Photograph by CBI/Caltech/NSF
Coming closer and closer to the scene of the big bangthe event that spawned the universe some 14 billion years agoastronomers have detected radio signals (above). Captured by the Cosmic Background Imager telescope in Chile, this high-resolution view of a tiny patch of sky (equal to a few diameters of the moon) records microwave light emissions that have traveled about 14 billion years to reach Earth. Colors reflect the varying intensities of radiation, with red indicating cooler areas and white marking the hot spots. The difference between hot and cool is incredibly minuteas small as ten millionths of a degree. These modest fluctuations were the seeds that later grew into the galaxies and galaxy clusters that we see today.