Game of Thrones star Jason Momoa–whose father is Native Hawaiian–is leading the charge to join the movement against construction of the Thirty-Meter Telescope (TMT) on the summit of Mauna Kea.

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The massive observatory–which is being funded in part by the University of California–would join the 13 existing telescopes on Mauna Kea, the highest point in all of Hawaii.

Led by Native Hawaiian and environmental activists based in Hawaii, the Protect Mauna Kea campaign has received international attention thanks to Momoa, who's recruited both his fictional and real-life spouses, Emilia Clarke and Lisa Bonet, as well his own stepdaughter, Zoë Kravitz.

Other celebs lending their support to the campaign are Jai Courtney, Ian Somerhalder, Nicole Scherzinger and Kelly Slater.

A statement from Kahea: The Hawaiian Environmental Alliance explains why many Native Hawaiians and other island residents see the proposed telescope as injust:

Forty years ago, the people of Hawai‘i agreed to share two of our highest and most sacred summits with a small community of UH astronomers–on the promise of protection and stewardship of fragile alpine habitats, endemic native species, and sacred cultural landscapes.

Today, Haleakalā and Mauna Kea have become the target of increasingly aggressive industrial development proposals from some of the world’s wealthiest nations, corporations, and institutions. The promise to mālama (care for) our sacred summits remain unfulfilled.

The footprint of roads, buildings, parking, and ever-larger telescope complexes has grown each decade, while natural and cultural resources have been irreplaceably lost, desecrated and destroyed. New telescopes, buildings and roads are being proposed, while the U.S. Army has announced a proposal to create “landing zones” for risky high altitude helicopter trainings on Mauna Kea and Mauna Loa.