New observations of the oldest light in the universe have enabled astronomers to determine the age of the cosmos with unprecedented precision, infer the existence of a vast sea of neutrinos, and better gauge the start and duration of the long-ago era when the first stars switched on.
The findings come from an analysis of 5 years of observations of the cosmic microwave background—the radiation left over from the Big Bang—using NASA's Wilkinson Microwave Anisotropy Probe (WMAP).
The glow was generated at the birth of the universe, but WMAP sees the radiation as it appeared when the universe was about 380,000 years old. That's when the cosmos became cool enough for electrons and ions to combine into neutral atoms, releasing the radiation these charged particles had trapped. A snapshot of the early universe, the radiation is riddled with regions slightly hotter or colder than average-markings of the primordial lumps that grew into galaxies and galaxy