The former archbishop of Buenos Aires, Cardinal Jorge Bergoglio, entered the St. Mary Major basilica through a side entrance just after 8am and left about 30 minutes later. He had told a crowd of some 100,000 people packed in rain-soaked St. Peter's Square just after his election that he intended to pray to the Madonna "that she may watch over all of Rome." As he begins his papacy he will be granted a few hours if not days to deal with his personal needs and private obligations, before being plunged into the practical realities of being Pontiff. Pope Francis will celebrate the first day of his reign by taking mass with the cardinals before setting out his vision for his papacy. With Holy Week, the busiest week of the year for a pope, just around the corner the newly elected head of the Catholic church will have packed itinerary. Last night, a rain-swept but packed St Peter's Square erupted with a mix of joy and not a little shock as clouds of white smoke told the crowds - and the rest of the world's 1.2 billion Catholics - that a new pontiff had been chosen on just the second day of voting. But the noise that greeted the billowing smoke was nothing compared to the sound that met Jorge Mario Bergoglio of Buenos Aires when he appeared on the balcony as the 266th successor of St Peter. By 8.10pm local time when the newly elected Pope Francis I emerged in white papal robes to cheers of "Viva il Papa" ("Long live the Pope"), the crowds stretched back from the vast Piazza way to the end of Via della Conciliazione, the 500-metre long road connecting the Vatican to the Tiber. Cheering wildly, some of the faithful were so excited they downed their umbrellas despite the driving rain. Others burst into tears. One weeping nun was mouthing the words "Che meraviglia" ("How wonderful"). It didn't seem right - or necessary - to ask how she felt. The name of the new pontiff had been announced in latin moments earlier by the French cardinal Jean-Louis Tauran after he had declared "Habemus papam" ("We have a Pope"). Ten minutes later Francis I - the first Pope with that name, the first from outside Europe in modern times, and the first Jesuit pontiff - appeared on the balcony looking vaguely stunned. But within a minute or so he composed himself and spoke to the huge crowd. Brothers and sisters, good evening. Thank you for the welcome. He even made a little joke, noting the cardinals had gathered to pick a bishop of Rome "but have chosen one from far away - but here I am." Then he said: "Before everything, I would like to make a prayer for our emeritus bishop Benedict," in reference to his predecessor who quit last month. After Francis's appearance, a brass band made up of the Vatican gendarmerie played in the square below next to helmeted Swiss guards and various divisions of the Italian military, who had earlier exchanged traditional greetings on the steps of the church. After the burst of music Pope Francis I said: "Good night and rest well," before disappearing behind the red curtains. The choice of an Argentine pontiff seemed well received by church insiders. Father Giulio Albanese, director of the Catholic News Agency, said: "He is an extraordinary man. A Jesuit and a person with the ability to make the changes needed in the church. Italian head of state President Giorgio Napolitano said he was "struck by the simplicity" of the new pontiff. Bergoglio adopted the name of Francis, one of the church's most revered saints who was a beggar in 13th century Italy. The name is widely interpreted as sign of humility. Since suffering an infection as a teenager, the 76-year-old has lived with only one functioning lung, although he is said to be in good physical shape. Ahead of the surprise election of the Argentinian cardinal, pundits and Vatican insiders had been heavily tipping two figures: Italy's Angelo Scola, 71 - who would have been the first Italian pope for 35 years - and the Brazilian Odilo Scherer. Yesterday morning support for both was said to be slipping due to reminders of past scandals. Cardinal Scola, the archbishop of Milan, was said by some to be too close to figures embroiled in an emerging health contracts scandal in the northern city. And links to the ultra-conservative Catholic lobbying group Communion and Liberation were not said to be helping his chances. La Repubblica said that Cardinal Scherer, 63, the archbishop of Sao Paolo, might be tainted by his links to the scandal-struck Vatican Bank. With news of the speedy choice of Benedict's successor, some pundits began to read more - retrospectively - into Vatican spokesman Father Federico's comments earlier in the day that election of a new pontiff could be just days or hours away. One leading Vaticanologist, Alberto Melloni, said the white smoke after the final vote of the day had seemed more likely due to the longer-than-usual time it had taken to complete the some of the earlier voting rounds. Although most Vatican watchers had been predicting a result by the end of the week, the election of a pope in just five votes - with the first on Tuesday evening - is not exceptional. The last four popes were all elected within two or three days. Seven ballots have been required on average over the last nine conclaves. Benedict was the clear front runner in 2005 and elected after only four ballots. A history of firsts Francis I is the first pope from the Americas but not the first non-European to hold the position. The first ever pontiff, Peter, was born in the Golan Heights, while there have also been pontiffs from Libya and Turkey. The last non-European was Syrian-born Gregory III, elected in 731. The last pope to take a name that had not already been used was John Paul I. The last Italian pontiff had one of the shortest ever reigns, lasting just 33 days before he died on 26 August 1978. Before him you have to go back more than 1,000 years to find the next first-name pontiff, Lando, who was elected in 913.