The size of this feature’s uniformities is determined by the extent of Silk damping. The BOOMERanG and MAXIMA experiments both imaged this feature with a balloon at an altitude of 40 kilometers. This feature’s polarization is divided into E- and B-modes. (10[2])The Sachs–Wolfe effect induces anisotropies (“an-eye-SAW-truh-peez”) in this feature from gravitational redshift (-5[1])at the surface (10[1]-5[1])of last scattering. A void in the constellation Eridanus is an explanation of a “cold spot” in this feature that was observed by the COBE (“KO-bee”) and Planck satellites. Arno Penzias (10[1])and Robert Wilson discovered this feature after making sure it wasn’t interference from bird poop on their antenna. This feature has a near-perfect blackbody spectrum at about 2.7 kelvins. For 10 points, name this leftover radiation from the Big Bang. ■END■ (10[2]0[1])