This
paper explains that Jupiter, which has a
mass of 1.900e27 kg., has more than twice the mass of all the other planets'
masses combined and is over 300 times the
mass of the Earth. The author points out that, when observing from Earth, Jupiter can best be seen when it is near its solar opposition, which is where Jupiter and the Earth are both aligned on the same side of the sun; Jupiter rises at Earth's sunset and sets at Earth's sunrise thereby being visible all during the night hours. The
paper relates that the first space probe to Jupiter was Pioneer 10 in 1973, followed by Pioneer 11, Voyager 1, Voyager 2 and Ulysses; the spacecraft Galileo is currently orbiting, sending data for at least two more years as it continues to orbit Jupiter.