Had he lived to what would have been his 75th birthday on Monday, Carl Sagan would've seen a surprising new collaborator in pondering whether there's life out there in the cosmos: the Vatican. The Pontifical Academy of Sciences held a conference of scientists and theologians this week that probed the possibility of extraterrestrial life, and the peculiar religious questions that life on other worlds would raise. Father Jose Funes, director of the Vatican Observatory, became the Catholic Church's chief evangelist this week spreading the notion that alien life is compatible with Christianity.