The precise thicknesses of this and other layers in the

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Jupiter Moon Ganymede

In 1610, Galileo Galilei looked up at the night sky through a telescope of his own design. Spotting Jupiter, he noted the presence of several “luminous objects” surrounding it, which he initially took for stars. In time, he would notice that these “stars” were orbiting the Canada Goose sale planet, and realized that they were in fact Jupiter’s moons which would Canada Goose Outlet come to be named Io, Europa, Ganymede and Callisto.

Canada Goose Online Of these, canada goose black friday sale Ganymede is the largest, and boasts many fascinating characteristics. In canada goose deals addition to being the largest moon in the Solar System, it is also larger than even the planet Mercury. It is the only satellite in canada goose store the Solar System known to possess a magnetosphere, has a thin oxygen atmosphere, and (much like its fellow moons, Europa and Callisto) is believed to have an interior ocean. Canada Goose Online

Canada Goose Coats On Sale Discovery and Naming: Canada Goose Coats On Sale

Though Chinese astronomical records claim that astronomer Gan De may have spotted a moon of Jupiter (probably Ganymede) with the naked eye as early as 365 BCE, Galileo Galilei is credited with making the first recorded observation of Ganymede on January 7th, 1610 using his telescope. Together with Io, Europa and Callisto, he named them buy canada goose jacket cheap the “Medicean Stars” at the canada goose clearance time after his patron, the Grand Duke of Tuscany, Cosimo de’ Medici.

Simon Marius, a German astronomer and contemporary of Galileo’s who claimed to have independently discovered Ganymede, canada goose clearance sale suggested alternative names at the behest of Johannes Kepler. However, the names of Io, Europa, Ganymede and Callisto which were all taken from classical mythology would not come to formally be adopted until the 20th century.

Canada Goose online Illustration of Jupiter and the Galilean satellites. Credit: NASAPrior to this, the Galilean Moons were named Jupiter I through IV based on their proximity to the planet (with Ganymede designated as Jupiter III). Following the discovery of the moons of Saturn, a naming system based on that of Kepler and Marius was Canada Goose online used for Jupiter’s moons. In Greek mythology, Ganymede was the son of King Tros (aka. Ilion), the namesake of the city of Troy (Ilium). Canada Goose online

Size, Mass and Orbit:

canada goose uk black friday With a mean radius of2634.1 0.3 kilometers (the equivalent of 0.413 Earths), Ganymede is the largest moon in the Solar System and is even larger than the planet Mercury. However, with a mass of 1.4819 x 10 kg (the equivalent of 0.025 Earths), it is only https://www.canadagoosepark.com half as massive. This is due to Ganymede’s composition, which consists of water ice and silicate rock (see below). canada goose uk black friday

Ganymede’s orbit has a minor eccentricity of 0.0013, with an average distance (semi major axis) of 1,070,400km varying from 1,069,200km at periapsis to at 1,071,600 km apoapsis. Ganymede takes seven days and three hours to completes a single revolution. Like most known moons, Ganymede is tidally locked, with one side always facing toward the planet.

uk canada goose Its orbit is inclined to the Jovian equator, with the eccentricity and inclination changing quasi periodically due to solar and planetary gravitational perturbations on a timescale of centuries. These orbital variations cause the axial tilt to vary between 0 and 0.33. Ganymede has a 4:1 orbital resonance with Io and a 2:1 resonance with Europa. uk canada goose

Ganymede is the largest satellite in our solar system, larger than Mercury and Pluto, and three quarters the size of Mars. Credit: NASA/JPLEssentially, this means that Io orbits Jupiter four times (and Europa twice) for every orbit made by Ganymede. The superior conjunction between Io and Europa occurs when Io is at periapsis and Europa is at apoapsis, and the superior conjunction between Europa and Ganymede occurs when Europa is at periapsis. Such a complicated resonance (a 4:2:1 resonance) is called the Laplace Resonance.

canada goose clearance Composition and Surface Features: canada goose clearance

Canada Goose Jackets With an average density of 1.936g/cm3, Ganymede is most likely composed of equal parts Canada Goose Jackets rocky material and water ice. It is estimated that water ice constitutes 46 50% of the moon’s mass (slightly lower than that of Callisto) with the possibility of some additional volatile ices such as ammonia being present. Ganymede’s surface has an albedo of about 43%, which suggests that water ice makes up a mass fraction of 50 90% the surface. Canada Goose Jackets

Near infrared and ultra violet surveys have also revealed the presence of carbon dioxide, sulfur dioxide, and possibly cyanogen, hydrogen sulfate and various organic compounds. More recent data has shown evidence of cheap canada goose jackets salts such as magnesium sulfate and possibly sodium sulfate, which may have originated from the subterranean ocean (see below).

