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. The Sachs–Wolfe effect induces (10[1])anisotropies (10[1])(“an-eye-SAW-truh-peez”) in this feature from gravitational redshift at the surface of last scattering. A void in the constellation Eridanus is an explanation of a “cold spot” in this feature that was observed by the (10[1])COBE (10[2])(“KO-bee”) and Planck satellites. Arno Penzias and Robert Wilson discovered this feature after making sure it wasn’t interference from bird poop (10[1])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[1]0[2])