... Tonight's Sky . ... Sky this Month . ... Ganymede's magnetosphere makes a big impression on Jupiter's auroral lightshows . ... These waves are projected along Jupiter's magnetic field lines toward Jupiter's poles, where they cause auroral bright spots. ... Uniquely among Jupiter's moons, Ganymede has a strong enough magnetic field to carve a protective magnetic bubble within Jupiter's powerful magnetosphere. ... Only registered members of Astronomy.com are allowed to comment on this article. ...