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Jupiter - The Galilean Moons

From any telescope on Earth, a view of Jupiter and its four main moons are possible. Galileo Galilei, an Italian Astronomer, discovered the four moons of Jupiter in 1609 (along with the phases of Venus) using a new invention called a telescope.

More information can be found on the Galilean Moon Fact Sheet.

The discovery of the phases of Venus and the orbits of the four moons of Jupiter helped to add evidence of the Sun-centered Universe (heliocentric). For the longest time, scientists believed the Earth was at the heart of the Universe. We now know that we reside on the edge of an "average" spiral galaxy among a population of several galaxies that are members of the Universe - there is no center.

As seen from a small telescope on Earth, you may see Jupiter and its four main moons like this:

The four main moons of Jupiter are:

The image above shows, from left to right: Callisto, Ganymede, Europa, and Io. These sizes are accurate to each other. The orbits of the moons are seen below, and all four moons keep one face towards Jupiter - called Tidal Locking (like our Moon is tidal locked to the Earth).

Each of these satellites are different from each other. An example is the interiors:

The interior of Io (upper left) indicates a larger rock core, a mantle and crust. Europa(upper right) demonstrates an icy curst, a liquid ocean, a mantle and a smaller rocky core - possible metallic. Ganymede (lower left) is actually similar to Europa and may also possess a metallic core. Callisto (lower right) may have a core, but very small - the interior is thought to be water mixed with rock.

More details on each moon have been left to their own sections, but much of our knowledge is limited and will require further data analysis and collection.

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