When Khal Drogo talks, people listen.

And when Jason Momoa — the part Native Hawaiian actor who played the fierce warlord on “Game of Thrones” — takes a stand for his real-life homeland, his fans and celebrity friends join the cause.

The Honolulu-born actor joined an impassioned group of environmentalists and Native Hawaiian activists on Thursday on Hawaii’s Big Island to protest the construction of a $1.4 billion telescope on at a remote spot atop Mauna Kea volcano.

The telescope, known as the Thirty Meter Telescope, is slated to be one of the world’s largest and most powerful, but the site is considered sacred by Native Hawaiians.

Momoa has flooded his Instagram feed with photos supporting the protesters and is urging his celebrity friends to support the cause by signing a Change.org petition to “immediately halt all TMT-related construction” and “stop all arrests” of “those standing in protection of Mauna Kea.”

So far, hundreds of people have joined the protest on the dormant volcano’s summit and at least 31 people have been arrested.

WE ARE MAUNA KEA The ocean embraces her. The land bows before her. Her reach extends to the heavens. Within her care lies all that is essential for life. WE ARE MAUNA KEA! Please click on the link in my profile to sign the petition and stop the construction of TMT and learn more. #wearemaunakea #protectmaunakea Tat yourself. Send it to the world Aloha jason namakaeha momoa

A photo posted by Jason Momoa (@prideofgypsies) on Apr 6, 2015 at 12:26pm PDT

Singer Nicole Scherzinger (who was also born in Hawaii), actors Ian Somerhalder, Jai Courtney, Jill Wagner, and Momoa’s step-daughter, Zoe Kravitz, have shown their solidarity by writing #WeAreMaunaKea on their bodies and urging their collective 8 million followers to sign the petition.

“This is more than an issue for those living on the Big Island,” Momoa wrote on an Instagram post. “This is [sic] global issue of how we are treating our lands. #WeAreMaunaKea represents all of us humans and are [sic] solidarity towards preserving our natural resources and protecting our native habitats.”

• This story was originally published on HuffPost Hawaii.

Read Civil Beat’s latest reporting on the TMT protests:

Moratorium on Mauna Kea Telescope Construction Extended

Telescope Protesters Prepare for Another Police Showdown

Protesters Ask ‘Voice of the Hawaiian People’ to Stop Mauna Kea Telescope

Hawaii Governor Calls ‘Timeout’ on Mauna Kea Telescope Construction

Mauna Kea Telescope Protesters Arrested

Peter Apo: Mauna Kea Under Siege