Queen Elizabeth II and her husband, Prince Philip, attend the opening of the new Royal Children's Hospital in Melbourne, Australia, in October 2011. Australia's prime minister on Monday dismissed criticism of his decision to name the Duke of Edinburgh an Australian knight, saying Philip has a long history of service to Australia. (Andrew Brownbill/AP)

Britain's Prince Philip, husband of Queen Elizabeth II, currently has 11 separate honors listed in his full name. He's known as the Duke of Edinburgh, Baron Greenwich and a Knight of the Thistle, to list just a few. On Monday he received another title, with Australian Prime Minister Tony Abbott announcing that Philip would become Knight of the Order of Australia.

Now many Australians are asking a big question: Why did their government make a British prince an Australian knight? To complicate matters further, Abbott announced Philip's new title on Australia Day, a national celebration which commemorates the day British settlers first reached Australia in 1788. "Prince Philip's long life of service and dedication should be honored by Australia," Abbott said.

On social media, many mocked the idea that a British prince would be knighted on a day designed to honor Australia.

Philip's new title brings renewed attention to Australia's colonial history. While Australia has been an independent country for 114 years, it remains a Commonwealth nation, and Queen Elizabeth II is officially the Queen of Australia. The country has a significant republican movement, though a 1999 referendum on ending the link to the British monarchy failed to gain the required majority. Recent polls suggest that about 40 percent of the country supports becoming a republic.

Some Australian royalists have hit back at the criticism of Philip's new title, pointing out that Australia's honors have been given out to foreign nationals before – Nelson Mandela received an Order of Australia in 1999, for example, and Prince Charles has been knighted by Australia. Besides, Prince Philip had visited the country many times and had helped to protect Australian ships while working in the Royal Navy during World War II. "Prince Philip is a great bloke who deserves this knighthood," Scott Coleman, a member of the Australian Monarchist League, argued in the Sydney Morning Herald.

Yet Philip, infamous for his caustic wit, was always likely to be a controversial choice for an Australian knighthood. Well known for his politically incorrect "gaffes," in 2002, he had managed to insult Australia's aboriginal community by asking a successful businessman: "Do you still throw spears at each other?"

The controversy is not just about Philip, however. Tony Abbott is a populist conservative who has riled many Australians since taking office in 2013: Just recently, he threatened to "shirtfront," or chest-bump forcefully, Russian President Vladimir Putin, for example.

It was just last year that Abbott unexpectedly announced a return to dames and knights, last used in 1983, for Australia's honor system. Critics lashed out at the move, arguing that the titles were too closely linked to Britain's empire, and that Abbott – a royalist who once wrote a book called "The Minimal Monarchy and Why It Still Works for Australia" – had ignored the country's significant republican movement with the switch. For a government facing a variety of more pressing political problems, the return to knighthoods seemed like a silly sideshow at best.

"Sure as knight follows dame, Tony Abbott's going to take us back to the good old days," Western Sydney MP Ed Husic told reporters at the time. "I think Tony Abbott wants to play Marty McFly."

For Abbott's critics, his decision to honor Philip seems final proof that he doesn't really care what they think. "Tony Abbott runs Australia with a backdrop of kitsch 1950s nostalgia," Darrin Barnett wrote for the Australian Broadcasting Corporation's Web site on Sunday. "And with the appointment of Prince Philip as Australia's newest knight, it is obvious beyond doubt that the PM has now jumped the shark."

They might be right. Abbott seems to have been unmoved by the criticism of Philip's new title. "I'll leave social media to its own devices. Social media is kind of like electronic graffiti, and I think that in the media, you make a big mistake to pay too much attention to social media," the prime minister said Monday. "You wouldn't report what's sprayed up on the walls of buildings."