturn is its rings. Unlike the rings of Jupiter, which were not discovered until the Voyager 1 encounter in 1979, Saturn's rings have been known to exist since 1659. This is due to the fact that the ring system is quite large and bright. It can easily be seen from Earth with a small telescope. The view of Saturn's rings from Earth actually changes from year to year. This phenomenon occurrs because the tilt of Saturn's rings changes as it orbits the Sun. Because the rings are less than a mile in thickness, they seem to disappear completely every few years when they appear on edge as seen from Earth. This change in the ring system's orientation causes the brightness, or apparent magnitude of the planet to change as well.

Saturn has three main ring bands. They are identified as the A, B, and C-rings. A large gap can be seen between the A and B rings. This is known as the Cassini division, and was named after Giovanni Cassini, the discoverer the gap as well as four of Saturn's largest moons. It wasn't until the Voyager encounters with Saturn in 1980 and 1981 that the true mystery of Saturn's rings was unveiled. The ring system is really composed of seven rings with extremely complex structures. The larger rings are actually composed of many smaller ringlets. The Voyager probes also found strange radial, spoke-like structures in the rings. These are believed to be caused by dust particles. Saturn's innermost ring, the F-ring, appears to be knotted or braided. Astronomers are not sure yet what causes this strange phenomenon.

The Voyager probes revealed the existence of small moons in and near the rings. They are called "shepherding satellites" because they are believed to help keep the rings in place. Without the gravitation of these moons, the ring particles might fly off into space and the rings would be lost.

The origin of Saturn's rings is not well understood. They appear to be composed of millions of tiny particles of ice and rock, each in its own orbit around the planet. The size of these particles ranges from as small as a dust grain to as large as an iceberg. Astronomers believe that the rings could be the debris of one or more moons that were pulverized by asteroid or comet impacts.

This Cassini mosaic image shows that Saturn's stunning system of rings is much more complex than originally thought

This Cassini mosaic image shows that Saturn's stunning system of rings is much more complex than originally thought. They are composed of hundreds of smaller rings and gaps like the groves on a phonograph record.
(NASA/JPL/Space Science Institute)

Features of Saturn

Even though the ring system is Saturn's most striking feature, the planet is also interesting in a number of other ways. Saturn is a gas giant with a chemical composition very similar to that of Jupiter. It is composed of about 75% hydrogen and 25% helium, with traces of methane, water, and ammonia. Astronomers believe that Saturn's interior is also similar to that of Jupiter, with a core of rock and ice, surrounded by a layer of liquid metallic hydrogen. There is no solid surface on Saturn. Instead, the atmospheric gases get denser and thicker as they approach the planet's center. Saturn is also the least dense of all the planets. Its specific gravity is only 0.7, which is less than that of water. If Saturn could be placed into a giant container of water, it would actually float!

Saturn shares many other features with its close cousin, Jupiter, such as high winds and cloud banding. Winds at the equator can reach an unbelievable 1,100 miles per hour. The horizontal bands on Saturn are much fainter than those on Jupiter. The Hubble space telescope has also revealed that storms occasionally erupt in Saturn's turbulent atmosphere. Like most of the other gas giant planets, Saturn has a strong magnetic field. Like Jupiter, Saturn is visibly flattened at its poles. This is caused by the planet's rapid rotation of only 10 hours, 39 minutes. In July of 2004, the Cassini probe is scheduled to arrive at Saturn. It will orbit the planet and send back detailed images and data. It will also drop the Huygens probe into the atmosphere of Saturn's moon Titan. There it will land and sample the composition of Titan's thick atmosphere and send back images of the surface.

 

 

Statistics for Saturn

Diameter

Known Natural Satellites

Mean Distance from the Sun

Rotational Period

Orbital Period

Orbital Eccentricity

Orbital Inclination

Inclination of Axis

Mean Cloud Temperature

Main Atmospheric Component

Atmospheric Pressure

Atmospheric Depth

Apparent Magnitude

......

......

......

......

......

......

......

......

......

......

......

......

......

