Jupiter (astronomy)

Jupiter

Full-disc view of Jupiter in natural color in April 2014
Designations
Pronunciation	/ˈdʒuːpɪtər/ ( listen)
Adjectives
Orbital characteristics
Epoch J2000
Aphelion	816.62 million km (5.4588 AU)
Perihelion	740.52 million km (4.9501 AU)
Semi-major axis	778.57 million km (5.2044 AU)
Eccentricity	6998489000000000000♠0.0489
Orbital period	7001118620000000000♠11.862 yr 7008374335776000000♠4,332.59 d 7004104758000000000♠10,475.8 Jovian solar days
Synodic period	7007344632320000000♠398.88 d
Average orbital speed	13.07 km/s (8.12 mi/s)
Mean anomaly	20.020°
Inclination	1.303° to ecliptic 6.09° to Sun's equator 0.32° to invariable plane
Longitude of ascending node	100.464°
Argument of perihelion	273.867°
Known satellites	69 (as of 2017[update])
Physical characteristics
Mean radius	69,911 km (43,441 mi)
Equatorial radius	71,492 km (44,423 mi) 7001112090000000000♠11.209 Earths
Polar radius	66,854 km (41,541 mi) 7001105170000000000♠10.517 Earths
Flattening	6998648700000000000♠0.06487
Surface area	6.1419×1010 km2 (2.3714×1010 sq mi) 7002121900000000000♠121.9 Earths
Volume	1.4313×1015 km3 (3.434×1014 cu mi) 7003132100000000000♠1,321 Earths
Mass	1.8982×1027 kg (4.1848×1027 lb) 7002317800000000000♠317.8 Earths 1/1047 Sun
Mean density	1,326 kg/m3 (2,235 lb/cu yd)
Surface gravity	24.79 m/s2 (81.3 ft/s2) 2.528 g
Moment of inertia factor	6999254000000000000♠0.254 I/MR2 (estimate)
Escape velocity	59.5 km/s (37.0 mi/s)
Sidereal rotation period	9.925 hours (9 h 55 m 30 s)
Equatorial rotation velocity	12.6 km/s (7.8 mi/s; 45,000 km/h)
Axial tilt	3.13° (to orbit)
North pole right ascension	268.057°; 17h 52m 14s
North pole declination	64.495°
Albedo	0.343 (Bond) 0.538 (geometric)
Surface temp. min mean max 1 bar level 165 K (−108 °C) 0.1 bar 112 K (−161 °C)
Apparent magnitude	2999840000000000000♠−1.6 to 2999706000000000000♠−2.94
Angular diameter	29.8″ to 50.1″
Atmosphere
Surface pressure	20–200 kPa; 70 kPa
Scale height	27 km (17 mi)
Composition by volume	by volume: 89.8±2.0% hydrogen (H2) 10.2±2.0% helium (He) 0.3±0.1% methane (CH4) 0.026±0.004% ammonia (NH3) 0.0028±0.001% hydrogen deuteride (HD) 0.0006±0.0002% ethane (C2H6) 0.0004±0.0004% water (H2O) Ices: ammonia (NH3) water (H2O) ammonium hydrosulfide (NH4SH)

by volume:

Ices:

Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a giant planet with a mass one-thousandth that of the Sun, but two and a half times that of all the other planets in the Solar System combined. Jupiter and Saturn are gas giants; the other two giant planets, Uranus and Neptune are ice giants. Jupiter has been known to astronomers since antiquity. The Romans named it after their god Jupiter. When viewed from Earth, Jupiter can reach an apparent magnitude of −2.94, bright enough for its reflected light to cast shadows, and making it on average the third-brightest object in the night sky after the Moon and Venus.

Jupiter is primarily composed of hydrogen with a quarter of its mass being helium, though helium comprises only about a tenth of the number of molecules. It may also have a rocky core of heavier elements, but like the other giant planets, Jupiter lacks a well-defined solid surface. Because of its rapid rotation, the planet's shape is that of an oblate spheroid (it has a slight but noticeable bulge around the equator). The outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence and storms along their interacting boundaries. A prominent result is the Great Red Spot, a giant storm that is known to have existed since at least the 17th century when it was first seen by telescope. Surrounding Jupiter is a faint planetary ring system and a powerful magnetosphere. Jupiter has at least 69 moons, including the four large Galilean moons discovered by Galileo Galilei in 1610. Ganymede, the largest of these, has a diameter greater than that of the planet Mercury.