Julie Payette takes the reigns as viceregal

Former astronaut Julie Payette took the formal oaths of office Monday as she became the country's 29th Governor General in a traditional ceremony on Parliament Hill.

Chief Justice Beverley McLachlin administered the oaths to the 53-year-old in the Senate chamber under the watchful eyes of hundreds of high-powered Canadian audience members, including Prime Minister Justin Trudeau, his cabinet, Indigenous leaders and other dignitaries.

Payette swore the oaths of allegiance of the Governor General and commander-in-chief of Canada, and of the Keeper of the Great Seal of Canada.

After the oaths, cannons outside the Parliament Building crashed out a 21-gun salute, which could be heard inside.

The audience included justices of the Supreme Court, former governors general, several provincial premiers and Payette's friends and family.

Payette was also formally presented with the ceremonial collars marking her as chancellor of the Order of Canada, the Order of Military Merit and the Order of Merit of the Police Forces, as well as head of the Canadian Heraldic Authority.

While much of the ceremony is dictated by protocol, Payette herself chose the music, which included a rendition of Leonard Cohen's "Hallelujah" sung by Joannie Benoit and Melissa Bedard.

The Juno Award-winning Tafelmusik Baroque Orchestra and Choir, of which Payette was a member, also performed.

Trudeau spoke of Payette's flights into space as inspiring moments, calling her a two-time extraterrestrial Canadian.

He praised her as a mother, an athlete, a pilot, a scientist and someone who "went where very few others had dared to go."

"Your journey through space and through life may be unique, but the qualities which underpin every one of your successes are not," he said.

The prime minister also took time to thank Payette's predecessor, David Johnston.

"You have made Canada a stronger and a better country."

One of the first things Payette plans to do as the Queen's representative in Canada is to open an Instagram account. Johnston, her predecessor, never had one, but officials from Heritage Canada say Payette will add to the Governor General's social media arsenal.

She will also take over her predecessor's official Facebook and Twitter accounts.

Payette's embrace of social media appears to be in step with Buckingham Palace, which posted a job advertisement for a social media manager earlier this year as the number of people following the Queen on Twitter was heading toward the three million mark. It has since surpassed that.

Payette, a Montreal-born astronaut, engineer and businesswoman, was accompanied by her 14-year-old son, Laurier Payette Flynn. Her parents and sister and brother were among the invited guests who felt the rumble of a 21-gun salute after Payette signed the oath book and took her seat on the Senate throne.

Following the ceremony, Payette, her son and other dignitaries were scheduled to visit the National War Memorial where the new Governor General would lay flowers on the Tomb of the Unknown Soldier.

Payette had her first audience with the Queen less than two weeks ago, at Balmoral Castle in Scotland, where she received several honours, including the Extraordinary Companion of the Order of Canada.

In his parting statement, issued Friday, Johnston thanked Canadians for the privilege of serving them.

"It has been a great honour to serve as Canada's 28th Governor General, to represent Her Majesty The Queen in this important role within our constitutional monarchy and to give back to this country I love so much," the former academic said.