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Planets

Characteristics of Jupiter

Jupiter is the largest planet in the Solar System, one of the four giant planet, and one of the two giant gaseous planets. In composition it is similar to the Sun, with the dominant elements hydrogen and helium, but its mass is too small to drive nuclear fusion at its core, making it a planet rather than a star. Since the planet has no surface to speak of, the radius of the planet is defined as the point in the atmosphere where the pressure equals 1 bar (the pressure at sea level on Earth). There is also a difficulty in defining the rotation period of the planet. Two methods are used: the rotation period of Jupiter's magnetic field, and the rotation implied by the flattening of Jupiter at the poles.

Jupiter

In the table that follows, the observed values are taken from Yoder (1995).[1] Go to table of Jupiter's characteristics.

Characteristics of Jupiter

GM

1.26686(537±100)×1023 cm3 s−2

Mass

1.898×1030 g

Mean Radius

6.991(1±6)×109 cm

Equatorial Radius

7.149(2±4)×109 cm

Flattening

0.064(87±15)

Surface Gravity

2592 cm s−2

Escape Velocity

6.020×106 cm s−1

Average Density

1.326 g cm−3

Sidereal Rotation Period
(Magnetic)

9h 55m 27.3s

35727.3 s

Sidereal Rotation Period
(Hydrostatic)

9h 53m

35618±72 s

Obliquity to Orbit

3° 07

Sidereal Orbital Period

4330.595 d

Semimajor Axis

5.20336301 AU

Eccentricity

0.04839266

Solar Constant

5.05×104 ergs cm−2 s−1

Moons of Jupiter

Jupiter has four giant moons and dozens of tiny moons. The four giants are the Galilean moons. The table presented below contains only these four moons; all of the remaining moons around Jupiter have characteristic radii less than 100 km.

The distance column gives the distance of the moons from Jupiter's center in units of 108cm and in units of Jupiter's equatorial radius. The values in this table are taken from Norton's 2000.0.[2]

The Galilean Moons

Moon Distance Mass Radius
108cm Rj 1022g km

Io

421.6

5.90

8,869

1,815

Europa

670.9

9.38

4,780

1,569

Ganymede

1070.0

14.97

14,800

2,631

Calisto

1883.0

26.34

10,720

2400

[1] Yoder, Charles F. “Astrometric and Geodetic Properties of Earth and the Solar System.” In Global Earth Physics: A Handbook of Physical Constants edited by T.J. Ahrens, 1–31. AGU Reference Shelf, No. 1. Washington: American Geophysical Union, 1995.

[2] Norton, Arthur P. Nortons's 2000.0: Star Atlas and Reference Handbook. 18th ed. Edited by Ian Ridpath. Essex, England: Longman Scientific and Technical, 1989.

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