Jupiter

Jupiter Diameter: 142,984 km, 11 Earth diameters
Planetary Mass: 1.89x1027 kg, 317.8 Earth masses
Average Distance from Sun: 778 million km, 5.203 AU (astronomical units)
Length of Day: 9 hours 55 minutes
Length of Year: 11.86 Earth years
How many moons does Jupiter have?: 39
Planetary ring system: Yes
Average temperature: ~165 K (-108 C)
Atmospheric composition: Mostly Hydrogen and Helium.
AU stands for astronomical unit.
One AU is the average distance from the center of the Earth to the center of the Sun: 149,597,870 km
Facts about Jupiter's Moons
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Jupiter
Mass (1024 kg) 1,898.6
Volume (1010 km3) 143,128
Radius (1 bar level) (km)
 Equatorial 71,492
 Polar 66,854
Ellipticity 0.06487
Mean density (kg/m3) 1,326
Gravity (eq., 1 bar) (m/s2) 23.12
Escape velocity (km/s) 59.5
Number of natural satellites 39 Facts about Jupiter's Moons
Planetary ring system Yes
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Jupiter Orbital parameters
Semimajor axis (106 km) 778.57
Sidereal orbit period (days) 4,332.589
Perihelion (106 km) 740.52
Aphelion (106 km) 816.62
Synodic period (days) 398.88
Orbit inclination (deg) 1.304
Orbit eccentricity 0.0489
Sidereal rotation period (hours) 9.9250*
Length of day (hrs) 9.9259
Obliquity to orbit (deg) 3.13
Semimajor axis (106 km) Mean distance from the Sun (or other central body in the
 case of satellites) from center to center in 10^6 kilometers
Sidereal orbit period (days) The time it takes the body to make one revolution about
 the Sun relative to the fixed stars in days.
Synodic period (days) The time interval between similar configurations in the
 orbit (e.g. opposition) of the body and Earth, in days.
Perihelion (106 km) The point in a body's orbit closest to the
 Sun, in 10^6 kilometers.
Aphelion (106 km) The point in a body's orbit furthest from
 the Sun, in 10^6 kilometers.
Orbit inclination (deg) The inclination of the orbit to the ecliptic, in degrees.
 For satellites, this is with respect to the planet's
 equator.
Orbit eccentricity A measure of the circularity of the orbit, equal to
 (aphelion - perihelion distance)/(2 x semi-major axis)
 For a circular orbit, eccentricity = 0.
Sidereal rotation period (hrs) The time for one rotation of the body on its axis
 relative to the fixed stars, in hours. A minus sign
 indicates retrograde rotation.
Length of day (hrs) The average time in hours for the Sun to move from the
 noon position in the sky at a point on the equator back
 to the same position, on Earth this defines a 24 hour day.
Obliquity to orbit (deg) The tilt of the body's equator relative to the body's
 orbital plane, in degrees.
* System III (1965.0) coordinates 
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Jupiter Observational Parameters
Discoverer: Unknown
Discovery Date: Prehistoric
Distance from Earth
 Minimum (106 km) 588.5
 Maximum (106 km) 968.1
Apparent diameter from Earth
 Maximum (seconds of arc) 49.0
 Minimum (seconds of arc) 29.8
Mean values at opposition from Earth
 Distance from Earth (106 km) 628.76
 Apparent diameter (seconds of arc) 46.9
 Apparent visual magnitude -2.7
Maximum apparent visual magnitude -2.94
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Jovian Atmosphere
Surface Pressure: >>1000 bars
Temperature at 1 bar: ~165 K (-108 C)
Temperature at 0.1 bar: ~112 K (-161 C)
Density at 1 bar: ~0.16 kg/m3
Wind speeds
 Up to ~150 m/s (<30 degrees latitude)
 Up to ~40 m/s (>30 degrees latitude)
Atmospheric composition (by volume, uncertainty in parentheses)
 Major: Molecular hydrogen (H2) - 89.8% (2.0%); Helium (He) - 10.2% (2.0%)
 Minor (ppm): Methane (CH4) - 3000 (1000); Ammonia (NH3) - 260 (40);
 Hydrogen Deuteride (HD) - 28 (10); Ethane (C2H6) - 5.8 (1.5);
 Water (H2O) - ~4 (varies with pressure)
 Aerosols: Ammonia ice, water ice, ammonia hydrosulfide