Simplify the following text for a Grade 8 native English-speaking person.
Original: It was the last planetary satellite to be discovered by direct visual observation ( as opposed to photographically ) and was the first new satellite of Jupiter since Galileo Galilei 's discovery of the Galilean satellites in 1610 .
Simplified: It was the first new moon of Jupiter since Galileo Galilei 's discovery of the Galilean moons in 1610 .