I've edited this. The 2 answers i've received so far were confused as to my meaning.
I insist that a black body can only radiate the wavelengths that it receives from it's surroundings because it's in thermal equilibrium.
So who's right?
I think that you guys are trying to answer this question without knowing the definition of a black body. A black body is called "black" because it's indistinguishable from it's surroundings. It's in thermal equilibrium with it's surrounding environment. I don't see how any of you guys can say that real-world objects behave like black bodies since A) black bodies are an idealized state, and B) black bodies can not exist in nature.
Given a black body where T=300K (15C). The other guy claims that the BB will radiate at all wavelengths, while I say that radiation will peak at ~10um. He says that any BB, regardless of temperature will radiate the full spectrum including visible light and x-rays. That is simply ludicrous. What he's saying is that we can get more out of a system than we put into it.
Given all that, if you have the interest to answer then would you please stick to the question and not bring real world objects like the Earth and Sun into it. Neither are black bodies. Please stick to black bodies.