Jupiter (planet)

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In astronomy, Jupiter is the largest planet in the solar system. It is named after the Ancient Roman god, the king of the gods and god of the sky. It's large mass probably disrupted a forming planet to produce the asteroid belt. 

It also acts to gravitationally absorb many passing asteroids and comets, partly protecting the inner solar system from too many large asteroids impacting other planets.

Image of Jupiter from the Cassini spacecraft passing by on it's way to Saturn. image: JPL/NASA

Orbit basics:

• Distance from sun: between 740,679,835 and 816,001,807 km
• Orbital period (it's year):  11.862615 Earth years
• Moons (Natural Satellites): 
• 67 with 51 less than 10 km in diameter.
• 4 largest moons called Galilean moons: Io, Europa, Ganymede, Callisto
• Faint rings (means you need to use a very strong telescope or spacecraft to see them)

Planet basics:

• Type of planet: Gaseous giant
• Length of day: 9.92496 hours
• Average radius: 69,911 km
• Mass: 1.8981 x 10²⁷ kg or 317.828 x Earth
• Gravity near cloud tops: 24.79 m/s² or 2.527 g
• Temperature of cloud tops: -148 °C
• Atmosphere: Thickness varies with depth to core, extreme wind speeds (300- to 400 m/s at the equator about 1,440 km/h) and planetary scale cyclonic storms.
• Pressure: varies according to depth to core.
• Atmospheric composition: 
• Hydrogen
• Helium
• Traces of Ammonia, Hydrogen sulphides, methane

References:

•  NASA Solar System Exploration: Planets: Jupiter Facts & Figures
• Composition of Jupiters Atmosphere ScienceDirect
• Dynamics of Jupiter’s Atmosphere, Arizona Univeristy (pdf)
• see also Solar System Dynamics at JPL for accurate details of orbital elements (set Ephemeris Type option to ELEMENTS and select sun, change table settings units to km)
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