Jupiter

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This article is about the planet. For other uses, see Jupiter (disambiguation).

Jupiter  

A composite Cassini image of Jupiter. The dark spot is the shadow of Europa.
Designations
Pronunciation	i /ˈdʒuːpɪtər/[1]
Adjective	Jovian
Orbital characteristics[2][3]
Epoch J2000
Aphelion	816,520,800 km (5.458104 AU)
Perihelion	740,573,600 km (4.950429 AU)
Semi-major axis	778,547,200 km (5.204267 AU)
Eccentricity	0.048775
Orbital period	4,331.572 days 11.85920 yr 10,475.8 Jupiter solar days[4]
Synodic period	398.88 days[5]
Average orbital speed	13.07 km/s[5]
Mean anomaly	18.818°
Inclination	1.305° to Ecliptic 6.09° to Sun's equator 0.32° to Invariable plane[6]
Longitude of ascending node	100.492°
Argument of perihelion	275.066°
Satellites	63
Physical characteristics
Equatorial radius	71,492 ± 4 km[7][8] 11.209 Earths
Polar radius	66,854 ± 10 km[7][8] 10.517 Earths
Flattening	0.06487 ± 0.00015
Surface area	6.21796×1010 km²[8][9] 121.9 Earths
Volume	1.43128×1015 km³[5][8] 1321.3 Earths
Mass	1.8986×1027 kg[5] 317.8 Earths 1/1047 Sun[10]
Mean density	1.326 g/cm³[5][8]
Equatorial surface gravity	24.79 m/s²[5][8] 2.528 g
Escape velocity	59.5 km/s[5][8]
Sidereal rotation period	9.925 h[11]
Equatorial rotation velocity	12.6 km/s 45,300 km/h
Axial tilt	3.13°[5]
North pole right ascension	268.057° 17 h 52 min 14 s[7]
North pole declination	64.496°[7]
Albedo	0.343 (bond) 0.52 (geom.)[5]
Surface temp.    1 bar level    0.1 bar	min mean max 165 K[5] 112 K[5]
Apparent magnitude	-1.6 to -2.94[5]
Angular diameter	29.8" — 50.1"[5]
Atmosphere[5]
Surface pressure	20–200 kPa[12] (cloud layer)
Scale height	27 km
Composition	89.8±2.0% Hydrogen (H2) 10.2±2.0% Helium ~0.3% Methane ~0.026% Ammonia ~0.003% Hydrogen deuteride (HD) 0.0006% Ethane 0.0004% water Ices: Ammonia water ammonium hydrosulfide(NH4SH)

Jupiter is the fifth planet from the Sun and the largest planet within the Solar System.^[13] It is a gas giant with a mass slightly less than one-thousandth of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn, Uranus and Neptune. Together, these four planets are sometimes referred to as the Jovian planets.
The planet was known by astronomers of ancient times and was associated with the mythology and religious beliefs of many cultures. The Romans named the planet after the Roman god Jupiter.^[14] When viewed from Earth, Jupiter can reach an apparent magnitude of −2.94, making it on average the third-brightest object in the night sky after the Moon and Venus. (Mars can briefly match Jupiter's brightness at certain points in its orbit.)
Jupiter is primarily composed of hydrogen with a quarter of its mass being helium; it may also have a rocky core of heavier elements. Because of its rapid rotation, Jupiter's shape is that of an oblate spheroid (it possesses 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 the planet is a faint planetary ring system and a powerful magnetosphere. There are also at least 63 moons, including the four large moons called the Galilean moons that were first discovered by Galileo Galilei in 1610. Ganymede, the largest of these moons, has a diameter greater than that of the planet Mercury.
Jupiter has been explored on several occasions by robotic spacecraft, most notably during the early Pioneer and Voyager flyby missions and later by the Galileo orbiter. The most recent probe to visit Jupiter was the Pluto-bound New Horizons spacecraft in late February 2007. The probe used the gravity from Jupiter to increase its speed. Future targets for exploration in the Jovian system include the possible ice-covered liquid ocean on the moon Europa.