Jupiter

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Jupiter

Jupiter is the fifth planet in the Solar System, counted from the Sun, and the largest planet in it. It is named after the chief Roman god (or Zeus as he was known to the Greeks). It is categorized as a "gas giant." This is a reference to the low density of the planet, not to its manners.


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[edit] Great Red Spot

One of Jupiter's more fascinating features is the Great Red Spot, a huge weather system in its atmosphere that resembles a terrestrial cyclone, except for its relatively consistent appearance and its persistence (it has been observed for more than a century).

[edit] Comet impact

In 1994 (was it really that long ago?) the comet Shoemaker-Levy 9, after breaking into fragments, collided with Jupiter. This was the first observed example of extraterrestrial objects colliding. The resultant "dark spots" in the Jovian atmosphere ranged up to 12 000 km (approximately equal to the diameter of the earth), but dissipated in under a day.

[edit] Jupiter ignition

"Jupiter ignition" refers to the notion that Jupiter can be turned into star, popular in some crank/conspiracy theorist circles. It probably originates with the fact that Jupiter and other gas giants are sometimes called "failed stars" in popular science. It was a plot point in Arthur Clarke's 2010: Odyssey Two, where the second Monolith starts multiplying and "ignites" Jupiter by increasing its density. The main problem is that Jupiter simply doesn't have enough mass to sustain a star-like nuclear fusion reaction. There are objects that stand on the boundary between gas giants and stars - brown dwarfs - but the lower boundary of their mass is about 13 times the mass of Jupiter, and, despite the fact that some of them can fuse deuterium or lithium, they are still "cool" relative to stars on the main sequence.

The idea has different permutations and is usually dusted off every time some major event happens on Jupiter. One possible originator of the conspiracy twist is Richard Hoagland, who said back in 2003 that NASA crashing the Galileo spacecraft into the planet would "ignite" it into a star. His "theory" being that the tiny amount of plutonium-238, that is used to power the craft through radioactive decay, would be crushed in the exceptionally high pressure of the atmosphere. This would cause an atomic explosion which, like a hydrogen bomb, would cause the surrounding material to undergo nuclear fusion and turn Jupiter into a new star.[1] Because to him all stars need is hydrogen and fire to be stars, mass doesn't matter, nor does the difference between the deuterium/tritium mix used in a hydrogen bomb and the light hydrogen inside Jupiter. He has never explained why anyone would want to do that, since we would all die from radiation or the Earth would be torn apart by tidal forces.[2]

[edit] Moons and rings

Jupiter has dozens of moons as well as a faint ring system. Its most famous moons are those discovered by Galileo—another reason why he got in trouble with the Church, as that conflicted with geocentrism.

The largest, Ganymede is the largest moon in the Solar System, having more volume than the planet Mercury, though less mass and therefore less density. Before light and air pollution became an issue, Ganymede may have been visible from Earth with the naked eye.

The second largest, Callisto, is one of the most heavily scarred objects in the Solar System. Its surface has changed little from its bombardment in the early days of the Solar System, making it useful for measuring conditions during that time period.

Io is the third largest moon, and the closest to Jupiter. The combined tidal forces of Jupiter itself on one side and the other three Gallilean moons from the other produces extreme friction that makes Io one of the Solar System's most volcanically active bodies.

The smallest Galilean moon, Europa, has become the most prominent to astronomers in recent years due to being considered the most likely place to find extraterrestrial life. The entire moon is covered by a sheet of ice that is between a mile and two miles thick depending on where you look. It is widely held that there is an ocean beneath the ice that may support simple aquatic life forms. For an added bonus, these life forms, if they exist, would be protected from Jupiter's radiation by the ice sheet. The ice sheet would also prevent them from picking up our broadcasts of I Love Lucy reruns, however. The existence of liquid water on Europa was confirmed in December of 2013 when the Hubble Space Telescope spotted a large geyser erupting from the moon. It remains unknown however, if there is indeed an ocean, or if there are just pockets of water.

[edit] Footnotes

  1. http://skeptoid.com/episodes/4143
  2. Geocide @ things of interest
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