Ramadan does not move in the Islamic year, but they use the Hijri Calendar which has 11 days a year missing so to anyone using the proper calendar it appears to move. Diwali has a similar problem in that it uses a similarly inaccurate Hindu Lunisolar calendar. Easter moves for a different reason, It's the Sunday after the first full moon after the Vernal Equinox.
Theland; and to digress a little, do you think that there might be life on other planets, and if so do you think that they might have religions and festivals, and if so do you think that they are all wrong because they aren't in your religion?