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== Orbital characteristics ==

== Orbital characteristics ==

Jupiter completes one slightly eccentric orbit around the [[Sun]] in 11.86 years, and returns to the same position in [[Earth]]'s night sky in roughly 399 years.<ref name=nasa2/><ref name=nelson/> Its mean distance from the Sun is about 5.2 AU--almost exactly the distance predicted by the [[Titius-Bode law]] of planetary distances. Though Jupiter is the fifth ''planet'' from the Sun, it is actually the ''sixth'' object of a size requiring the assumption of a spheroidal shape. Hence ''n=6'' is the proper number to use in the Bode's Law formula.

Jupiter completes one slightly eccentric orbit around the [[Sun]] in 11.86 years, and returns to the same position in [[Earth]]'s night sky in roughly 399 years.<ref name=nasa2/><ref name=nelson/> Its mean distance from the Sun is about 5.2 AU—almost exactly the distance predicted by the [[Titius-Bode law]] of planetary distances. Though Jupiter is the fifth ''planet'' from the Sun, it is actually the ''sixth'' object of a size requiring the assumption of a spheroidal shape. Hence ''n=6'' is the proper number to use in the Bode's Law formula.

== Rotational characteristics ==

== Rotational characteristics ==

== Physical characteristics ==

== Physical characteristics ==

Jupiter is about 318 times as massive as Earth, and has a radius of 71,492 km (44,423 miles). Its atmosphere is composed primarily of 86% [[hydrogen]], 14% [[helium]], and traces of [[methane]], [[ammonia]], [[phosphine]], [[water]], [[acetylene]], [[ethane]], [[germanium]], and [[carbon monoxide]].<ref name=nasa3/> It is so thick that no record exists of the surface, if Jupiter has one in the traditional sense--though Jupiter might have a heavy-metal core having a composition similar to that of [[Earth]] but 20 to 30 times as massive.<ref name=nasa3/>

Jupiter is about 318 times as massive as Earth, and has a radius of 71,492&nbsp;km (44,423 miles). Its atmosphere is composed primarily of 86% [[hydrogen]], 14% [[helium]], and traces of [[methane]], [[ammonia]], [[phosphine]], [[water]], [[acetylene]], [[ethane]], [[germanium]], and [[carbon monoxide]].<ref name=nasa3/> It is so thick that no record exists of the surface, if Jupiter has one in the traditional sense—though Jupiter might have a heavy-metal core having a composition similar to that of [[Earth]] but 20 to 30 times as massive.<ref name=nasa3/>

=== The Great Red Spot and other storms ===

=== The Great Red Spot and other storms ===

The planet endures continual storms. The most famous of these is the Great Red Spot, which has raged for at least three hundred years. The most precise estimate of its duration is 342 years,<ref name=Than>Than, Ker. "[http://www.space.com/scienceastronomy/060731_red_spots.html Differences Spotted in Jupiter's Big Red Storms]." <http://www.space.com/>, July 31, 2006. Accessed March 3, 2008.</ref> but this might refer merely to the first time that someone observed it with a telescope capable of resolving it. It is large enough to encompass the entirety of the [[Earth]] and rotates anticlockwise along Jupiter's equator. Winds at its edge circulate at 360 km/h<ref name=nasa3/>, far faster than those of the most powerful [[hurricane]] ever recorded on Earth.

The planet endures continual storms. The most famous of these is the Great Red Spot, which has raged for at least three hundred years. The most precise estimate of its duration is 342 years,<ref name=Than>Than, Ker. "[http://www.space.com/scienceastronomy/060731_red_spots.html Differences Spotted in Jupiter's Big Red Storms]." <http://www.space.com/>, July 31, 2006. Accessed March 3, 2008.</ref> but this might refer merely to the first time that someone observed it with a telescope capable of resolving it. It is large enough to encompass the entirety of the [[Earth]] and rotates anticlockwise along Jupiter's equator. Winds at its edge circulate at 360&nbsp;km/h,<ref name=nasa3/> far faster than those of the most powerful [[hurricane]] ever recorded on Earth.

=== Radiation of heat ===

=== Radiation of heat ===

==Shoemaker-Levy==

==Shoemaker-Levy==

In 1994, scientists were able to witness fragments of the comet Shoemaker-Levy 9 collide with Jupiter. These collisions laster for 6 days, starting on July 16th of that year, and was the first cosmic collision to be observed. During the impacts, at least 21 separate fragments with a size of up to 2 kilometers hit Jupiter, leaving scars in its atmosphere larger than several Earths.

In 1994, scientists were able to witness fragments of the comet Shoemaker-Levy 9 collide with Jupiter. These collisions laster for 6 days, starting on July 16 of that year, and was the first cosmic collision to be observed. During the impacts, at least 21 separate fragments with a size of up to 2 kilometers hit Jupiter, leaving scars in its atmosphere larger than several Earths.

== Problems for uniformitarian theories ==

== Problems for uniformitarian theories ==

[[Ulysses]] (February 1992) made a brief flyby of Jupiter in order to place itself in polar orbit around the Sun. Nevertheless [[European Space Agency]] scientists used this opportunity to make further measurements of Jupiter's magnetosphere and the effect upon it by the solar wind.

[[Ulysses]] (February 1992) made a brief flyby of Jupiter in order to place itself in polar orbit around the Sun. Nevertheless [[European Space Agency]] scientists used this opportunity to make further measurements of Jupiter's magnetosphere and the effect upon it by the solar wind.

[[Galileo Project|Galileo]] reached Jupiter in 1995. It released a probe to dive into Jupiter's atmosphere; that probe transmitted for nearly an hour before the tremendous pressures crushed it. Galileo's orbiter remained in the system for nearly eight years, through two extensions of its mission, and conducted the most extensive surveys of the Galilean moons to day. Eventually, with the craft low on fuel, mission planners dived it into Jupiter to prevent its possibly crashing into [[Europa]], rupturing Europa's ice sheet, and contaminating the liquid ocean that astronomers now suspect lies a mere 10 km deep to the ice and could yet harbor [[extraterrestrial life]].<ref name=nasa3/>

[[Galileo Project|Galileo]] reached Jupiter in 1995. It released a probe to dive into Jupiter's atmosphere; that probe transmitted for nearly an hour before the tremendous pressures crushed it. Galileo's orbiter remained in the system for nearly eight years, through two extensions of its mission, and conducted the most extensive surveys of the Galilean moons to day. Eventually, with the craft low on fuel, mission planners dived it into Jupiter to prevent its possibly crashing into [[Europa]], rupturing Europa's ice sheet, and contaminating the liquid ocean that astronomers now suspect lies a mere 10&nbsp;km deep to the ice and could yet harbor [[extraterrestrial life]].<ref name=nasa3/>

[[Cassini-Huygens Mission|Cassini]] flew by Jupiter briefly in 2000 on its way to [[Saturn]]. While in the Jovian system, it took the image shown at the top of this article.

[[Cassini-Huygens Mission|Cassini]] flew by Jupiter briefly in 2000 on its way to [[Saturn]]. While in the Jovian system, it took the image shown at the top of this article.