In 1990, measurements from the COBE satellite showed that the spectrum of the CMB matches a 2.725 K black-body to very high precision; deviations do not exceed 2 parts in 100 000. This showed that earlier claims of spectral deviations were incorrect, and essentially proved that the universe was hot and dense in the past, since no other known mechanism can produce a black-body to such high accuracy. Further observations from COBE in 1992 discovered the very small anisotropies of the CMB on large scales, approximately as predicted from Big Bang models with dark matter. From then on, models of non-standard cosmology without some form of Big Bang became very rare in the mainstream astronomy journals.