Japanese head for the moon

Given all we know about distant planets and their moons, it is surprising that we still haven't got a definitive theory about where the moon came from. This morning, the Japan Aerospace Exploration Agency (JAXA) launched their Selenological and Engineering Explorer (SELENE) satellite. The satellite will orbit the earth a couple of times, and then head for the moon. After reaching the moon's orbit, it will launch two support satellites, and over the next year the satellite system will send back lunar topography and gravity data in unrivalled detail . This data is expected to firm up the 'giant impact' theory. According to this theory, a planetary body slammed into Earth 4.5-billion years ago, and the resulting debris eventually gathered to form the moon. link