COPENHAGEN, Denmark (AP) — Queen Margrethe II, Denmark’s monarch for more than half a century, stunned her country when she announced on New Year’s Eve that she will hand over the throne to her eldest son, Crown Prince Frederik.

Her abdication on Sunday will be the first time a Danish monarch has stepped down voluntarily in nearly 900 years.

Here are five things to know about the abdication of Margrethe, currently the longest-reigning monarch in Europe:

WHY IS DENMARK’S QUEEN MARGRETHE ABDICATING?

Other news Who is Crown Prince Frederik, Denmark’s soon-to-be king? Denmark’s queen makes one last public appearance before stepping down in a rare abdication Denmark’s Queen Margrethe II to step down from throne on Jan. 14

Before Margrethe, 83, announced that she would resign, most royal watchers assumed she would live out her days on the throne, as is tradition in Denmark. Margrethe had showed no signs of wanting to retire from her largely ceremonial position. Until recently, she had insisted that she considered being queen a job for life.

Health issues apparently made her reconsider. Margrethe underwent major back surgery last February and didn’t return to work until April. In her speech, she said the surgery prompted “thoughts about the future” and when to pass on the responsibilities of the crown. “I have decided that now is the right time,” she said.

Even the prime minister was unaware of the queen’s intentions until just before the announcement.

WHAT IS THE MONARCH’S ROLE IN DENMARK?

Denmark’s monarchy traces its origins to 10th century Viking king Gorm the Old. The monarch’s powers once were absolute, but today the royal family’s duties are largely ceremonial and defined by the constitution. The monarch is Denmark’s head of state and a symbol of the nation, but political decision-making rests with the Cabinet and Parliament.

Queen Margrethe is highly popular in Denmark, and so is the monarchy. A recent survey showed 70% of Danes favor it.

Margrethe will retain the title of queen after she steps down.

HOW DOES QUEEN MARGRETHE’S ABDICATION HAPPEN?

Even though no Danish monarch has voluntarily relinquished the throne since King Erik III Lam in 1146, the Danish Act of Succession states that the same provisions apply in an abdication as when the sovereign dies.

The queen will formally sign her abdication on Jan. 14 at a state council, a meeting with the Danish Cabinet at the Christiansborg Palace, a vast complex in Copenhagen that houses the Royal Reception Rooms and Royal Stables as well as the Danish Parliament, prime minister’s office and the Supreme Court.

At that meeting, her 55-year-old son will become King Frederik X. His Australian-born wife Mary, 51, will become queen of Denmark and their oldest son, Christian, 18, will take over the title of crown prince. Prime Minister Mette Frederiksen will proclaim the new king to the nation on the balcony of the Christiansborg Palace.

Unlike in the UK, there is no coronation ceremony in Denmark. Copenhagen’s Tivoli Gardens amusement park says it will celebrate the new king and queen with the biggest fireworks show in the park’s 180-year history.

IS MARGRETHE SETTING AN EXAMPLE?

Few royals in European history have given up the throne voluntarily, but things have started to change. In the Netherlands, it’s now the norm for older monarchs to hand over the crown to younger generations: Queen Beatrix abdicated in 2013, following in the footsteps of her mother, Queen Juliana, and grandmother Queen Wilhelmina. Not long after Beatrix, Belgium’s King Albert II and Spain’s King Juan Carlos I retired and were succeeded by their eldest sons.

However, until Margrethe’s announcement, there was no sign their counterparts in Scandinavia would follow suit. Norway’s 86-year-old King Harald V, who has been hospitalized several times in recent months, has not indicated he’s considering abdicating in favor of his son, Crown Prince Haakon. Neither has Sweden’s 77-year-old King Carl XVI Gustaf, who last year celebrated 50 years on the throne.

But Margrethe’s unexpected move suggests anything is possible.

WHAT IS MARGRETHE’S LEGACY?

Queen Margrethe was 31 when she ascended the Danish throne on Jan. 14, 1972, just hours after her father, King Frederik IX, died following complications from a lung infection. The chain-smoking queen quickly endeared herself to Danes with her wit and down-to-earth manners.

She traveled the nation and made frequent visits to the semi-autonomous Danish territories of Greenland and the Faroe Islands. A talented artist, she painted and designed ballet costumes, church vestments and dinnerware. She even made illustrations for a limited edition of J.R.R. Tolkien’s “The Lord of the Rings.”

Listening to the queen’s televised speech on Dec. 31 became part of New Year’s Eve rituals. She often encouraged Danes to treat each other with respect. As Frederiksen put it, the queen put into words “who we are as a people and as a nation.”

Margrethe’s husband, the French-born Prince Henrik, died in 2018. The couple had two children, Frederik and Prince Joachim, and eight grandchildren.

While Margrethe’s reign has been largely free of scandal, she stirred uproar inside the family in 2022 when she stripped Joachim’s four children of their royal titles. Her decision was in line with other European royal houses and in keeping with the times. Joachim said he was saddened. Margrethe later apologized but stood by her decision.