Pope Benedict XVI waves to faithful at a welcome ceremony at the airport in Silao, Friday March 23, 2012. Benedict's weeklong trip to Mexico and Cuba is his first to both countries. (AP Photo/Dario Lopez-Mills)
VATICAN CITY (From CBS News) -- With a few words in Latin, Pope Benedict VXI did Monday what no pope has done in more than half a millennium, announcing his resignation and sending the already troubled Catholic Church scrambling to replace the leader of its one billion followers by Easter.
Not even his closest associates had advance word of the news, a bombshell that he dropped during a routine morning meeting of Vatican cardinals. And with no clear favorites to succeed him, another surprise likely awaits when the cardinals elect Benedict's successor next month.
"Without doubt this is a historic moment," said Cardinal Christoph Schoenborn, a protege and former theology student of Benedict's who is considered a papal contender. "Right now, 1.2 billion Catholics the world over are holding their breath."
The move allows for a fast-track conclave to elect a new pope, since the traditional nine days of mourning that would follow a pope's death doesn't have to be observed. It also gives Benedict great sway over the choice of his successor. Though he will not himself vote, he has hand-picked the bulk of the College of Cardinals -- the princes of the church who will elect his successor -- to guarantee his conservative legacy and ensure an orthodox future for the church.
The resignation may mean that age will become less of a factor when electing a new pope, since candidates may no longer feel compelled to stay for life.
"For the century to come I think that none of Benedict's successors will feel morally obliged to remain until their death," said Paris Cardinal Andre Vingt-Trois.
Benedict had said as recently as 2010 that a pontiff should resign if he got too old or infirm to do the job, but it was a tremendous surprise when he said in Latin that his "strength of mind and body" had diminished and that he couldn't carry on. He said he would resign effective 8:00pm Rome time on February 28th.
"All the cardinals remained shocked and were looking at each other," said Monsignor Oscar Sanchez of Mexico, who was in the room at the time of the announcement.
As a top aide, Benedict watched from up close as Pope John Paul II suffered publicly from the Parkinson's disease that enfeebled him in the final years of his papacy. Clearly Benedict wanted to avoid the same fate as his advancing age took its toll, though the Vatican insisted the announcement was not prompted by any specific malady.
The Vatican said Benedict would live in a congregation for cloistered nuns inside the Vatican, although he will be free to go in and out. Much of this is unchartered territory. The Vatican's chief spokesman, the Rev. Federico Lombardi, said he isn't even sure of Benedict's title -- perhaps "pope emeritus."
Since becoming pope in 2005, Benedict has charted a very conservative course for the church, trying to reawaken Christianity in Europe where it had fallen by the wayside and return the church to its traditional roots, which he felt had been betrayed by a botched interpretation of the modernizing reforms of the Second Vatican Council.
His efforts though, were overshadowed by a worldwide clerical sex abuse scandal, communication gaffes that outraged Jews and Muslims alike and, more recently, a scandal over leaked documents by his own butler. Many of his stated priorities as pope also fell short: he failed to establish relations with China, heal the schism and reunite with the Orthodox Church, or reconcile with a group of breakaway, traditionalist Catholics.
There are several papal contenders in the wings, but no obvious front-runner -- the same situation as when Benedict was elected after the death of John Paul. As in recent elections, some push is expected for the election of a Third World pope, with several names emerging from Asia, Africa and Latin America, home to half the world's Catholics.
CBS News correspondent Mark Phillips reports the highest profile potential candidate from Latin America may be the 63-year-old Archbishop of Sao Paolo Brasil, Cardinal Odilio Pedro Scherer. But the Church has yet to demonstrate it is ready for South American pope and he's thought to be a long shot. So is Cardinal Timothy Dolan, the charismatic Archbishop of New York who is well known internationally. Any American candidate would have to overcome the Church's tradition reluctance to elect a superpower pope, Phillips reports.
Retired American Cardinal Theodore McCarrick Phillips the Church will now be looking for a new pope with a combination of the qualities it liked in the last two.
"I think they will be looking for a man with some of the wisdom of Pope Benedict and some of the charisma of Pope John Paul II," McCarrick said.
The Church will likely look for a man as conservative as Benedict, as well. When CBS "Evening News" anchor Scott Pelley asked Dolan if a new leader could bring in a new era -- for example, for women in the church -- Dolan said extreme change was unlikely.
"The job description of the pope is to conserve," Dolan told Pelley. "You know, to conserve the patrimony of the faith. So it shouldn't surprise us, of course, that a pope would be conservative in the best sense of the word."
As early as 2010, Benedict began to look worn out: He had lost weight and didn't seem fully engaged when visiting bishops briefed him on their dioceses. But as tired as he often seemed, he would also bounce back, enduring searing heat in Benin to caress a child and gamely hanging on when a freak storm forced him to cut short a speech during a youth festival in Madrid in 2011.
His 89-year-old brother, Georg Ratzinger, said doctors recently advised the pope not to take any more trans-Atlantic trips.
"His age is weighing on him," Ratzinger told the dpa news agency in Germany. "At this age, my brother wants more rest."
Although popes are allowed to resign, only a handful has done it -- and none for a very long time.
The last pope to resign was Pope Gregory XII, who stepped down in 1415 in a deal to end the Great Western Schism, a dispute among competing papal claimants. The most famous resignation was Pope Celestine V in 1294; Dante placed him in hell for it.
There are good reasons why others haven't followed suit, primarily because of the fear of a schism with two living popes. Lombardi sought to rule out such a scenario, saying church law makes clear that a resigning pope no longer has the right to govern the church.
When Benedict was elected in 2005 at age 78, he was the oldest pope chosen in nearly 300 years. At the time, he had already been planning to retire as the Vatican's chief orthodoxy watchdog to spend his final years writing in the "peace and quiet" of his native Bavaria.
And by Easter Sunday, the Catholic Church will almost certainly have a new leader, Lombardi said - a potent symbol of rebirth in the church on a day that celebrates the resurrection of Christ.