Luna Lovegood is your Potter character. She's a little batty, but loveable.
Okay, so why the lunar-crazy connection? The moon was seen as mysterious, even mystical to early civilizations. Something as weird as this huge, glowing orb hanging in the sky *must* have influence over us. The reasoning went that as the moon got bigger (approached full) so must its influence over people. Madness was seen as one result of being overly sensitive to the moon's influence, hence the words "lunacy" and "loonie".
Okay, so why the lunar-crazy connection? The moon was seen as mysterious, even mystical to early civilizations. Something as weird as this huge, glowing orb hanging in the sky *must* have influence over us. The reasoning went that as the moon got bigger (approached full) so must its influence over people. Madness was seen as one result of being overly sensitive to the moon's influence, hence the words "lunacy" and "loonie".