orrery - n., an apparatus that illustrates the relative positions and motions of the planets of the solar system. (definition courtesy of WordNet).
this shockwave/flash orrery (not to scale), from dynamicdiagrams.com, is beautiful, spectacular and flexible: click on it; look at it.
look at your birth date; look at your birth date in an old-fashioned geocentric solar system, or at today, or whenever; see the zodiacal signs; set date; change speed; regard the myriad moons charging around! . . . or learn.
(also note the application name suggests it is a five-year-old design)
nasa's eyes on the solar system (which requires installation of a plug-in) is also quite breathtaking, albeit with a bit of a learning curve. be careful you don't get lost.