• Prince William and Kate Middleton attended the inaugural Earthshot Prize ceremony in London Sunday
  • The duke made the surprise announcement that next year's ceremony will be held in the U.S. 
  • Prince Charles expressed support for his son's project and praised Prince William for his commitment to protecting the planet

Prince William and Kate Middleton may visit the U.S. next year.

On Sunday, the Duke and Duchess of Cambridge attended the inaugural Earthshot Prize ceremony in London, where Prince William made the surprise announcement that next year's ceremony will be held in the U.S. 

A Kensington Palace spokesperson told People that further details on the couple's travel plans will be announced in due course.

Prince William and his wife last visited the U.S. in 2014. Their three-day east coast trip included the couple's first visit to New York City and the duke's first trip to Washington, D.C.

The outlet suggested that Middleton may have hinted at a potential visit to America next year with the dress she wore to the Earthshot Prize ceremony. She previously wore the flowy, lilac Alexander McQueen gown on her and Prince William's first visit to the U.S. in 2011.

The duchess styled her hair in curls and accessorized with diamond earrings for Sunday's ceremony. Meanwhile, Prince William looked dapper in a green velvet tuxedo, black pants and black shoes.

The prince's surprise announcement came at the end of the inaugural awards show. "I hope you agree that London and the U.K. has put on quite a show for our first year. So, for the second year, we need to pass the baton to a country whose leadership is essential for all five of our Earthshots," Prince William said.

"Where better than the nation that inspired the Moonshot all those years ago," he added, referring to his inspiration for the prize – President John F. Kennedy's shooting for the moon in the 1960s. "I'm delighted to announce that the Earthshot Prize will be heading to the United States of America in 2022."

Prince William also had a message for "all the young people watching tonight," saying that he plans to dedicate the next 10 years to finding solutions to repair the planet.

"Please keep learning, keep demanding change, and don't give up hope. We will rise to these challenges," he concluded.

According to the Royal Foundation website, the Earthshot Prize will award five winners who "find the most inspiring solutions to the world's greatest challenges" every year between 2021 and 2030. An awards ceremony will take place in different cities across the world within that timeframe, the website said.

Prince Charles expressed his support for his son on social media, praising Prince William for his commitment to protecting the planet.

"I am very proud of my son, William, for his growing commitment to the environment and the bold ambition of the Earthshot Prize. As a world, we need to come together to inspire, reimagine and build the sustainable future we so desperately need," Prince Charles wrote on Twitter

The Duke and Duchess of Cambridge also shared on Twitter a snap of them from the event. Their fans and supporters flooded the post with comments praising and congratulating the couple, especially the duke who started the annual global prize.

"Congratulations William, this is your baby. Optimism and innovation being supported can create real change. I'm glad you set this up to support those who have the ideas to fix this world. Let's celebrate and support them," the fan wrote

Prince William and Kate Middleton LONDONDERRY, NORTHERN IRELAND - SEPTEMBER 29: Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge visit the Ulster University Magee Campus on September 29, 2021 in Londonderry, Northern Ireland. Photo: Chris Jackson/Getty Images