74,565 miles (120,536 km)

62

884,740,000 miles (1,429,400,000 km)

10.25 days

29.46 years

0.056

2.488 degrees

26.73 degrees

-193° F (-125° C)

Hydrogen

1.4 bars

90 miles (145 km)

0.67

 

The Moons of Saturn

Name

Pronunciation

Order

Diameter
(km) 

Orbital Period
(days)

Distance
(km)

Year
Discovered

S/2009 S 1

Pan

Daphnis

Atlas

Prometheus

Pandora

Epimetheus

Janus

Aegaeon

Mimas

Methone

Anthe

Pallene

Enceladus

Tethys

Telesto

Calypso

Dione

Helene

Polydeuces

Rhea

Titan

Hyperion

Iapetus

Kiviuq

Ijiraq

Phoebe

Paaliaq

Skathi

Albiorix

S/2007 S 2

Bebhionn

Erriapus

Skoll

Siarnaq

Tarqeq

S/2004 S 13

Greip

Hyrrokkin

Jarnsaxa

Tarvos

Mundilfari

S/2006 S 1

S/2004 S 17

Bergelmir

Narvi

Suttungr

Hati

S/2004 S 12

Farbauti

Thrymr

Aegir

S/2007 S 3

Bestla

S/2004 S 7

S/2006 S 3

Fenrir

Surtur

Kari

Ymir

Loge

Fornjot

-

PAN

DAF-nis

AT-lus

pra-MEE-thee-us

pan-DOR-uh

ep-eh-MEE-thee-us

JAY-nus

ee-JEH-un

MY-mas

mi-THOH-nee

AN-thee

puh-LEE-nee

en-SEL-uh-dus

TETH-iss

tah-LESS-toh

ka-LIP-soh

dy-OH-nee

HEL-en-ee

POL-i-DEW-seez

REE-uh

TY-tun

hy-PEER-ee-un

eye-AP-uh-tus

KEE-vee-ookh

EE-ye-rahkh

FEE-bee

PAH-lee-ahkh

SKAH-thee

AL-bee-OR-iks

-

BEV-een

AIR-ee-AH-po

SKOL

SEE-ar-nahkh

TAR-kayk

-

GRAYP

hirr-ROK-in

yarn-SAKS-uh

TAR-vos

MOON-dil-FAIR-ee

-

-

berr-YEL-mirr

NAR-vee

SOOT-oong-er

HAH-tee

-

far-BOW-tee

THRIM-er

EYE-irr

-

BEST-luh

-

-

FEN-rirr

SURR-ter

KAR-ee

IM-ir

LOH-gee

FOR-nyot

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

0.3

28

7.8

30

86

81

113

179

0.5

397

3.2

2

4.4

504

1,066

25

21

1,123

33

2.6

1,529

5,151

266

1,472

16

12

214

22

8

32

6

6

10

6

40

7

6

6

8

6

15

7

6

4

6

7

7

6

5

5

7

6

5

7

6

6

4

6

7

18

6

6

0.47

0.58

0.59

0.6

0.61

0.63

0.69

0.69

0.81

0.94

1.01

1.04

1.15

1.37

1.89

1.89

1.89

2.74

2.74

2.74

4.52

15.95

21.28

79.32

448.16

451.77

−545.09

692.98

−732.52

774.58

−792.96

838.77

844.89

−862.37

884.88

894.86

−905.85

−906.56

−914.29

−943.78

944.23

−956.70

−972.41

−985.45

−985.83

−1,008.45

−1,022.82

−1,033.05

−1,048.54

−1,054.78

−1,078.09

−1,094.46

−1,100.0

−1,101.45

−1,101.99

−1,142.37

−1,212.53

−1,242.36

−1,245.06

−1,254.15

−1,300.95

−1,432.16

117,000

133,584

136,505

137,670

139,380

141,720

151,422

151,472

167,500

185,404

194,440

197,700

212,280

237,950

294,619

294,619

294,619

377,396

377,396

377,396

527,108

1,221,930

1,481,010

3,560,820

11,294,800

11,355,316

12,869,700

15,103,400

15,672,500

16,266,700

16,560,000

17,153,520

17,236,900

17,473,800

17,776,600

17,910,600

18,056,300

18,065,700

18,168,300

18,556,900

18,562,800

18,725,800

18,930,200

19,099,200

19,104,000

19,395,200

19,579,000

19,709,300

19,905,900

19,984,800

20,278,100

20,482,900

20,518,500

20,570,000

20,576,700

21,076,300

21,930,644

22,288,916

22,321,200

22,429,673

22,984,322

24,504,879


2009

1990

2005

1980

1980

1980

1977

1966

2008

1789

2004

2007

2004

1789

1684

1980

1980

1684

1980

2004

1672

1655

1848

1671

2000

2000

1899

2000

2000

2000

2007

2004

2000

2006

2000

2007

2004

2006

2006

2006

2000

2000

2006

2004

2004

2003

2000

2004

2004

2004

2000

2004

2007

2004

2004

2006

2004

2006

2006

2000

2006

2004

 

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