A flat Universe from high-resolution maps of the cosmic microwave background radiation

The blackbody radiation left over from the Big Bang has been transformed by the expansion of the Universe into the nearly isotropic 2.73 K cosmic micr owave background. Tiny inhomogeneities in the early Universe left their imp rint on the microwave background in the form of small anisotropies in its t emperature. These anisotropies contain information about basic cosmological parameters, particularly the total energy density and curvature of the Uni verse. Here we report the first images of resolved structure in the microwa ve background anisotropies over a significant part of the sky. Maps at four frequencies clearly distinguish the microwave background from foreground e mission. We compute the angular power spectrum of the microwave background, and rnd a peak at Legendre multipole I-peak = (197 +/- 6), with an amplitu de Delta T-200 = (69 +/- 8) mu K. This is consistent with that expected for cold dark matter models in a flat (euclidean) Universe, as favoured by sta ndard inflationary models.