<P> Io ( Jupiter I ) is the innermost of the four Galilean moons of Jupiter and , with a diameter of 3642 kilometers , the fourth - largest moon in the Solar System . It was named after Io , a priestess of Hera who became one of the lovers of Zeus . Nevertheless , it was simply referred to as `` Jupiter I '' , or `` The first satellite of Jupiter '' , until the mid-20th century . </P>
<P> Io ( Jupiter I ) is the innermost of the four Galilean moons of Jupiter and , with a diameter of 3642 kilometers , the fourth - largest moon in the Solar System . It was named after Io , a priestess of Hera who became one of the lovers of Zeus . Nevertheless , it was simply referred to as `` Jupiter I '' , or `` The first satellite of Jupiter '' , until the mid-20th century . </P>
of the four galilean moons which is the closest to jupiter
of the four galilean moons which is the closest to jupiter
Io
Io