History UsefulNotes / TheMoonsOfJupiter

Io was the setting for the movie ''Film/{{Outland}}'', is also the homeworld of Arnold Judas Rimmer, from ''Series/RedDwarf'', and hosts a series of racetracks in ''VideoGame/{{Redout}} II''. The radiation levels may explain much about the Rimmer family, especially Arnold. Also the last world [[VideoGame/Destiny2 touched by the Traveler.]] In the EdutainmentGame ''VideoGame/TheMagicSchoolBus Explores the Solar System'', Io is where you make your landing when you travel to Jupiter.

Io was the setting for the movie ''Film/{{Outland}}'', and is also the homeworld of Arnold Judas Rimmer, from ''Series/RedDwarf''. The radiation levels may explain much about the Rimmer family, especially Arnold. Also the last world [[VideoGame/Destiny2 touched by the Traveler.]] In the EdutainmentGame ''VideoGame/TheMagicSchoolBus Explores the Solar System'', Io is where you make your landing when you travel to Jupiter.

About 3640 km in diameter, Io is one of the Galilean moons. Slightly larger than our moon, its relatively close orbit to Jupiter means that it is the largest moon as seen from the surface of its parent planet in the solar system.

About 3640 km in diameter, Io is one of the Galilean moons.

-->-- ''[[Film/TwoThousandTenTheYearWeMakeContact 2010: Odyssey Two]]'' (The addition comes from [[Film/TwoThousandTenTheYearWeMakeContact the film version]] of the novel.)

-->-- ''[[Film/TwoThousandTenTheYearWeMakeContact 2010: Odyssey Two]]'' (The addition comes from the film version of the novel.)

Despite being larger than Mercury, Ganymede isn't as dense. It's less than half of Mercury's mass[[labelnote:*]]45%, specifically[[/labelnote]], and its surface gravity is only 14.6% of Earth's. (Mercury, by contrast, has 38% of Earth's surface gravity, the same as the surface gravity on {{UsefulNotes/Mars}}.)

Four irregular shaped moons, being pretty small and not large enough to form into spheres. Due to tidal forces, the first two will eventually drop into the planet or break up into ring particles. The largest, Amalthea, was discovered in 1892 and is very, very red. The radiation levels this close to {{UsefulNotes/Jupiter}} ''will'' kill you faster than you can say "non-functional DNA".

!!Space Pizza: Io

!!Ice World: Europa

!!Big Brother: Ganymede

!!Bullseye: Callisto

Almost as big as {{UsefulNotes/Mercury}} and the third biggest moon in the Solar System, this dead world is outside the main radiation belts of {{UsefulNotes/Jupiter}} and is the outermost Galilean moon. At larger scales it's covered by craters on top of other craters. At smaller scales, the surface shows more variety, with plains and knobs, probably formed by the erosion of yet more craters. The general calmness of the place (0.01 rem/day average) makes it a good location to colonize, but most writers tend to ignore it. In fact, it has ''seven times less'' radiation than even our own Earth. Callisto is the only Galilean moon not part of an orbital resonance with the others. Due to the resulting lack of tidal forces from the other three Galilean moons, Callisto's surface has remained largely unchanged since it was bombarded in the early days of the Solar System, making it a valuable source of information about the conditions of that time. This lack of tidal heating also makes Callisto the largest non-differentiated body in the Solar System.

Io was the setting for the movie ''Film/{{Outland}}'', and is also the home planet of Arnold Judas Rimmer, from ''Series/RedDwarf''. The radiation levels may explain much about the Rimmer family, especially Arnold. Also the last planet [[VideoGame/Destiny2 touched by the Traveler.]] In the EdutainmentGame ''VideoGame/TheMagicSchoolBus Explores the Solar System'', Io is where you make your landing when you travel to Jupiter.

The first four to be found (Io, Europa, Ganymede and Callisto) were discovered by Galileo himself, and thus are called the Galilean Moons. They dealt a significant blow to the notion that the Earth was the center of the universe, although [[CommonKnowledge contrary to popular belief]] they did not disprove the idea altogether; the existence Jupiter's moons did not have any bearing on the question of whether Jupiter itself orbited the Earth. Galileo [[YesMan wanted to name them after his patrons]], the Medicis, but later generations of astronomers thought otherwise. One night after Galileo discovered them, a German by the name of Simon Marius — who'd independently gotten the idea of pointing a telescope at the heavens — also saw the same 4 moons, and named them after four of {{UsefulNotes/Jupiter}}'s lovers from Myth/ClassicalMythology; it's these names that are still in use today.

