THE BIG PICTURE
One of the most significant observations of the twentieth century was made in the early 1990s by the Cosmic Back-ground Explorer. COBE measured the feeble back-ground glow thought to be remnant radiation from the Big Bang—the explosion that created the universe.
In 1992, careful analysis of COBE data revealed slight temperature fluctuations in the background glow, which were interpreted as tiny variations in the smoothness of the universe 300,000 years after the Big Bang. These variations had been predicted by the Big Bang theory. Further study may reveal how these irregularities in the distribution of matter resulted in the formation of the galaxies.