As the world’s 1.3 billion Catholics mourn the death of their religious leader the Pope, the Vatican will start the process to find Francis’ successor, known as the papal conclave.

A formal gathering of the College of Cardinals is set to be called within weeks, for the official election to get underway.

As part of the conclave — in which only those aged under 80 are entitled to vote — 138 cardinals will meet in the Sistine Chapel of the Apostolic Palace in Vatican City.

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Of the cardinals, two-thirds were appointed by Francis with Europeans making up fewer than half of those eligible to vote.

The sole Australian cardinal, and the youngest member of the College, is Ukrainian-born Mykola Bychok, 45, and was appointed in December last year by Pope Francis.

The process, steeped in tradition and ceremony, sees the electors sequestered from all outside contact until a new Pope is elected, in order to allow the cardinals to hear the will of God.

A two-third supermajority is required to elect a new pontiff, with ballots held as many as four times a day until the threshold is reached.

On failed attempts, the ballots are bundled up and burned along with a chemical to give off a black smoke out of the chimney above the Sistine Chapel, indicating to the world a pope has not yet been chosen.

When one candidate does receive enough support — 92 votes in the upcoming conclave — the ballots will emit an iconic white smoke out of the chimney.

Frontrunners to take up the throne of St Peter as pontiff include the second most senior cardinal in the Vatican, Secretary of State Pietro Parolin, a conservative who will likely stem the progressive tilt Francis has imposed on the Church in the last decade.

Hungarian Cardinal Peter Erdo, Latin Patriarch of Jerusalem Pierbattista Pizzaballa and Cardinal Luis Antonio “Chito” Tagle from the Phillipines are also in the mix.