Voyager 1 photo of Jupiter 
Voyager 2 close-up of Jupiter cloud features
Cassini mosaic image of Jupiter

Voyager 1 photo of Jupiter
(NASA/JPL)

Voyager 2 close-up of Jupiter
cloud features
(NASA/JPL)

Cassini spacecraft high resolution
mosaic image of Jupiter
(NASA/JPL)

King of the Gods

Our first stop in the Jovian system is a truly awesome sight. It is a gaseous planet of enormous proportions. This is the planet Jupiter. It is the fifth planet from the Sun and is the largest. It is also In fact, Jupiter is almost twice the size of all of the other planets combined. Over one thousand Earths could fit inside if it were hollow. Because of its gigantic size, Jupiter was named after the king of the gods in Roman mythology. In Greek mythology, he was known as Zeus, and was famous for hurling lightning bolts at earthbound mortals.

Jupiter is the fourth brightest object in the sky, so it has been known to exist since prehistoric times. It was Galileo who discovered Jupiter's four largest moons, Callisto, Europa, Ganymede, and Io, in 1610. We now know of 64 moons in orbit around Jupiter, ranging in size from just a few miles across to nearly Earth-sized. The Jovian system is like a miniature solar system within a solar system. With so many satellites tugging on Jupiter with their tidal forces, these moons are actually causing Jupiter's rotation to slow down. These same tidal forces are also pushing the moons farther away from the massive planet.

Voyager 2 closeup of Jupiter's famous red spot
Galileo image of Jipiter's moon Io
Voyager 1 close-up of Jupiter's cloud details

Voyager 2 closeup of Jupiter's famous red spot (NASA/JPL)

Galileo image of Jipiter's moon Io
(NASA/JPL/University of Arizona)

Galileo image of Jipiter's moon Io
(NASA/JPL/University of Arizona)

The Famous Red Spot

Perhaps the most famous feature of Jupiter is its giant red spot. This spot is actually a gigantic storm system. This large blemish is a high-pressure region where the winds blow in a counter-clockwise direction at over 250 miles (402 km) per hour. The cloud tops are much higher and colder than the surrounding clouds. This accounts for the spot's darker color. With a diameter of more than 16,000 miles (25,000 km), this storm is twice the size of the Earth!  Many spots and colorful bands appear and disappear in Jupiter's turbulent atmosphere, but the great red spot has been know to exist for more than 300 years. Astronomers do not yet know what forces have kept this storm together for so long. And nobody knows just how much longer it will last.

Spots of a different kind were seen in 1994 when a comet named Shoemaker-Levy 9 smashed into the planet. The comet had broken into 21 separate fragments as a result of a close encounter with Jupiter's massive gravitational forces. On July 16 1994, for seven days, these fragments bombarded the giant planet. The impacts left monstrous black scars on the Jupiter's surface. Explosive plumes several times the size of Earth were observed, and the dark scars remained visible on the planet for nearly a year. It was one of the most watched astronomical events in history, and it proved once and for all that comets do hit planets.

Voyager 2 mosaic image of Jupiter's cloud bands showing details

Mosaic image created by the Cassini spacecraft showing details of Jupiter's cloud bands.
The great red spot can be seen in addition to several other storms visible as smaller round spots.(NASA/JPL)

Features of Jupiter

Jupiter has amazed and intrigued astronomers for centuries. It has been visited by a total of six spacecraft, including the current Galileo mission. In 1995, Galileo dropped a probe into Jupiter's atmosphere. The probe took measurements and gave us our first clues as to what was inside Jupiter's thick atmosphere. With this data, and data collected on previous missions, we now know that Jupiter is essentially a gigantic ball of gas. The planet is composed mainly of hydrogen, with helium and traces amounts of other gases. One surprising find was that there is much less water in Jupiter's atmosphere than previously expected. Astronomers believe that Jupiter has no solid surface. Instead the gases get thicker and denser as they get closer to the planet's center. The extreme pressure at Jupiter's core compresses the hydrogen into a rare liquid metallic state. The planet may also have a small, rocky core about 10 times the size of Earth.

Jupiter's outer atmosphere is extremely dynamic. Colorful bands and spots can be see rotating and changing regularly. The colors in the bands are believed to be the result of chemical reactions in the atmosphere. The Galileo probe measured wind speeds exceeding 400 miles (643 km) per hour.

A big surprise revealed by the Voyager 1 spacecraft was that Jupiter has rings, much like Saturn. But unlike Saturn's rings, Jupiter's rings are very delicate and simple. These rings are divided into three main segments, and were not known to exist prior to Voyager's discovery because they are too thin to be seen from Earth.

One other item in Jupiter's long list of oddities is its magnetic field. It is so strong that is actually extends past the orbit of Saturn. In fact, it is 4000 times stronger than Earth's magnetic field. Even stranger still is the fact that Jupiter's rotation is so fast - only 9.8 Earth hours - that the planet actually bulges out in the center. A close examination of any Jupiter photo will reveal that the planet is more oval shaped than round.

 

 

Statistics for Jupiter

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

......

......

......

......

......

......

......

......

......

......

......

......

......

