For Hannah Arendt, authority is the shape educational responsibility assumes. In our time, authority in Arendt's sense is under pressure. The figure of Greta Thunberg shows the failure of adult generations, taken collectively, to take responsibility for the world and present and future generations of newcomers. However, in reflecting on Arendt's use of authority, we argue that her account of authority also requires amendments. Arendt's situating of educational authority in-between past and future adequately captures its temporal dimension. We make explicit another, spatial, dimension: authority in-between world and earth. Arendt's neglect of the material earth also has implications for the relational dimension of authority. Arendt's authority depends on a dichotomy between the private (education, the child) and the public sphere (politics, the adult). This is problematic. First, we agree with Arendt's feminist critics that the personal can be made into the site of the political. Second, we point once more to Thunberg, the child, taking the public stage, thereby contesting the division between public and private. In response, we situate the relational dimension of authority in-between private and public. The three dimensions of educational authority taken together imply that it is situated in-between domains that cannot be reduced to each other or taken as absolutes: past and future (time), world and earth (space), and the private and public sphere (relation). This brings us to our concept of ambiguous authority, which expresses the Arendtian nature of our reflections and the ways in which we seek to renew her original insights on educational authority.