Prince William Ends Earthshot Prize Ceremony with a Powerful Speech — and Some Help from Tom Cruise!

Prince William welcomed some Brazilian teens to join him to conclude his speech that wrapped up the Earthshot Prize — and also got a surprise assist from Tom Cruise.

In a surprise moment, the Mission: Impossible star appeared at the fifth Earthshot Prize awards that took place in Rio De Janeiro, Brazil, on Nov. 5 via video message. In it, Cruise praised those gathered for “reminding us what’s possible when commitment meets purpose.”

“Thank you all for all the work you do,” he added. “Congratulations. Enjoy your evening.”

The star-studded evening included performances from Shawn Mendes and Kylie Minogue, and Prince William gave a powerful speech — with help from four young environmental champions.

The Prince of Wales opened with a Portuguese greeting — “Boanoite e bem-vindos!” — before praising the shortlisted finalists for the ideas that add hope for finding solutions to the planet’s pressing environmental problems, adding they were the “world’s true action heroes.”

“When we founded the Earthshot Prize in 2020, we had a 10-year goal, to make this the decade in which we transformed our world for the better,” he said. “We set out to tackle environmental issues head on…and make real, lasting changes that would protect life on Earth.”

“It was a mission driven by the kind of extraordinary optimism we’ve felt here tonight, from these innovators. Their work is the proof we need that progress is possible,” he continued.

He recognized, too, that it is hard to stay positive in such “uncertain times,” but he urged that people should not be discouraged.

“The optimism I felt in 2020 remains ardent today,” William said. 

Then, with the future belonging to young people in his words, he was joined by four teens — Hevellin dos Santos, 15, Julia Ferreira, 15, Miguel dos Santos, 12, and Vicente Fontoura, 14 — who recited, in Portuguese, their visions: for a world powered by “clean energy, where the climate is stable,” in which “clean air and oceans are bursting with life,” a world where “nothing is wasted and forest stretch endlessly,” before a vow to play a part to spread “hope and optimism everywhere.”

He was speaking after the latest cohort of winners of his Earthshot Prize, given in five different categories, had been handed their $1.3 million awards.

Former New Zealand Prime Minister Jacinda Ardern, who serves as a trustee on the board of the Earthshot Prize, tells PEOPLE that Prince William is constantly trying to help the prize winners and finalists expand their ideas five years into the project.

“It’s been, ‘How do we do more? How do we scale? How do we better support the finalists?’ That mission hasn’t changed — just the urgency of why it exists has,” she says.

Mayor of Rio Eduardo Paes, who has spent much of the last few days with William, tells PEOPLE, “He’s an amazing guy. It’s been very nice to see. He took everyone’s heart in Rio, and we’re very proud to have him here. I told him he could have Earthshot Prize every year in Rio, it would be amazing. We are very proud to host him here.”

He adds, “It is such an important discussion in a moment when Brazil is playing an important role in this issue.”

Can’t get enough of PEOPLE’s Royals coverage? Sign up for our free Royals newsletter to get the latest updates on Kate Middleton, Meghan Markle and more! 

Prince William’s last day began by taking the finalists to see the Christ the Redeemer statue and talk about their hopes for their individual projects.

It came after a few days in which he played volleyball to help promote a social enterprise run by a Brazilian Olympian, played soccer with kids who are learning the importance of the environment and climate change message via the sport and spent an afternoon seeing how Indigenous people are working to restore crucial mangroves, a link between the forests on land and the sea.