88,823 miles (142,984 km)

64

482,546,000 miles (778,330,000 km)

9.84 hours

4333 days

0.0483

1.308 degrees

3.12 degrees

-185° F (-121° C)

Hydrogen

0.7 bars

100 miles (161 km)

-2.7

 

The Moons of Jupiter

Name

Pronunciation

Order

Diameter
(km) 

Orbital Period
(days)

Distance
(km)

Year
Discovered

Metis

Adrastea

Amalthea

Thebe

Io

Europa

Ganymede

Callisto

Themisto

Leda

Himalia

Lysithea

Elara

S/2000 J11

Carpo

S/2003 J12

Euporie

S/2003 J3

S/2003 J18

Thelxinoe

Euanthe

Helike

Orthosie

Iocaste

S/2003 J16

Praxidike

Harpalyke

Mneme

Hermippe

Thyone

Ananke

Herse

Aitne

Kale

Taygete

S/2003 J19

Chaldene

S/2003 J15

S/2003 J10

S/2003 J23

Erinome

Aoede

Kallichore

Kalyke

Carme

Callirrhoe

Eurydome

Pasithee

S/2010 J1

Kore

Cyllene

Eukelade

S/2003 J4

Pasiphae

Hegemone

Arche

Isonoe

S/2003 J9

S/2003 J5

Sinope

Sponde

Autonoe

Megaclite

S/2003 J2

MEE-tis

a-DRAS-tee-uh

am-al-THEE-uh

THEE-bee

EYE-oh

yur-ROH-pah

GAN-ee-meed

kah-LISS-toe

them-ISS-toe

LEE-duh

him-MAH-lee-uh

ly-SITH-ee-uh

ee-LAH-ruh

-

KAR-poh

-

yoo-POR-ee

-

-

thelk-SIN-o-ee

yoo-AN-thee

or-THO-see-uh

or-THOH-see

EYE-o-KAS-tee

-

prak-SID-uh-kee

har-PAL-uh-kee

NEE-mee

her-MIP-ee

thye-OH-nee

a-NANG-kee

HUR-see

et-NEE

KAY-lee

tay-IJ-uh-tee

-

kal-DEE-nee

-

-

-

err-RIN-o-mee

ay-EE-dee

kuh-LIK-o-ree

KAL-uh-kee

KAR-mee

ka-LIRR-oh-ee

yoo-RID-uh-mee

pah-SITH-uh-thee

-

KOHR-ee

suh-LEE-nee

ew-KEL-uh-dee

-

pah-SIF-uh-ee

huh-JEM-uh-nee

ARK-ee

eye-SON-oh-ee

-

-

sy-NOH-pee

SPON-dee

aw-TON-o-ee

meg-uh-KLY-tee

-

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

63

64

60×40×34

20×16×14

250×146×128

116×98×84

3,643

3,122

5,262

4,821

8

16

170

36

86

4

3

1

2

2

2

2

3

4

2

5

2

7

4

2

4

4

28

2

3

2

5

2

4

2

2

2

3

4

2

5

46

9

3

2

2

2

2

4

2

60

3

3

4

1

4

38

2

4

5

2

7h 4m 29s

7h 9m 30s

11h 57m 23s

16h 11m 17s

1.769

3.551

7.154

16.689

129.87

241.75

250.37

259.89

261.14

287.93

458.62

−482.69

−538.78

−561.52

−569.73

−597.61

−598.09

−601.40

−602.62

−609.43

−610.36

−613.90

−624.54

−627.48

−629.81

−639.80

−642.02

−672.75

−679.64

−685.32

−686.67

−699.12

−699.33

−699.68

−700.13

−700.54

−711.96

−714.66

−717.81

−721.02

−721.82

−722.62

−723.36

−726.93

-723.20

−776.02

−731.10

−735.20

−739.29

−741.09

−745.50

−746.19

−750.13

−752.84

−758.34

−762.33

−771.60

−772.17

−792.44

−1,077.02

127,690

128,690

181,366

221,889

421,700

671,034

1,070,412

1,882,709

7,393,216

11,187,781

11,451,971

11,740,560

11,778,034

12 570 424

17,144,873

17,739,539

19,088,434

19,621,780

19,812,577

20,453,753

20,464,854

20,540,266

20,567,971

20,722,566

20,743,779

20,823,948

21,063,814

21,129,786

21,182,086

21,405,570

21,454,952

22,134,306

22,285,161

22,409,207

22,438,648

22,709,061

22,713,444

22,720,999

22,730,813

22,739,654

22,986,266

23,044,175

23,111,823

23,180,773

23,197,992

23,214,986

23,230,858

23,307,318

23,314,335

23,345,093

23,396,269

23,483,694

23,570,790

23,609,042

23,702,511

23,717,051

23,800,647

23,857,808

23,973,926

24,057,865

24,252,627

24,264,445

24,687,239

30,290,846

1979

1979

1892

1979

1610

1610

1610

1610

1975/2000

1974

1904

1938

1905

2001

2003

2003

2002

2003

2003

2003

2002

2003

2002

2001

2003

2001

2001

2003

2002

2002

1951

2003

2002

2002

2001

2003

2001

2003

2003

2004

2001

2003

2003

2001

1938

2000

2002

2002

2010

2003

2003

2003

2003

1908

2003

2002

2001

2003

2003

1914

2002

2002

2001

2003

 

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