The Galilean Moons

ENV235Y1 Yin Chen (Judy) Jupiter – The Galilean Moons  Discovered by Italian Astronomer Galileo Galilei in 1609 using a new invention called telescope.

http://astronomyonline.org/SolarSystem/GalileanMoons.asp The Four Moons  The four moons of Jupiter are Callisto, Ganymede, Europa and Io. (From left to right)  All four moons keep one face towards Jupiter, called Tidal Locking.

http://astronomyonline.org/SolarSystem/GalileanMoons.asp Interiors of Galilean Moons  Io contains a large metals and silicate rock core, a mantle and a crust. (upper left)  Eruopa contains an icy crust, liquid ocean, mantle and a relatively smaller rocky core, possibly metallic. (upper right)  Ganymede contains 60% rock and 40% ice. (lower left)  Calisto may have a core, but very small. The interior may be just a mixture of about 50% water and 50% rocks. Formation of Jupiter

The distribution of the moons implies that the accretion disk around Jupiter was cool at the outer edge but hot near the planet. In the inner, hotter region of the disk, mostly silicates were available, while in the cool outer region water ice was abundant. Galilean moon -- Io  Io is 3,630 km in diameter and 421,600 km away from Jupiter.  Io orbits Jupiter in 1.77 days. (about 43 hours)  Its silicate mantle and crust are under constant tidal flex from Jupiter and the three other Galilean satellites. This result in constant violent eruptions of volcanoes. Additional energy generated by Erupa and Ganymede are the result of orbital resonance which is 1:2:4.  The “ tides” in the solid surface can rise 100 meters high generating enough heat for volcanic activity.  Io has more than 400 active volcanoes. Galilean moon -- Io • Colour of the surface is mostly Yellowish and orange. •The continually eruption and lava flows have resurfaced the terrain over billion of years. • Impact craters are buried by lava. •Traces of an extremely tenuous atmosphere have been detected, composed mostly of sulfur dioxide outgassed by volcanic eruptions. Galilean Moon -- Eruopa • Europa is 3,138 in diameter and is 670,900km away from Jupiter. Its shape is almost a perfect sphere. •The cracks are fractures in the ice as a result of tidal flexing from Jupiter. • May have an ocean with more than twice as much liquid water as all of Earth’s oceans combined. •The icy surface is nearly devoid of impact craters, so may be only a few million years old. Evidences of a possible liquid ocean

 The cracks appear to demonstrate the mineral hematite, which is a mineral resulting from the presence of liquid water. ( not yet confirmed)  Galileo spacecraft showed that Europa has a metallic core, which provides heat from the interior.  A magnetic field was detected, and is likely due to liquid water having a bit of salt.  Intense gravity from Jupiter causes “tidal flexing” which also provides heat to prevent freeze.  Presence of a very thin layer of atmosphere containing oxygen. (detected by the Hubble Space Telescope)  Lack of meteorite impact craters indicates active geology.  Life ? Eruropa

“Cracks” provides the best proof of an under surface activity that can only come from liquid.

Upwelling liquid Volcanism.

Liquid underneath brock through the surface Through some type of volcanic action, froze Crater Into this elevated lines. Europa Galilean moon -- Ganymede  Ganymede is 5,262 km in diameter and is 1,070,000 km away from Jupiter. It is the largest and heaviest moon in our Solar System.  Surface made of water ice. Darker regions are heavily cratered suggesting billions of years in age. Ganymede -- Surface  Ganymede’s surface is a mixture of two types of terrain.  40% of the surface of Ganymede is covered by highly cratered dark regions.  60% of the surface is covered by light grooved terrain, which forms intricate patterns across Ganymede.  The grooved is probably formed by tensional faulting or the release of water from beneath the surface. It can be as high as 700m.  Grooved terrain contains less craters, younger age. Ganymede

 Thin tenuous atmosphere comprised of oxygen and ozone are found.  Ozone is produced as charged particles penetrate the icy surface, further disrupted particles of water leading to ozone production. Ganymede

 Ganymede has a much weaker tidal force, thus weaker tidal heating than Europa and Io and not enough heat to make an ocean of liquid water.  Small amount of liquid water may lie underneath as evidence of geologic activity on the surface.  Strong magnetic field discovered by the Galileo probes. Its magnetic field is embedded inside Jupiter’s massive magnetoshpere. Galilean moons --- Callisto  Callisto is 4800 in diameter and is 1,883,800 km away from Jupiter.  It is the darkest of the Galilean moons, but twice as bright as Earth’s moon.  It has a surface age of about 4 billion years, the oldest land - scape in the solar system.  The surface of Callisto is described as “dirt ice” and is covered with an unknown dark mineral deposit. Callisto

 Callisto has a tenuous atmosphere composed of mostly carbon dioxide.  May be the gas emanates from the poles where solid CO2 formed.  It is described as a “dead world”, because there is no magnetic field and no geological activity and no atmosphere. Callisto

Valhalla Basin, one of the larger impact craters discovered. The multi- ring appearance is a result of the chock of impact. Large number of impacts. THE END Thank You!