A low-cost passive radiative cooling panel includes an emitter layer disposed under an upper reflective layer, where the emitter layer includes metamaterial nanostructures (e.g., tapered nanopores) configured to dissipate heat in the form of radiant energy that is transmitted through the reflective layer into cold near-space. In an embodiment the emitter layer includes ultra-black material configured to emit, with an emissivity close to unity, radiant energy having wavelengths/frequencies that fall within known atmospheric transparency windows (e.g., 8-13µm or 16-28µm). In a practical embodiment the emitter layer is formed using a modified Anodic Aluminum Oxide (AAO) self-assembly technique followed by electroless plating that forms metal-plated tapered nanopores. The reflective layer includes a distributed Bragg reflector configured to reflect at least 94% of incident solar light while passing the emitted radiant energy, and in some embodiments is implemented using a low-cost, commercially available solar mirror film.