With Benedict XVI's abdication taking effect Thursday, the Roman Catholic Church has no pope until the conclave of cardinals settles on a new one. Like many other procedures of the church, the rules for running the institution during this period are ancient and little-known. Here are answers to questions you might have about exactly what happens when the papacy changes hands:
Who's in charge now?
When a monarch leaves, the period before the new king or queen takes over is called an interregnum. In the Roman Catholic Church, it's called a sede vacante (or "empty seat"). The Cardinal Chamberlain, or Camerlengo — currently Vatican Secretary of State Tarcisio Bertone — is in charge of running the church, working with three cardinal assistants who are chosen at random and are replaced every three days.
Why did the pope use a helicopter?
Benedict headed off to a temporary retirement home at Castel Gandolfo, the summer papal retreat, while his permanent home on the Vatican grounds is renovated. To get there, he took a helicopter. Pope Paul VI started the tradition in 1975 purely for practical reasons: The ancient Appian Way — the only way to get there by car — is narrow and a traffic nightmare.
Benedict has a pilot's license, and he's been known to fly the chopper himself on visits to Castel Gandolfo. That didn't happen this time.
Who's going with him?
Benedict's private secretary, Archbishop Georg Gänswein, accompanies him to Castel Gandolfo and will continue as head of his household. At the same time, he'll continue to play an important role in the affairs of the new pope, an arrangement that has raised questions about the possible division of his loyalties. (As in all other matters, of course, the new pope could reassign Gänswein for any reason.)
Federico Lombardi, the Vatican's spokesman, said the arrangement was likely chosen for the sake of simplicity.
"I believe it was well thought out," he said.
Not staying with Benedict are the famous Swiss Guards. Regular Vatican police now are responsible for his security.
Why isn't Benedict going back to being a cardinal?
There's no modern precedent for what to do with a living ex-pope, so the Vatican has essentially been making new procedures on the fly.
According to the Vatican's Code of Canon Law, "cardinal" isn't actually a job. It's an honor bestowed upon a bishop or archbishop, which remains his formal job. When Joseph Ratzinger became Pope Benedict XVI, he ceased being a cardinal and assumed the duties of bishop of Rome. The new pope takes on that title. Hence the Vatican's decision to bestow upon Benedict the unprecedented honorific of "pope emeritus."
Does he get to keep the robe?
Yes, but not the red shoes or the ornamental fur fringe. Those are reserved for the active pope.
Although it's been widely reported that the red "shoes of the fisherman" are made by Prada, they're not, the Vatican says. They're made by the pope's personal cobbler. ("The Pope, in summary, does not wear Prada, but Christ," it said.) Regardless, they're still quite eye-catching: In 2007, Esquire listed Benedict among the world's best-dressed men — mainly for his red shoes. "The point is: Have a signature," it said.
Benedict also relinquished the gold "ring of the fisherman," which is personally made for every pope. In accordance with tradition, it's to be smashed with a silver hammer by Bertoni, the camerlengo, to keep it from being used to forge documents. Benedict's personal seal will be broken for the same reason.
What happens to @Pontifex?
Benedict was the first wired pope — the first to have an iPod, the first to have a cellphone (it's engraved with his coat of arms, the Vatican says) and the first to have a Twitter account.
This was Benedict's final tweet Thursday (because the account was wiped clean in preparation for its next user, there's no link):
Lombardi, the Vatican spokesman, said the @Pontifex handle will be turned over to the next pope, who may do with it whatever he pleases.
How do they make the black and white smoke?
Short answer: with difficulty.
After each vote of the papal conclave, the cardinals' ballots are burned. If the vote produces a new pope, the ballots are burned alone, which is supposed to produce a white smoke. If the vote's unsuccessful, a chemical compound is added that's supposed to turn the smoke black.
The official Vatican history says that traditionally, wet straw was used to produce black smoke, but that produced too many false alarms during the election of Pope John XXIII in 1958, so in 1963, the Vatican turned to science.
(Covering the gray-smoke mixup in 1958, The Associated Press wrote: "So great was the confusion on that Sunday — there were two false alarms — that conclave marshal Sigismondo Chigi told reporters he would have the cardinals briefed 'in the hope that something can be done to remedy the situation Monday.'" The Vatican says it will also ring bells this time to make it clearer when a new pope is chosen.)
Does the pope have to take a new name?
Not necessarily; it's an ancient tradition, not a law. Until 533, popes used their own names. But that year, a priest named Mercurius of Rome was elected. He was named for the Roman god Mercury, which was obviously inappropriate for the leader of the Christian church, so he took the name John II. (The Catholic Encyclopedia notes that "the basilica of St. Clement still retains several memorials of 'Johannes surnamed Mercurius.'")
Almost every pope since then has adopted a so-called regnal name.
Lou Dubois and Mary Lou Ahern of NBC News contributed to this report.