OTTAWA -- Self-described space buff King Philippe of Belgium began a weeklong visit to Canada on Monday with his wife, Queen Mathilde, saying he wanted to view the country through the eyes of an astronaut.

He was, of course, referring to his host, former space explorer-turned Gov. Gen. Julie Payette, who greeted the royal couple at Rideau Hall at the start of their whirlwind state visit.

"I love space," King Philippe said to the delight of Belgian flag-waving onlookers as he was formally welcomed to the nation's capital.

"So I'm very happy to see the country and the world through your eyes, the eyes of an astronaut," he said to Payette.

The king and his wife were scheduled to take part in more down-to-earth pursuits over the rest of the five full days of their tour -- the first Belgian state visit to Canada in over 40 years.

Monday's events included the planting of a sugar maple tree in the frozen ground of Rideau Hall, a visit to a sugar bush, the placing of a wreath at the Tomb of the Unknown Soldier at the National War Memorial and meetings on Parliament Hill bringing together delegations from Canada and Belgium.

A meeting planned with Heritage Minister Melanie Joly, to discuss cultural ties between the two countries, was cancelled, however, after Joly's flight to Ottawa was abruptly grounded by computer system disruptions at Air Canada.

And officials narrowly avoided a hitch in the tree-planting ceremony.

"While we were preparing for the tree planting ceremony on the grounds of Rideau Hall, it was brought to our attention that there was a mix up with a small flag that was used to help identify the tree planted by Her Majesty Queen Fabiola in 1977," Marie-Eve Letourneau wrote in an email, adding that the situation was rectified before the current royals arrived.

One of the main thrusts of the state visit is a "thank you" of sorts for Canada's involvement in the liberation of Belgium during the First World War, the king said.

"We owe our freedom to the military men who came to our country 100 years ago to end the First World War," he said as he was greeted by Payette.

"We in Belgium, we don't forget that."

To mark the closing of the centennial commemorations of the First World War in both countries, the royal couple was scheduled to attend a ceremony Tuesday where a cannon from the war was to be loaned to the Canadian War Museum.

With Europe facing down a protectionist administration in Washington -- the latest measure being steel and aluminum tariffs announced last week that Canada has seemingly, temporarily avoided -- the royal visit also provided an opportunity for both Brussels and Ottawa to tout the positive impacts of free and open trade.

"The globalization of (trade) is increasing," Payette noted as she welcomed the couple.

"And with the Comprehensive Economic and Trade Agreement that has been made with Europe, we will increase and progress for the benefit of all countries."

Belgium was a holdout in signing CETA, when one of its regions threatened to effectively veto the agreement, and has given indications recently that it could take a year or more to ratify the pact between Canada and the European Union.

Later Monday, Payette gave the royals a glimpse of the planet through her eyes at a state dinner, where she spoke of the intricate connections that tie Canada, Belgium and the rest of the world together. And she encouraged everyone in the room to think of how people should live in harmony on the only planet they know, telling the gathering that "the world is not small."

The Belgian monarchs are also to visit Toronto and Montreal during their tour, accompanied by a delegation that includes political and business leaders and the rectors of the main Belgian universities.