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Satellites of Jupiter
On 7th February
1610 Galileo observed Jupiter with his refractor and noticed a
motion of three and – lately – four objects around the planet! He
realized that they behave similarly to the Moon, when it goes round
the Earth. Those objects were the four biggest satellites of
Jupiter. Deeply moved Galileo, told the world about his
discovery.
But the Catholic
Church - desired the Earth to stay safe in the favourite, central
point of the Universe - made Galileo deny the conclusions, the
scientist drew from his observations. The four biggest satellites
of Jupiter were discovered in 1610 by Simon Marius, as
well.
The family of the
Jupiter’s moons is very large. The composition of this group
consists of very many interesting objects. The most famous are: Io,
Europa, Ganymede and Callisto discovered in 1610 and named:
Medicean stars (or planets) by Galileo. Johannes Kepler
suggested calling them the satellites. Lately the moons were
named with the names of the Jupiter-god’s “sweethearts”. I should
explain that: Io, Europa and Callisto are the female names.
Ganymede was kidnapped and became the cup-bearer of the
gods.
The
four Galilean moons in order of their growing distance from
Jupiter: Io, Europa, Ganymede, Callisto. Photographed by the
Galileo probe.
The moons go round
the Jupiter along the circular orbits in the planet’s equatorial
plane. Their sizes are approximately the same as size of the Moon
and they also turn to the planet the same side all the time. The
satellites have the 6m brightness and they can be
observed by the binoculars.
In my opinion, the
most interesting moons in the Jupiter’s family – or even in the all
solar system – are the ice Europa and the fiery Io. At Europa there
are oceans probably, where an organic life may exist. At Io a
volcanic activity was observed. Ganymede is the biggest moon in our
solar system – it is bigger than Mercury and Pluto!
