Astronomers have found an enormous empty place in the universe — a hole nearly a billion light-years across with no stars, no galaxies, no gases, and not even never-seen dark matter. The void, considered a “cold spot” in the universe, dwarfs all other similar empty places. They identified the enormous hole by studying data from the Very Large Array radio telescope in New Mexico.

Their work, which has been accepted for publication in the Astrophysical Journal, showed a large and surprising drop in the number of galaxies in a region of the sky in the constellation Eridanus. The area had greatly interested astronomers because it stood out in a map of cosmic microwave background radiation — the faint remaining radiation from the Big Bang. The huge void’s temperature was measured to be ever-so-slightly cooler than surrounding regions.

The reason is that it doesn’t have matter to produce energy when cosmic radiation passes through. “Not only has no one ever found a void this big, but we never even expected to find one this size,” said Lawrence Rudnick of the University of Minnesota.

“What we’ve found is not normal, based on either observational studies or on computer simulations of the large-scale evolution of the universe,” said co-author and colleague Lilya Williams.

They called the discovery especially exciting because irregularities in the cosmic microwave background give information about what the universe was like only a few hundred thousand years after the Big Bang.