Astronomers have seen the beginning of time, using a space telescope that may have captured the primordial light from the first stars that formed after the Big Bang.
The latest images from Nasa's Spitzer telescope are thought to be the murky light given off by the first objects to form in the universe more than 13 billion years ago.
An infrared camera on the Spitzer took pictures of the constellation Draco and scientists masked out all stars and galaxies to reveal the background glow from the first stars.
Researchers from Nasa's Goddard Space Flight Centre in Greenland, Maryland, compared the observations to the glow of city lights at night from an aircraft; the light is too feeble and too distant to resolve individual features.
"We think we are seeing the collective light from millions of the first objects to form in the universe," said Alexander Kashlinsky, the leader of the Nasa study in the journal Nature. "The objects disappeared aeons ago, yet their light is still travelling across the universe."
Cosmologists estimate that the Big Bang was 13.7 billion years ago. Some 200 million years passed after this act of creation before the first stars began to form from cosmic particles and dust. Scientists believe these stars were likely to have been more than 100 times more massive than the Sun, and would have been hot, bright and relatively short-lived, each surviving a few million years compared to the billions of years of conventional stars.
Theorists predicted that the light from these primordial stars would be "stretched" by the expansion of the universe, so would exist not on the ultraviolet region of the spectrum but in the lower energies of the infrared region.
John Mather, a senior project scientist on the Spitzer telescope, said the aim was to capture all infrared light emanating from a region in the deep Draco constellation and process the data to remove light from more recent objects. "We were left with a picture of part of the sky with no stars or galaxies, but it sill had this infrared glow with giant blobs that we think could be the glow from the very first stars," Dr Mather said.
The images could be the first pictures of so-called "population III" stars that were hypothesised as being formed soon after the Big Bang. Population I and II stars are known to exist.
In the early 1990s, another satellite, the Cosmic Background Explorer (Cobe), found all-pervasive microwave radiation in space thought to be the "echo" of the Big Bang.
Nasa said the latest findings from the Spitzer agree with the Cobe results, which had suggested that an infrared background would be found that could not be attributed to the known stars.