The discovery of the four Galilean moons was a major blow to the geocentric model of the universe, Until Isaac Newton defined his Laws of Gravity, it was widely held that Earth could not revolve around the Sun because the Moon would be left behind. Once it was observed that Jupiter was clearly dragging four objects along its orbit, it raised the question of why Earth couldn't do the same with the Moon. (That being said, it wasn't definitive proof; there was also strong evidence that while the planets revolved around the Sun, the Sun and Moon might revolve around the Earth. Solid proof of the Sun-centered Solar System would not come until the 19th century, when astronomers measured parallax in a star that showed the stars to be super-far away. By that point, most astronomers had accepted heliocentrism, but they were basing it on a sense that that solution, which was more elegant, was more likely true, rather than solid evidence.)

The largest moon in UsefulNotes/{{the Solar System}}. Larger than {{UsefulNotes/Mercury}}, it could count as a planet on its own if it weren't already attached to one. Its surface shows evidence of past geological activity. A popular sci-fi (and one-off ''Series/PowerRangersInSpace'') setting, even if it is really just a bigger version of our {{UsefulNotes/the Moon}}, in other words, deader than tanktops. In ''Series/PowerRangersInSpace'', it is shown that Zordon hid the components of the Mega Voyager Zord here in case of emergencies. The radiation here (8 rem/day) won't kill you directly, but you might want to invest in a surrogate gamete donor (those eggs and sperm cells spoil easy!) or an MRI machine (so you can get a cancer scan every six months or so).

Due to it's interesting status in the solar system, Europa has been the subject of many proposed probe launches to study or even drill into its surface. Most famous was probably the joint ESA/NASA [[https://en.wikipedia.org/wiki/Europa_Jupiter_System_Mission_%E2%80%93_Laplace Europa Jupiter System Mission – Laplace]] (EJSM/Laplace) that unfortunately never got of the planning stage. Or at least not in its original context, as both NASA and ESA has probes planned to jointly study the moon with the [[https://en.wikipedia.org/wiki/Jupiter_Icy_Moons_Explorer Jupiter Icy Moons Explorer]] and the [[https://en.wikipedia.org/wiki/Europa_Clipper Europa Clipper]]. Both of which will make several flybys at around 2029 and 2026-31 respectively depending on launch window.

It is the only moon known to produce its own magnetic field. The second strongest of any rocky body in fact and roughly 3% of that of Earth's; which sounds about right since it has 2.5% of earth's mass. The origin of the field and why similar moons don't have one we have no idea, but it might suggest the presence of a liquid iron core similar to that of earth's that's kept in such a state by the same tidal forces that keeps Europa's ocean from freezing. The moon would probably also have some really spectacular auroras as the field interacts with the Jovian plasma.

It is the only moon known to produce its own magnetic field. The second strongest of any rocky body in fact and roughly 3% of that of Earth's; which is impressive since it only has 0.025% of earth's mass. The origin of the field and why similar moons don't have one we have no idea, but it might suggest the presence of a liquid iron core similar to that of earth's that's kept in such a state by the same tidal forces that keeps Europa's ocean from freezing. The moon would probably also have some really spectacular auroras as the field interacts with the Jovian plasma.

The first four to be found (Io, Europa, Ganymede and Callisto) were discovered by Galileo himself, and thus are called the Galilean Moons. They dealt a significant blow to the notion that the Earth was the center of the universe, although [[CommonKnowledge contrary to popular belief]] they did not disprove the idea altogether; the existence Jupiter's moons did not have any bearing on the question of whether Jupiter itself orbited the Earth. The discovery of moons that orbited a planet other than Earth destroyed the primary argument for why Earth needed to be stationary. Prior to the work of UsefulNotes/IsaacNewton, one of the primary arguments used by geocentrists was our own Moon would be left behind if Earth was not stationary. Once it was established that Jupiter was carrying multiple objects along its orbital path, it raised the question of why Earth could not do the same. Galileo [[YesMan wanted to name them after his patrons]], the Medicis, but later generations of astronomers thought otherwise. One night after Galileo discovered them, a German by the name of Simon Marius — who'd independently gotten the idea of pointing a telescope at the heavens — also saw the same 4 moons, and named them after four of {{UsefulNotes/Jupiter}}'s lovers from Myth/ClassicalMythology; it's these names that are still in use today.

The first four to be found (Io, Europa, Ganymede and Callisto) were discovered by Galileo himself, and thus are called the Galilean Moons. They disproved any remaining notions that the Earth was the center of the universe. Galileo [[YesMan wanted to name them after his patrons]], the Medicis, but later generations of astronomers thought otherwise. One night after Galileo discovered them, a German by the name of Simon Marius — who'd independently gotten the idea of pointing a telescope at the heavens — also saw the same 4 moons, and named them after four of {{UsefulNotes/Jupiter}}'s lovers from Myth/ClassicalMythology; it's these names that are still in use today.

