Binoculars are not the usual observing tool for planets - even 25x100
astronomy binoculars lack the magnification needed for serious planet work. Strangely enough, though, you can have fun with any astronomy binocular or even a
birding binocular, with Jupiter's moons. The four largest of Jupiter's
moons - Ganymede, Callisto, Io and Europa - will appear as tiny stars in nearly any
binocular, lined up in a straight line on either side of the planet. The fun part is watching them switch positions from one side of the planet to the other, night to night, and there will be nights where you will not see all four, as one more may be obscured by Jupiter, itself. So which one is which? Get an issue of Astronomy or Sky&Telescope for the current month and check the pullout star map section. There will usually be a chart of Jupiter's moons showing the positions of each moon, night to night. For even more fun, read up on each moon and you will discover that each is a uniquely interesting world of its own and quite unlike our own moon.