Hundreds of thousands of religious pilgrims and world leaders are arriving in St Peter's Square to witness the ceremonial inauguration of the Pope Francis.
Argentine Jorge Mario Bergoglio became Latin America's first pontiff last week when he replaced 85-year-old Pope Benedict XVI.
It's a day of heavy symbolism and ceremony.
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As part of the official mass, the newly elected Pope Francis will tour St Peter's Square for a few minutes before 9am (7pm AEDT), before praying at the Saint's tomb, and receiving the pallium cloak and the Fisherman's Ring – symbolising St Peter, a fisherman by trade.
A group of more than 100 cardinals will pay homage to Pope Francis – although Pope Benedict XVI had a mixed group of lay people and clergy instead. Pope Francis will then give a homily to the crowd.
Professor Andrew McGowan, Professor of Historical Theology at Trinity University, spoke to SBS about some of the meanings behind the day.
What does the ceremony mean?
"This is the heart of the ceremonial process of Pope Francis' ascension to the role but effectively it took place as soon as he was elected."
"Even this ceremony isn't the end of his inaugural process, because while St Peter's Basilica is the great Church of Rome, it's not actually the cathedral of the bishop of Rome – that's St John Lateran. So at some point after this ceremony the Pope will go to be recognised and installed in his own cathedra – the chair that makes St John Lateran his actual cathedral, and that will perhaps be the end of the beginning for Pope Francis.
I suppose the difference between these things is like the difference between President Obama's election and inauguration. There's actually a process of a legal and electoral character that makes the person an incumbent in the office but it's still helpful for a broader public to have ceremonies that attaches to these processes so people can make public declarations to fulfil the role conscientiously and well."
How has the inauguration ceremony changed in recent history?
"The ceremony for the installation of the Pope has fairly modern form now. It was changed considerably in 1978 when Pope John Paul I was elected Pope.
Prior to him the Popes had actually been crowned with the papal tiara – a rather spectacular sort of object. Really more of an egg-shape crown that the Pope used to wear as a symbol of their office.
The last pope to be crowned in this way was Pope Paul VI. John Paul I - who I think had something in common with Pope Francis - wanted to make the ceremony a much simpler one and to come away from the notion of the papacy as a kind of monarchy, as it reflected the trappings of royalty and so forth.
Since then both of his successors – Pope John Paul II and Pope Benedict the XVI – have had simpler forms of the installation ceremony involving a mass that takes place in St Peter's Square and the placement on the Pope of particular vestments - including what's called the pallium, which is a strip of wool marked with crosses which is a symbol of the pope's office.
Everything we know about Pope Francis himself indicates that we will probably want to emphasise the simpler parts of the ceremony and to emphasise his role as a pastor and a bishop rather than to emphasise his role as a pope and a monarch.
This inauguration is predicted to be a full hour shorter than that of Pope Benedict XVI. What sort of changes to the ceremony will make room for this?
Well I think we'll all be waiting to see exactly what that means. There's an element of suspense in how he'll handle that act of homage. Mainly there are other logistical elements to this that we can't predict.
Pope Francis has already surprised many with his emphasis on simplicity, his obvious seriousness in sending a message to the wider Catholic community and to the world about the core values of the Christian gospel and I imagine that we may see some other aspects of the pomp and circumstance reduced further in an effort to display what he regards as the core message of the Christian church and his own ministry. "
There are some controversial world leaders attending – or refusing to. China has refused to send delegates because of the attendance of Taiwan representatives. Zimbabwe President Robert Mugabe is circumventing an EU travel ban to attend.
"Many heads of government and heads of state have been invited and many will send ambassadors.
Robert Mugabe is probably trying to scratch around for any credibility he can find and the Roman Catholic Church hasn't seen fit to exclude him as he is a head of state.
As far as China and Taiwan are concerned, Vatican City is relatively unusual these days in terms of diplomatic relationships with the Republic of China or Taiwan, and not with the People's Republic. SO it's almost a throwback to a situation other countries were in in the early 1970s. SO those two stories have their own history attached to them."
Then there is the attendance of the Ecumenical Patriarch Bartholomew of Istanbul – the first attendance of an Orthodox Christian leader since 1054.
"As far the Ecumenical Patriarch is concerned, this is really a significant historically, and the fact that he's been invited is significant. The fact that he's willing to come is also significant.
The Eastern Orthodox Church – Russian and Greek groups are perhaps the best known – have viewed the Roman Catholic Church with a mixture of sympathy, hostility and suspicion, one would have to say.
And there are aspects of events in the last 20 or 30 years where relationships actually deteriorated after a bit of a thaw in the 1960s.
Pope John Paul II seemed to support missions by Roman Catholic clergy in areas that were traditionally regarded as orthodox and there have been some particular controversies involving the relationships between catholic and orthodox churches which live side by side in Ukraine for instance.
The fact that the Patriarch is willing to come expresses a strong openness on his part to the possibility of improved relationships with the Vatican.
It will be a sign of a stronger connection than has existed for a thousand years between these two groups but it won't be immediately an end to the disunity between them."