* Notable Features: Conamara Chaos, Possible Sub-surface Ocean

* Axial Tilt: 0° to Orbital Plane, 3° to Jupiter's Equator

* Axial Tilt: 0° to Orbital Plane, 3° to Jupiter's Equator

* Axial Tilt: 0° to Orbital Plane, 3° to Jupiter's Equator

* Axial Tilt: 0° to Orbital Plane, 3° to Jupiter's Equator

Due to it's interesting status in the solar system, Europa has been the subject of many proposed probe launches to study or even drill into its surface. Most famous was probably the joint ESA/NASA [[https://en.wikipedia.org/wiki/Europa_Jupiter_System_Mission_%E2%80%93_Laplace Europa Jupiter System Mission – Laplace]] (EJSM/Laplace) that unfortunately never got of the planning stage. Or at least not in its original context, as both NASA and ESA has probes planned to jointly study the moon with the [[https://en.wikipedia.org/wiki/Jupiter_Icy_Moons_Explorer Jupiter Icy Moons Explorer]] and the [[https://en.wikipedia.org/wiki/Europa_Clipper Europa Clipper]]. Booth of which will make several flybys at around 2029 and 2026-31 respectively depending on launch window.

* Orbital Period: 42 Hours
* Rotational Period: 42 Hours (Tidally Locked, 1:1 Laplace Resonance with Europa and Ganymede)

* Orbital Period: 3 Days
* Rotational Period: 3 Days (Tidally Locked, 2:1 Laplace Resonance with Io and Ganymede)

Due to it's interesting status in the solar system, Europa has been the subject of many proposed probe launches to study or even drill into its surface. Most famous was probably the joint ESA/NASA [[https://en.wikipedia.org/wiki/Europa_Jupiter_System_Mission_%E2%80%93_Laplace Europa Jupiter System Mission – Laplace]] (EJSM/Laplace) that unfortunately never got of the planning stage. Or at least not in it's original context, as Booth NASA and ESA has probes planned to jointly study the moon with the [[https://en.wikipedia.org/wiki/Jupiter_Icy_Moons_Explorer Jupiter Icy Moons Explorer]] and the [[https://en.wikipedia.org/wiki/Europa_Clipper Europa Clipper]]. Booth of which will make several flybys at around 2029 and 2026-31 repectivly depending on launch window.

* Orbital Period: 7 Days
* Rotational Period: 7 Days (Tidally Locked, 4:1 Laplace Resonance with Europa and Io)

The largest moon in UsefulNotes/{{the Solar System}}. Larger than {{UsefulNotes/Mercury}}, it could count as a planet on its own if it weren't already attached to one. Its surface shows evidence of past geological activity. A popular sci-fi (and one-off ''Series/PowerRangersInSpace'') setting, even if it is really just a bigger version of our {{UsefulNotes/the Moon}}, in other words, deader than tanktops. In ''Series/PowerRangersInSpace'', it is shown that Zordon hid the components of the Mega Voyager Zord here in case of emergencies. The radiation here (8 rem/day) won't kill you directly, but you might want to invest in a surrogate gamete donor (those eggs and sperm cells spoil easy!) or an MRI machine (so you can get a cancer scan every six months or so). Also has an under-ice ocean which is probably good for colonization, but the ice crust is thicker, perhaps too thick to drill.

It is the only moon known to produce its own magnetic field, and its surface features are named after locations and [[Myth/EgyptianMythology myths]] of AncientEgypt and Mesopotamia (Tiamat Sulcus, Memphis Facula, etc.). Many of these features are tectonic, possibly formed by tidal heating or by expansion of the moon. Most features, tectonic or crater, appear to have formed several billion years ago over roughly the same time.

It was discovered March 2015 that Ganymede has a subsurface ocean like Europa. This was discovered by measuring Ganymede's aurora: normally, an aurora is very wobbly, but Ganymede's aurora is stable, which is only possible in the presence of a large quantity of salt water.

Io was the setting for the movie ''Film/{{Outland}}'', and is also the home planet of Arnold Judas Rimmer, from ''Series/RedDwarf''. The radiation levels may explain much about the Rimmer family, especially Arnold. Also the last planet [[VideoGame/Destiny2 touched by the Traveler.]]

Io was the setting for the movie ''Film/{{Outland}}'', and is also the home planet of Arnold Judas Rimmer, from ''Series/RedDwarf''. The radiation levels may explain much about the Rimmer family, especially Arnold.