In May 2019, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services warned that ''around one million animal and plant species are now threatened with extinction.'' In September 2019, Naomi Klein, an astute writer on environmental change, described the interconnected social and ecological breakdowns on the planet in a new book. Ecological crises noted by these and other scholars speak well to the rise of planetary health as a new scholarship. Loss of biodiversity has manifold negative impacts on health, for example, rise of zoonotic infections and changes in healthy microbiome. But reducing our ecological footprints is not enough. We ought to change mindsets, the narrow science, and technology governance regimes that value nature and other life forms instrumentally by their usefulness to us. I describe three new, broader and critically informed, frames on governance for planetary health. First, I explain why we ought to acknowledge animal sentience, for example, as recognized in Article 13 of the Lisbon Treaty in 2009. I describe how political determinants of health, power, and agency operate at multiple sociological and planetary loci, not only among human beings but also at human and nonhuman animal interfaces. Second, planetary health calls for a shift toward ecological and political determinants beyond a narrow anthropocentric view, while resisting the entrenched dogma of exponential growth with finite planetary natural resources. Third, for critically informed governance of emerging technologies in planetary health (e.g., glycomics, artificial intelligence, health care robots), I refer to a question highlighted recently (Frodeman, 2019): ''When Plato (more exactly, Juvenal) asked who guards the guardians, he was questioning whether any group can be trusted to look past its own interests for the common good.'' Hence, it is time we broaden the question ''Who will guard the guardians?'' beyond the scientific community, to actors in science policy as well. Policy questions cannot be limited to ''which social issues emerge from a new technology?'' but ought to include, ''who should be framing science and technology policy, and why?'' Youth leaders of the global climate movement such as Greta Thunberg and others are now rightly asking these epistemological questions that might contribute toward a new social contract on health for all sentient beings on planet Earth. While ecological changes accelerate and a new space industry is emerging, governance for planetary health will continue to be at the epicenter of systems thinking, responsible innovation and science policy in the 21st century.