We are entering the age of planetary politics defined by consciousness of human impact on the Earth System, and the planetary ecosystem's responses to our activities. This poses a major challenge to democratic theory. How do we protect life without evoking a planetary sovereign? This article argues that the planetary condition requires imaginatively expanding existing democratic concepts to make room for new connections, realities, and beginnings. It demonstrates this by focusing on Hannah Arendt's notion of plurality as the law of the earth. Read through the Roman lex, which emerges from the conflict between the plebs and the patricians, this notion helps us imagine a planetary politics premised on the creation of new relationships between previously discrete entities. Building on this interpretation, I discuss scientific expertise and indigenous perspectives as modes of cultivating political imagination to expand our understanding of the democratic stage beyond the human species.