Cosmic Microwave Background — 2D Sky Map & Blackbody Spectrum

This 2D simulator walks through cosmic recombination on a canvas equirectangular sky map: drag the cosmic-time slider (or press play) to move from hot opaque plasma glowing at thousands of kelvin, through the moment the universe turns transparent at redshift z≈1100, to today's whole-sky microwave afterglow at T≈2.725 K. Because the real temperature anisotropy is only about one part in 100,000, an exaggeration slider amplifies the pattern up to 100,000× so the ripples become visible, while the live readout always reports the true, un-exaggerated redshift, age and ΔT/T. A second panel plots the live Planck blackbody spectrum for the current temperature, with its peak frequency tracked by Wien's law — the same spectral shape that confirmed the CMB is genuine thermal radiation from the early universe.