VATICAN CITY — Argentine Cardinal Jorge Mario Bergoglio was elected the first non-European pope in more than 1,000 years on Wednesday, signaling the beginning of a new era for a church combating scandal and internal strife.

Described as a conservative with "great compassion," the 76-year-old will be known as His Holiness Pope Francis. He will be installed at the Vatican on Tuesday.

The new pontiff named himself after the humble Catholic friar St. Francis of Assisi. President Barack Obama hailed the new leader of the world's 1.2 billion Catholics as a "champion of the poor."

The first Latin American pope was introduced from the balcony of St. Peter’s Basilica.

There was an audible gasp from the rain-soaked crowd - an indication that he had not been a widely tipped choice - followed by a roar and wild applause.

In Italian, he seemed to address his outsider status by joking: "As you know the duty of the conclave is to give Rome a bishop. It seems that my brother cardinals went almost to the end of the world."

“Pray for me and I will see you soon," he added, asking Catholics to also pray for his predecessor Benedict XVI, who abdicated on Feb. 28. "Have a good evening and rest well.”

His first act on Thursday will be to visit his predecessor, the Pope Emeritus, New York Cardinal Timothy Dolan told reporters later.

A vocal advocate for Argentina’s poor during the economic crises that struck the country during the 1970s, Francis is the first Jesuit pope.

Vote: Was Pope Francis a good choice?

Known for his humility, Francis is the son of a railway worker and one of five siblings. He has a chemistry degree.

Francis has only one fully-functioning lung, the other having been partially removed due to an infection when he was a teenager. 

He prizes simplicity and is expected to encourage priests to do shoe-leather evangelization, according to his biographer.

Shortly after his election, Francis skipped the limousine and chose instead to ride on the last shuttle bus with other cardinals to go back to the Vatican for a meal.

"And as the last bus pulls up, guess who gets off? It's Pope Francis. I guess he told the driver 'That's OK, I'll just go with the boys,'" Dolan told reporters.

Later, during the dinner, Dolan said Francis showed his humorous side.

"We toasted him and when he toasted us he said: 'May God forgive you,' which brought the house down," he said.

About an hour before Francis emerged on the balcony, white smoke rose above the Sistine Chapel and bells rang out across Rome to signal a decision had been made.

The unveiling of the new pope was moment of pure joy for the 100,000 pilgrims, tourists and other onlookers in St Peter's Square.  

"Who is this?" asked Deirdre Sweeney from Boston, Mass., when Francis first walked onto the balcony.

"Argentinian!" shouted a man nearby.

 “I think this is wonderful,” said Sweeney’s husband, Kevin. “It's an incredible breakthrough. It's a great recognition for the church that the church is not euro-centric anymore."

Another man shouted: "It’s very gutsy that he chose the name Francis, he’s going to be the first Francis. He wants to be a humble pope and build the church up, from a time of ruin, like St. Francis of Assisi."

Smoke billowed from the chimney at 7:07 p.m. local time (2:07 p.m. ET) on the second day of behind-closed-doors voting.

The cardinals are thought to have taken five ballots to reach the two-thirds of the vote necessary for a decision.

The new pontiff's debut was heralded by a Latin announcement beginning with the phrase "Habemus Papam!" meaning, "We have a pope!"

George Weigel, NBC News' Vatican analyst, said Francis would be "a great defender of religion around the world.”

“The papacy has moved to the New World. The church has a new pope with a new name,” he added. “I think it speaks to the church’s commitment to the poor of the world and compassion in a world that often needs a lot of healing.”

Obama said the choice of the first pope from the Americas spoke "to the strength and vitality" of a region "that is increasingly shaping our world."

"Alongside millions of Hispanic Americans, those of us in the United States share the joy of this historic day," the president said in a statement.

Now known as Pope Emeritus, Francis' predecessor Benedict watched Wednesday's events from a temporary lakeside residence at Castel Gandolfo while his permanent living quarters inside Vatican City are refurbished.

The behind-the-scenes ballot process that took place in the Sistine Chapel should still remain a secret. Both the cardinals and staff working alongside them swore an oath of secrecy as the conclave got under way, with the threat of ex-communication for anyone breaking the church's ancient code.

NBC News' Yuka Tachibana and Richard O'Kelly, and Reuters contributed to this report.

Slideshow: Pope Francis I: His life before the papacy

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Cardinal Jorge Bergoglio of Argentina was elected to lead the Catholic Church following the resignation of Pope Benedict XVI. 

Launch slideshow

Related: 

Pope Francis: Humble leader who takes the bus to work

'He’s not feeble in any way': World reacts to a new pontiff

Full coverage of Pope Francis from NBC News

This story was originally published on Wed Mar 13, 2013 4:14 AM EDT

Alessandro Bianchi / Reuters file

Cardinal Tarcisio Bertone, the cardinal chamberlain, or camerlengo, will officially be in charge of Vatican affairs until a new pope is elected.

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.)

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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):

Twitter.com

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.

Related:

• Cheers and tears as Benedict flies to temporary home in hilltop town
• Inside Castel Gandolfo, Pope Benedict's spectacular temporary retirement home
• How the pope's retirement package compares to yours