Supposing the human race were to colonize Mars, as many sci-fi buffs often propose we should – what would the theological or religious ramifications be? Certainly it would be strange for Muslims, who might not know exactly how to face Mecca when praying – however, Christian prayer faces the rising of the sun, and that can in principle, it seems, be done on any planet which we would choose to colonize (almost as though that attention to ‘cosmic’ liturgy makes Christianity more liturgically adaptable than Islam). Imagine the ramifications for liturgy if our days were significantly longer or shorter on another planet – what would become of the obligation to attend Sunday Mass? What would become of the liturgical calendar itself if it requires ‘days’ according to the ‘rising and setting’ of the sun? Would the Latin rite divide into more than one rite based on what planet the churches were on? What would be the status of the Bishop of Mars in the eyes of the Catholic faithful? Can anyone imagine a second ‘protestant reformation’ happening not from one country to another, but from one planet to another?