2) When your experiment yields results that match your hypothesis, you consider that evidence.
3) When you have sufficient evidence, you upgrade your hypothesis to a theorem.
According to the Wikipedia article, we've got at least two probes that are producing results in line with our hypotheses. The bar for wikipedia is "sourced", not proven theorem with scientific rigor. In this case, we're in some nebulous area between 2 and 3. I think that meets the bar for an encyclopedia, which is intended to serve as a summary for these types of things.
Hit the sources and the transitive closure of references for more details.