canadian goose jacket Ganymede’s interior appears to be fully differentiated, consisting of a solid inner core made of iron, a liquid iron and iron sulfide outer core, a silicate mantle, and a a spherical shell of mostly ice surrounding the rock shell Canada Goose Parka and the core. The core is believed to measure 500 km in radius, and has a temperature of about 1500 1700 K and pressure of up to 10 GPa. canadian goose jacket

canada goose coats Artist’s cut away representation of the internal structure of Ganymede, with layers shown to scale. Credit: Wikipedia Commons/kelvinsongThe most compelling evidence for the existence of a liquid, iron nickel rich core is Ganymede’s intrinsic magnetic field. canada goose coats

This mantle is composed of silicate materials, most likely chondrites and iron. The outer ice shell is the largest layer of all, measuring an estimated 800 canadian goose jacket km (497 miles) thick. The precise thicknesses of this and other layers in the interior of Ganymede depends on the assumed composition of silicates and amount of sulfur in the core.

canada goose factory sale Scientists also believe that Ganymede has a thick ocean nestled between two layers of ice a tetragonal layer between it and the core and a hexagonal layer above it. The presence of this ocean has buy canada goose jacket been confirmed by readings taken by orbiters and through studies of how Ganymede’s aurora behaves. In short, the moon’s auroras are affected by Ganymede’s magnetic field, which in turn is affected by the presence of a large, subsurface salt water ocean. canada goose factory sale

Canada Goose Outlet Ganymede’s surface is a mix of two types of terrain. There’s the very old, highly cratered, and dark regions, and the somewhat younger, lighter regions marked with an extensive array of grooves and ridges. In a way that is similar to Europa, Ganymede’s surface is asymmetric, with the leading hemisphere being brighter than the trailing one. Canada Goose Outlet

The dark terrain, which comprises about one third of the surface, is so colored because the surface ice in these regions contains clays and organic materials. It has been theorized that these have been left behind by impactors, which accords with the fact that impact craters are far more extensive in the areas of dark terrain.

Meanwhile, the grooved terrain is believed to be tectonic in nature; which could be due in part to cryovolcanism, but is thought to be mostly the result of tidal heating events. The tidal flexing could have heated the interior and strained the lithosphere, leading to the development of cracks, graben and faults that erased the old, dark terrain on 70% of the surface.

Though craters are more common in the darker areas, they are seen all over the surface. Ganymede may have experienced a period of heavy cratering 3.5 to 4billion years ago similar to that of the Moon. If true, the vast majority of impacts happened in that epoch, whereas the cratering rate has been much smaller since. Craters on Ganymede are also flatter than those on the Moon and Mercury, which is probably due to the relatively weak nature of Ganymede’s icy crust.

canada goose Ganymede also has polar caps, likely composed of water frost, which were first seen by the Voyager spacecraft. Since the discovery, several theories have been proposed for their formation, ranging from the thermal migration of water vapor to higher latitudes to plasma bombardment turning the ice brighter. Also similar to Europa is how the atmosphere formed, which involves water ice on the surface being split into hydrogen and oxygen through interaction with UV radiation, the hydrogen being lost to space and the oxygen being retained. The surface pressure of this atmosphere is thought to lie within cheap Canada Goose the range of 0.2 1.2 micro Pascals. canada goose

Canada Goose sale Montage showing New Horizons’ views of Ganymede taken by it’s infrared spectrometer and LORRI and LEISA instruments. Credit: canada goose NASA/Johns Hopkins University APL/SwRIThe presence of this atmosphere also causes an airglow effect, a faint emission of light caused by the interaction of atomic oxygen and energetic particles. This effect is not uniformly distributed (as with Europa), but instead causes bright spots to appear above the polar regions which could be “polar auroras” due to the planet’s magnetic field. Canada Goose sale

Additional evidence of the oxygen atmosphere comes from the detection of various gases trapped in the canada goose coats on sale ice on Ganymede. This evidence consisted of the spectroscopic detection of ozone (O), as well as absorption features that indicated the presence of oxygen gas (O). Another constituent of the atmosphere is hydrogen, which (despite most being lost to space) still exists at a surface in very minor concentrations.

buy canada goose jacket cheap The existence of this neutral atmosphere implies that an ionosphere should exist since oxygen molecules are ionized by the impacts of the energetic electrons coming from the magnetosphere and by solar electromagnetic UV radiation. However, the existence of an ionosphere remains controversial, due to conflicting data gathered by different missions buy canada goose jacket cheap.