Earth is a blackbody[1]. We receive heat from the sun in the form of radiation. We also radiate heat out to space.
> Of particular importance, although planets and stars (including the Earth and Sun) are neither in thermal equilibrium with their surroundings nor perfect black bodies, black-body radiation is still a good first approximation for the energy they emit.
Fine, you win Timon3, earth is not a blackbody because blackbodies don't actually exist.
It's fine to say "the earth behaves similarly to a black-body" or "a black-body is a good approximation for the earth". But that's different from "the earth is a black-body".